Atomic Scale Study on Growth and Heteroepitaxy of ZnO Monolayer on GrapheneClick to copy article linkArticle link copied!
- Hyo-Ki Hong
- Junhyeon Jo
- Daeyeon Hwang
- Jongyeong Lee
- Na Yeon Kim
- Seungwoo Son
- Jung Hwa Kim
- Mi-Jin Jin
- Young Chul Jun
- Rolf Erni
- Sang Kyu Kwak
- Jung-Woo Yoo
- Zonghoon Lee
Abstract
Atomically thin semiconducting oxide on graphene carries a unique combination of wide band gap, high charge carrier mobility, and optical transparency, which can be widely applied for optoelectronics. However, study on the epitaxial formation and properties of oxide monolayer on graphene remains unexplored due to hydrophobic graphene surface and limits of conventional bulk deposition technique. Here, we report atomic scale study of heteroepitaxial growth and relationship of a single-atom-thick ZnO layer on graphene using atomic layer deposition. We demonstrate atom-by-atom growth of zinc and oxygen at the preferential zigzag edge of a ZnO monolayer on graphene through in situ observation. We experimentally determine that the thinnest ZnO monolayer has a wide band gap (up to 4.0 eV), due to quantum confinement and graphene-like structure, and high optical transparency. This study can lead to a new class of atomically thin two-dimensional heterostructures of semiconducting oxides formed by highly controlled epitaxial growth.
Heteroepitaxy of metal oxide semiconductors on two-dimensional (2D) layered nanomaterials, combining wide band gap and high charge carrier mobility, has become a new integration method for fabricating flexible (1-3) electronic and optoelectronic devices.
Among semiconductor oxides, zinc oxide (ZnO) has been used in novel transparent electronic devices (4-7) as forms of epitaxial layer on graphene. Thermodynamically, hexagonal wurtzite ZnO (5) is the most stable and common form. The wurtzite structure of ZnO can be transformed to a planar (8-10) ZnO monolayer in which Zn and O atoms reside in a trigonal planar coordination, instead of the bulk tetrahedral configuration formed when ZnO is thinned down to a few atomic layers. Since ZnO monolayers on graphene can have many applications in switching electronics and photoactive devices, growth of thin ZnO layers on graphene has been studied extensively. (11-13)
Various deposition techniques, including metal–organic vapor phase epitaxy, (14) as well as hydrothermal (15, 16) and electrochemical deposition, (17-19) have been employed for the heteroepitaxial growth of ZnO semiconductors on graphene. However, the strongly hydrophobic graphene limits metal oxide deposition and the wide application of this attractive combination.
Here, we provide experimental evidence for the epitaxial growth of a ZnO monolayer on graphene using atomic resolution transmission electron microscopy (ARTEM) along with the corresponding image simulations and first-principles calculations. Furthermore, we demonstrate through in situ observation the atom-by-atom growth of zinc and oxygen at the zigzag edge of the ZnO monolayer on graphene at the atomic scale. We also confirm the heteroepitaxial growth and misorientation angles of this ZnO monolayer by direct observation and energy calculations of the heterostructures. In addition, we demonstrate the presence of 2–3 nm quantum dots (QDs) of the epitaxial ZnO monolayer grown by atomic layer deposition (ALD). Unlike conventional bulk ZnO, ZnO QDs have potential applications in nanoscale devices, such as photonic and electronic devices, due to the quantum confinement effect. (20, 21) The structural and optical properties of the ZnO monolayer on graphene are studied to exploit the quantum phenomena arising from confinement in QDs.
In particular, a ZnO monolayer can preserve the graphene’s intrinsic electronic properties, (22-24) high carrier mobility, (25) and optical transmission. (26) Ultrathin 2D oxide semiconductors on graphene have potential applications in optoelectronic devices, and a new class of 2D heterostructures may arise through this deposition route.
Graphene is a strongly hydrophobic material, which limits the epitaxial growth of semiconductor oxides and thus hinders their various optoelectronic applications. Previously, we attempted to tailor the surface property of graphene surface from hydrophobic to hydrophilic using several methods including O2 plasma, (27, 28) O3 treatment, (29, 30) UV irradiation, (31, 32) surface chemical doping, (33) and electrical field. (34)
In this study, we select the UV/ozone treatment (35-37) because it provides sufficient energy to reform the graphene surface state but does not damage the graphene, and it is a simple method uniformly applicable to large areas.
Figure 1 shows a ZnO monolayer grown on pristine graphene and the UV/ozone-treated graphene after 20 ALD cycles. Figure 1a shows the ZnO deposited on the pristine graphene surface after 20 ALD cycles. Blue indicates the crystallized ZnO monolayer. The inset in Figure 1a shows mostly spot patterns of graphene because there is little crystallized ZnO. Figure 1b, however, shows the larger size of ZnO crystals epitaxially grown on the UV/ozone-treated hydrophilic graphene surface after 20 ALD cycles. The diffraction pattern shown in the inset of Figure 1b displays the mixed spot patterns of crystalline ZnO and graphene. The crystalline ZnO monolayer is clearly visible and the ZnO coverage is much larger on the UV/ozone-treated graphene. The misorientation angle of 0° is the most common. In order to investigate the effect of UV/ozone treatment on graphene, Raman spectra are obtained for the graphene as a function of the UV/ozone treatment time from 0 to 600 s (Figure 1c). After up to 180 s of UV/ozone treatment, pristine graphene bands remain intact. However, after 300 s of the treatment, strong D (1345 cm–1) and D′ (1618 cm–1) bands are observed in the spectra, suggesting the formation of lattice defects. These results indicate that excessive UV/ozone treatment damages the graphene lattice. (35) The X-ray photoelectron spectroscopy (XPS) results (Figure 1d) mainly display a C 1s peak, related to the sp2 C–C bonds based on the UV/ozone treatment time. The XPS spectra show a gradual decrease in the height and broadening of the sp2 C–C bonds with increasing UV/ozone treatment time. Such behavior is likely caused by p-type doping induced by the UV/ozone treatment. (35) The results of Raman spectroscopy and XPS indicate that excessive UV/ozone treatment induces significant crystal lattice damages and graphene doping. The effects of UV/ozone treatment on the electrical properties are also investigated through field-effect transistor (FET) measurements. The FET devices are fabricated to have a graphene channel (width = 200 μm, length = 5 μm) between the Au electrodes on the SiO2/Si substrate. The mobility of the three pristine graphene FETs is 1346, 1648, and 1490 cm2/V·s, which changes to 1281, 1424, and 1361 cm2/V·s, respectively, after the UV/ozone treatment without remarkable Dirac voltage changes. Thus, the mobility decreases only by about 10%, suggesting that our UV/ozone treatment does not severely deteriorate the graphene structure (Figure 1e,f). The inset in Figure 1e shows the change in the contact angle of water on graphene after the 180s UV/ozone treatment, which is measured with an optical contact angle meter in ambient environment. The contact angle decreases from 87° to 67° for the UV/ozone-treated graphene, indicating enhanced hydrophilicity. Therefore, we find that 180 s is the optimum UV/ozone treatment time for ZnO deposition on a graphene substrate. Under these conditions, the graphene surface shows hydrophilicity without deteriorated electrical properties caused by lattice damage.
Figure 1
Figure 1. ZnO monolayer on pristine and UV/ozone-treated graphene. (a) Atomic resolution image of ZnO nanoclusters on pristine graphene. The inset in the upper right corner shows the Fourier transform of the image. (b) Atomic resolution image of ZnO nucleation on a graphene substrate after 180 s of UV/ozone treatment. The inset in the upper right corner shows the Fourier transform of the image. (c) Raman spectra of UV/ozone-treated graphene after different treatment times. (d) XPS spectra of the UV/ozone-treated graphene after different treatment times. (e) Current–gate voltage curves of the graphene for different UV/ozone treatment times. The inset in the upper corner shows the contact angle to the graphene substrate treated to UV/ozone from 0 to 180 s. (f) Mobility-carrier concentration curves of the graphene for varying UV/ozone treatment time. The scale bar is 2 nm.
The diffusion of monomers is the basic form of mass transport on graphene flat surface. (38, 39) For technological purposes, it is often desirable to achieve layer-by-layer or Frank–van der Merwe growth to produce smooth layers. Under thermodynamic equilibrium conditions, the growth mode is determined by the surface energy. (40) The epitaxial growth of ZnO wets the flat graphene surface completely when the surface energy of the ZnO monolayer is lower than that of the graphene surface; in the opposite case, the deposited material forms three-dimensional islands, following the Vollmer–Weber growth mode. (40)Figure 2 shows time-elapsed ARTEM images taken during the epitaxial growth of the ZnO monolayer on the graphene surface triggered by electron beam irradiation. First, the ZnO monomer is adsorbed onto the graphene’s flat surface (Figure 2a). Then, the diffused and desorbed species may also attach to an island nucleated in an earlier growth stage (Figure 2b). The next step is the formation of clusters, where unstable clusters are desorbed (Figure 2c). Then, the ZnO cluster develops which exhibits a periodic atomic arrangement. The epitaxially grown ZnO crystals have a diameter of 2 nm (Figure 2d). Especially, in the lateral growth of ZnO, the highest growth rate is observed along the c-axis and the large facets are usually {101̅0} and {112̅0}, because it is energetically favorable when the [101̅0] or [112̅0] direction of ZnO matches the [101̅0] direction of graphene. (41) The ZnO monolayer has a (0001) polar surface plane, which is atomically flat and stable. (42, 43) During the coalescence stage (Supporting Figure 1), there is a distinct difference in the relative orientation of the ZnO crystals and the graphene surface. The ZnO monolayer has a facet edge development as shown in the time-elapsed images. In addition, it has a graphene-like structure along the c-axis and the ZnO adatoms are adsorbed onto the {101̅0} facets. This shows that some crystals in the ZnO monolayer undergo nonepitaxial growth, rotated by 10° during the initial growth stage (Supporting Figure 2).
Figure 2
Figure 2. Time-elapsed ARTEM images showing ZnO monolayer growth behavior under electron beam irradiation. (a) ZnO monomer is adsorbed onto the graphene substrate. (b) ZnO becomes amorphous. (c) ZnO forms clusters; unstable clusters are desorbed. (d) The ZnO cluster has periodic atomic arrangement for epitaxial growth on graphene. The scale bar is 1 nm.
ZnO is crystallographically misoriented by 30° with respect to the graphene substrate to minimize the dangling bond density. The misorientation angles of 0° and 30° can be explained by the heteroepitaxial relationship between the ZnO monolayer and graphene; it is energetically favorable when the [101̅0] or the [112̅0] crystallographic direction of ZnO matches the [101̅0] direction of the graphene. (41)Figure 3 shows the heteroepitaxial relationship of the ZnO monolayer with the graphene surface, as revealed through ARTEM analysis. Figure 3a shows an atomic resolution image of the ZnO monolayer misoriented by 30° on the graphene. The inset in the upper right corner shows the Fourier transform of the image. According to the ARTEM analysis, the atomic model of ZnO/graphene rotated by 30° is simulated as shown in the Supporting Figure 3a. The corresponding simulated diffractogram (Supporting Figure 3a) is in good agreement with the diffractogram of the ARTEM image (Figure 3a). The ZnO monolayer, misoriented by 0° and 30° on the graphene, appears during the initial growth stage and eventually becomes misoriented by 0° as ZnO crystals grow further.
Figure 3
Figure 3. Heteroepitaxial relationship of the ZnO monolayer on graphene analyzed through aberration-corrected TEM. (a) Atomic resolution image of ZnO misoriented by 30° on graphene. The inset in the upper right corner shows the Fourier transform of the image. (b) Atomic resolution image of ZnO misoriented by 0°. The inset in the upper right corner shows the Fourier transform of the image. Triangular moiré patterns are repeatedly observed every 2 nm. (c) Histogram of misorientation angles of ZnO on graphene and adhesion energy of oxygen-terminated triangular ZnO nanocluster on graphene surface vs the misorientation angle. (d) Raw image of part a. (e) Image simulation result of the ZnO monolayer on graphene. (f) Normalized intensity profiles acquired from the image simulation (black line) and experimental image (red line), corresponding to marked profiles in red dashed lines in parts d and e. The scale bars indicate 1 nm.
Figure 3b shows an ARTEM image of the ZnO layer on graphene misoriented by 0°. The image clearly shows a unit triangular Moiré pattern with a periodicity of about 2.0 nm, which is attributed to the lattice misfits. The determined lattice constants for ZnO (a ≈ 3.3 Å, c ≈ 5.2 Å) and graphene (a ≈ 2.46 Å) agree well (10, 11) with the reported lattice constants of graphene-like ZnO and graphene. These results are in good agreement with the atomic model and the diffractogram (Supporting Figure 3c,d, respectively). In order to reveal the specific misorientation angles observed through the experiment, the stability of each misorientation angle is assessed by calculating the adhesion energy (Ead) as follows:(1)where Etotal, EZnO, and EG represent the energies of the ZnO nanocluster on graphene, the freestanding ZnO nanocluster, and the freestanding graphene, respectively, and N is the total number of Zn and O atoms in the ZnO nanoclusters. Based on the density functional theory (DFT) calculations (see DFT calculation in Supporting Information, Note 2) of the different edges of ZnO nanoclusters (Supporting Figure 4 and Model Systems in the Supporting Infomation), the misorientation angles 0° and 30° are more stable for the ZnO monolayer on graphene due to the strong van der Waals interactions between the edge atoms of ZnO and graphene. Figure 3c shows the histogram of the observed misorientation angles and the calculated adhesion energies between the oxygen-terminated triangular ZnO nanocluster and graphene. The counts of the experimental misorientation angle correspond well with the computational adhesion energy.
Figure 3d shows the raw ARTEM image of Figure 3a, and Figure 3e shows the image simulation result of the ZnO monolayer on graphene. It is noteworthy that both images have tiny bright spots in the vacuum regions of the ZnO lattice. The contrast comes from constructive interferences of the exit waves generated by the distance between the ZnO monolayer and the graphene surface. We also compare the variations in the normalized intensity profiles of the experimental image and the simulated image at the imaging condition of the microscope. The similarity of the two intensity profiles in Figure 3d,e confirms the identical atomic structures of ZnO monolayers in these images.
The ZnO monolayer on graphene monolayer assumes a graphene-like structure (8-13) rather than a wurtzite structure. ZnO monolayer nanoclusters have a predominantly zigzag edge configuration with a misorientation angle of 0° on graphene. Here, the in situ observation allows for demonstrating the atom-by-atom lateral growth of zinc and oxygen at a zigzag edge of the ZnO monolayer on graphene at atomic scale, as shown in the Supporting Movie 1. Figure 4a, which is a series of snapshots obtained from the movie, shows time-elapsed images of adsorbed ZnO adatoms on a graphene substrate. In order to understand the lateral growth at the edge, the formation energy, which may reveal the growth path, is estimated through DFT calculation. The formation energy Ef is defined as follows:(2)where Etotal and EG represent the energies of the ZnO monolayer on graphene and the freestanding graphene; EZn and EO are the energies of zinc and oxygen atoms in vacuum; and NZn and NO are the numbers of zinc and oxygen atoms in the total system, respectively. Based on the lateral growth model systems (Supporting Figure 5), the relative formation energy of the ZnO monolayer on graphene is estimated as shown in Figure 4b. After the first unstable adatom absorption, the formation energies tend to decrease. For oxygen- and zinc-terminated zigzag edges, the formation energies gradually decrease as the growth step increases. In particular, a large formation energy drop occurs by stabilizing the ZnO edge when a hexagonal structure is formed by adatom absorption. For the armchair edge, the formation energy fluctuates with increasing growth step. When adatoms form a full hexagonal structure, the formation energy decreases, but when they become dangling atoms, the formation energy increases. Consequently, the lateral growth of ZnO is energetically favorable for the zigzag edge over the armchair edge. In addition, parallel growth is favored less than lateral growth because of the continuous unstable adatom absorption at the pristine edge (Supporting Figure 6).
Figure 4
Figure 4. Lateral growth of the ZnO monolayer along the zigzag edges. (a) Time-elapsed ARTEM images show the adsorbed ZnO adatoms on graphene. Additional details can be seen in Movie S1. (b) Relative formation energy (i.e., ΔEf = Ef_growth step – Ef_initial) of the lateral growth of the ZnO monolayer with oxygen- and zinc-terminated zigzag edges and armchair edge. The red and blue spheres represent oxygen and zinc atoms, respectively, and the gray-stick honeycomb network represents graphene. (c) Raw image of part a at final step 7. (d) Intensity profile acquired from the experimental image (red line). (e) Image simulation of part a at final step 7. (f) Intensity profile acquired from the image simulation (blue line). The scale bar is 1 nm.
Parts c and e of Figure 4 show the raw ARTEM image of Figure 4a at the final step 7 and the corresponding simulation image at the imaging condition, respectively. The ZnO adatoms are adsorbed onto the oxygen-terminated zigzag edges because these edges are more stable than Zn metal edges (Figure 4b). Figure 4d shows an intensity profile in the raw ARTEM image of Figure 4c, where Zn, O, and C atoms can be distinguished, because the Zn atoms display 4.5% higher intensity than the O atoms with ±1.5% deviation in the real image. (44) This result reveals the lateral growth of ZnO as heteroepitaxy growth on graphene at the atomic scale. The observed ZnO monolayer appears crystallographically identical to the graphene-like structure. We draw attention to two findings from the results: First, the ZnO adatoms at the zigzag edges are energetically favorable, and oxygen-terminated edges are more stable than Zn-terminated edges (Figure 4 and Supporting Figure 5). Second, the ZnO adatoms along the growth direction are energetically more stable than those parallel to the growth direction (Supporting Figure 6).
Bulk ZnO has a band gap of 3.37 eV at room temperature. (7) However, ZnO monolayer nanoclusters with a diameter of 2–4 nm or smaller (Figure 5f,g) have increased band gaps due to strong quantum confinement effects (20, 21) and graphene-like crystallographic structure. Therefore, we anticipate a similar drastic change in the band gap of ZnO monolayer nanoclusters.
Figure 5
Figure 5. Electronic and optical properties of ZnO deposited with different ALD cycles on UV/ozone treated graphene. (a) STEM-EELS spectra of ZnO deposited with different ALD cycles on UV/ozone-treated graphene. The extrapolation lines (dashed lines) indicate the band gap (Eg) values 4.0, 3.71, and 3.25 eV. Each curve is scaled differently. (b) Optical transmittance measurement of ZnO deposited with different ALD cycles on graphene. (c–e) Bright-field images of suspended UV/ozone-treated graphene after 10, 20, and 200 cycles of ZnO ALD growth. The scale bar is 200 nm. (f–h) ARTEM images of 10, 20, and 200 cycles of ZnO ALD growth on the UV/ozone-treated graphene substrate. The insets in the upper right corner show the electron diffraction patterns of the imaging regions (f–h). The scale bar is 1 nm.
In this study, we experimentally measure the band gaps of the ZnO nanoclusters and verify the change in the band gaps of the ZnO monolayer QDs grown on graphene.
Figure 5a shows band gap measurements with electron energy loss spectroscopy (EELS) in the scanning transmission electron microscopy (STEM) mode for ZnO grown on graphene with different ALD cycles. Figure 5a shows the obtained EELS spectra after subtracting zero loss peaks. The band gaps are estimated from these spectra using a power law. (45) The results display higher band gap energy for smaller ZnO nanoclusters. For instance, a ZnO sample grown with 10 ALD cycles displays a band gap of 4.0 eV, whereas a ZnO sample grown with 200 ALD cycles exhibits a band gap of 3.25 eV, which is close to the bulk ZnO value. The observed gradual spectral shift in the band edge with the ALD cycles can be attributed to the expected quantum confinement effect. (20, 21)
We also measure the variation in the band gap energy with a different experimental method. Supporting Figure 8 shows the optical transmission spectra obtained from the UV–vis–NIR spectrophotometer. These spectra can provide plots of (αhv)2 as a function of photon energy (hv) for different ALD cycles—where α is the absorption coefficient of ZnO, defined as follows: (46)(3)
Here, Δd (= d2 – d1) is the thickness difference between the two ZnO films, and T1 and T2 are the transmittances of the two films. If d1 = 0 (and T1 = 1), we can also obtain the absorption coefficient of the ZnO film. The linear fit to the rapidly rising part of a spectrum gives the value for the optical band gap. Similar methods have been used for determining band gaps of various composite films. The ZnO band gaps for 10, 20, and 200 ALD cycles are determined in this way (Supporting Figure 8a–c). Indeed, the obtained band gaps are very close to those measured from the STEM-EELS spectra in Figure 5. This again verifies a significant change in band gap due to the quantum confinement effect in ZnO monolayer nanoclusters on graphene. The ZnO monolayer QDs on 2D materials with their tunable band gap can be a promising template for various photonic and electronic device applications. Figure 5b shows optical transmittance data of ZnO deposited with different ALD cycles on graphene. The ZnO films grown on graphene with 10 and 20 ALD cycles are nearly transparent, with flat optical transmittances of T = 97.1% and 96.8% at 550 nm, respectively. However, ZnO films grown with 200 cycles exhibit substantial reduction in transmittance (T = 87.7% at 550 nm). The drop in optical transmittance is highly nonlinear to the number of ALD cycles (47) because the formation of ZnO nanoclusters, as observed in TEM images, results in a nonlinear expansion of the ZnO deposition area with increasing number of ALD cycles. The morphological development of the ZnO nanoclusters and their epitaxial relationship to graphene are characterized using bright-field TEM and atomic-resolution TEM. Parts c–e of Figure 5 show bright-field TEM images of the ZnO nanostructures grown on graphene after UV/ozone treatment for 180 s with 10, 20, and 200 ALD cycles. These TEM images display orange color for the ZnO monolayer and yellow for the graphene substrate. ZnO coverage on graphene increases significantly with the number of ALD cycles (Figure 5c–e). As shown in Figure 5e, a ZnO monolayer deposited with 200 cycles exhibits highly uniform and high-quality thin films on a large-area graphene substrate. In order to confirm the compositional changes of the 20 and 200 ZnO ALD cycles on UV/ozone-treated graphene, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) were carried out. In the Raman spectra of the 200 cycles ZnO on graphene, distinct ZnO peaks were observed near 1131 and 1526 cm–1 (Supporting Figure 9). The X-ray diffraction patterns for the 200 cycles ALD grown ZnO on UV/ozone-treated graphene sample revealed [101̅0], [0002], and [101̅1] reflections of ZnO (Supporting Figure 10). XPS was also performed for the 20 and 200 ZnO ALD cycles on UV/ozone-treated graphene on SiO2/Si substrates (Supporting Figure 11). The peak of 1,022 eV in the spectra is corresponding to the Zn–O bonds (Supporting Figure 11a). Also, oxygen 1s spectra at 530.8 eV show O2– ions in the Zn–O bonding of the ZnO film (Supporting Figure 11b). The other peaks located at 532.1 eV correspond to the oxygen atoms bonded to the zinc in the ZnO. We performed STEM HAADF imaging and EELS analysis. The EELS confirmed the presence of Zn and O by the presence of the O K-edge and Zn L-edge of the ZnO monolayer on graphene (Supporting Figure 12). In addition, the compositional analysis of ZnO monolayer was performed using a time-of-flight secondary ion mass spectrometry (TOF-SIMS). The TOF-SIMS maps show ZnO growth areas in yellow. ZnO coverage on graphene was enlarged as the ALD cycles increased (Supporting Figure 14a-c). Parts f–h of Figures 5 show ARTEM images of ZnO nanostructures grown on graphene with 10, 20, and 200 ALD cycles. As shown in Figure 5f, ZnO with 10 ALD cycles starts to develop nanoclusters of 1–2 nm in diameters. The diffraction pattern in the inset of Figure 5f shows mostly spot patterns of graphene because of the insufficient amount of crystalline ZnO. Figure 5g shows that the ZnO monolayer cluster gradually grows in size, by 2–3 nm in diameter. After 200 ALD cycles, coalescence takes place over the entire area of graphene and ZnO nanoclusters merge into larger grains, resulting in the formation of grain boundaries (Figure 5h). The diffraction patterns in the inset of Figure 5h shows the mixed spot patterns of nanosized polycrystalline ZnO and graphene.
In summary, we demonstrate the formation of ZnO monolayer on graphene, which is the thinnest heteroepitaxial layer of semiconducting oxide on monolayer graphene. The optimized UV/ozone treatment enhances the hydrophilicity of the graphene substrate without deteriorating its electrical properties due to lattice damage, and enables the epitaxial growth of ZnO. Through ARTEM investigation, the ZnO monolayer on graphene is directly observed at the atomic scale and its heterostructure is confirmed through image simulation. Most notably, we clearly show the in situ atom-by-atom growth of zinc and oxygen at the zigzag edge of the ZnO monolayer on graphene at the atomic scale. Both ARTEM observation and the calculation confirm that oxygen-terminated zigzag edges are more stable than zinc-terminated zigzag and armchair edges. We determine that two dominant misorientation angles (0° and 30°) are associated with the epitaxial growth of the ZnO monolayer on graphene and that the misorientation angle of 0° becomes more prominent as the ZnO monolayer grows. Moreover, we experimentally determine that the monolayer ZnO on graphene has a wide band gap of up to 4.0 eV, which is different from that of other ZnO nanostructures, due to the quantum confinement effect and the crystallographic structure. The heteroepitaxial stack of the thinnest 2D oxide semiconductors on graphene has potential for future optoelectronic device applications associated with high optical transparency and flexibility. This study can lead to a new class of 2D heterostructures including semiconducting oxides formed by highly controlled epitaxial growth through a deposition route.
Supporting Information
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.nanolett.6b03621.
Experimental methods and additional data (PDF)
Supporting Movie 1, showing time-elapsed images of adsorbed ZnO adatoms on a graphene substrate (AVI)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
Acknowledgment
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2015R1A2A2A01006992, No. 2014R1A1A2055685), Nano Material Technology Development Program (2012M3A7B4049807) and IBS-R019-D1. S.K.K acknowledges the computation resources form UNIST-HPC and KISTI-PLSI. R.E. acknowledges funding from the European Research Council (ERC) under EU’s Horizon 2020 program (grant agreement No. 681312).
References
This article references 47 other publications.
- 1Choi, D.; Choi, M. Y.; Choi, W. M.; Shin, H. J.; Park, H. K.; Seo, J. S.; Park, J.; Yoon, S. M.; Chae, S. J.; Lee, Y. H.; Kim, S. W.; Choi, J. Y.; Lee, S. Y.; Kim, J. M. Adv. Mater. 2010, 22, 2187– 2192 DOI: 10.1002/adma.200903815Google ScholarThere is no corresponding record for this reference.
- 2Chung, K.; Lee, C. H.; Yi, G. C. Science 2010, 330, 655– 657 DOI: 10.1126/science.1195403Google ScholarThere is no corresponding record for this reference.
- 3Lee, C. H.; Kim, Y. J.; Hong, Y. J.; Jeon, S. R.; Bae, S.; Hong, B. H.; Yi, G. C. Adv. Mater. 2011, 23, 4614– 4619 DOI: 10.1002/adma.201102407Google ScholarThere is no corresponding record for this reference.
- 4Carcia, P. F.; McLean, R. S.; Reilly, M. H.; Nunes, G. Appl. Phys. Lett. 2003, 82, 1117– 1119 DOI: 10.1063/1.1553997Google ScholarThere is no corresponding record for this reference.
- 5Pearton, S. J.; Norton, D. P.; Ip, K.; Heo, Y. W.; Steiner, T. Superlattices Microstruct. 2003, 34, 3– 32 DOI: 10.1016/S0749-6036(03)00093-4Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXkt1Kisbs%253D&md5=fe9dfd1e40835dfa9affb594fee6e54eRecent progress in processing and properties of ZnOPearton, S. J.; Norton, D. P.; Ip, K.; Heo, Y. W.; Steiner, T.Superlattices and Microstructures (2003), 34 (1-2), 3-32CODEN: SUMIEK; ISSN:0749-6036. (Elsevier Science B.V.)A review. ZnO is attracting considerable attention for its possible application to UV light emitters, spin functional devices, gas sensors, transparent electronics and surface acoustic wave devices. There is also interest in integrating ZnO with other wide bandgap ceramic semiconductors such as the AlInGaN system. In this paper we summarize recent progress in doping control, materials processing methods such as dry etching and ohmic and Schottky contact formation, new understanding of the role of hydrogen and finally the prospects for control of ferromagnetism in transition metal-doped ZnO.
- 6Nomura, K.; Ohta, H.; Ueda, K.; Kamiya, T.; Hirano, M.; Hosono, H. Science 2003, 300, 1269– 1272 DOI: 10.1126/science.1083212Google ScholarThere is no corresponding record for this reference.
- 7Wang, Z. L. J. Phys.: Condens. Matter 2004, 16, R829– R858 DOI: 10.1088/0953-8984/16/25/R01Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXmtVyhtLY%253D&md5=333d82c73e4a8bde059791cf54e03bb7Zinc oxide nanostructures: Growth, properties and applicationsWang, Zhong LinJournal of Physics: Condensed Matter (2004), 16 (25), R829-R858CODEN: JCOMEL; ISSN:0953-8984. (Institute of Physics Publishing)A review. Zinc oxide is a unique material that exhibits semiconducting and piezoelec. dual properties. Using a solid-vapor phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobelts, nanowires and nanocages of ZnO were synthesized under specific growth conditions. These unique nanostructures unambiguously demonstrate that ZnO probably has the richest family of nanostructures among all materials, both in structures and in properties. The nanostructures could have novel applications in optoelectronics, sensors, transducers and biomedical sciences. This article reviews the various nanostructures of ZnO grown by the solid-vapor phase technique and their corresponding growth mechanisms. The application of ZnO nanobelts as nanosensors, nanocantilevers, field effect transistors and nanoresonators is demonstrated.
- 8Freeman, C. L.; Claeyssens, F.; Allan, N. L.; Harding, J. H. Phys. Rev. Lett. 2006, 96, 066102 DOI: 10.1103/PhysRevLett.96.066102Google ScholarThere is no corresponding record for this reference.
- 9Tu, Z. C.; Hu, X. Phys. Rev. B: Condens. Matter Mater. Phys. 2006, 74, 035434 DOI: 10.1103/PhysRevB.74.035434Google ScholarThere is no corresponding record for this reference.
- 10Tusche, C.; Meyerheim, H. L.; Kirschner, J. Phys. Rev. Lett. 2007, 99, 026102 DOI: 10.1103/PhysRevLett.99.026102Google ScholarThere is no corresponding record for this reference.
- 11Quang, H. T.; Bachmatiuk, A.; Dianat, A.; Ortmann, F.; Zhao, J.; Warner, J. H.; Eckert, J.; Cunniberti, G.; Rummeli, M. H. ACS Nano 2015, 9, 11408– 11413 DOI: 10.1021/acsnano.5b05481Google ScholarThere is no corresponding record for this reference.
- 12Lee, J.; Sorescu, D. C.; Deng, X. J. Phys. Chem. Lett. 2016, 7, 1335– 1340 DOI: 10.1021/acs.jpclett.6b00432Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xlt1Sksro%253D&md5=21821a872f128003d83c7865369e5d3bTunable Lattice Constant and Band Gap of Single- and Few-Layer ZnOLee, Junseok; Sorescu, Dan C.; Deng, XingyiJournal of Physical Chemistry Letters (2016), 7 (7), 1335-1340CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)Single and few-layer ZnO(0001) (ZnO(nL), n = 1-4) grown on Au(111) were characterized via scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and d. functional theory (DFT) calcns. The in-plane lattice consts. of the ZnO(nL, n ≤ 3) are expanded compared to that of the bulk wurtzite ZnO(0001). The lattice const. reaches a max. expansion of 3% in the ZnO(2L) and decreases to the bulk wurtzite ZnO value in the ZnO(4L). The band gap decreases monotonically with increasing no. of ZnO layers from 4.48 eV (ZnO(1L)) to 3.42 eV (ZnO(4L)). Probably a transition from a planar to the bulk-like ZnO structure occurs around the thickness of ZnO(4L). Also the lattice const. and the band gap in ultrathin ZnO can be tuned by controlling the no. of layers, providing a basis for further study of this material.
- 13Demel, J.; Pleštil, J.; Bezdička, P.; Janda, P.; Klementová, M.; Lang, K. J. Phys. Chem. C 2011, 115, 24702– 24706 DOI: 10.1021/jp209973tGoogle ScholarThere is no corresponding record for this reference.
- 14Kim, Y. J.; Lee, J. H.; Yi, G. C. Appl. Phys. Lett. 2009, 95, 213101 DOI: 10.1063/1.3266836Google ScholarThere is no corresponding record for this reference.
- 15Akhavan, O. ACS Nano 2010, 4, 4174– 4180 DOI: 10.1021/nn1007429Google ScholarThere is no corresponding record for this reference.
- 16Kim, Y. J.; Hadiyawarman; Yoon, A.; Kim, M.; Yi, G. C.; Liu, C. Nanotechnology 2011, 22, 245603 DOI: 10.1088/0957-4484/22/24/245603Google ScholarThere is no corresponding record for this reference.
- 17Yin, Z.; Wu, S.; Zhou, X.; Huang, X.; Zhang, Q.; Boey, F.; Zhang, H. Small 2010, 6, 307– 312 DOI: 10.1002/smll.200901968Google ScholarThere is no corresponding record for this reference.
- 18Wu, S. X.; Yin, Z. Y.; He, Q. Y.; Huang, X. A.; Zhou, X. Z.; Zhang, H. J. Phys. Chem. C 2010, 114, 11816– 11821 DOI: 10.1021/jp103696uGoogle ScholarThere is no corresponding record for this reference.
- 19Xu, C.; Lee, J.-H.; Lee, J.-C.; Kim, B.-S.; Hwang, S. W.; Whang, D. CrystEngComm 2011, 13, 6036– 6039 DOI: 10.1039/c1ce05695fGoogle ScholarThere is no corresponding record for this reference.
- 20Viswanatha, R.; Sapra, S.; Satpati, B.; Satyam, P. V.; Dev, B. N.; Sarma, D. D. J. Mater. Chem. 2004, 14, 661– 668 DOI: 10.1039/b310404dGoogle ScholarThere is no corresponding record for this reference.
- 21Kukreja, L. M.; Misra, P.; Fallert, J.; Sartor, J.; Kalt, H.; Klingshirn, C. Ieee 2008, 61– 66 DOI: 10.1109/IPGC.2008.4781315Google ScholarThere is no corresponding record for this reference.
- 22Saito, R.; Fujita, M.; Dresselhaus, G.; Dresselhaus, M. S. Appl. Phys. Lett. 1992, 60, 2204– 2206 DOI: 10.1063/1.107080Google Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK38XktFCmtbk%253D&md5=5a9f5a777141c128585471c4b16e7a34Electronic structure of chiral graphene tubulesSaito, R.; Fujita, M.; Dresselhaus, G.; Dresselhaus, M. S.Applied Physics Letters (1992), 60 (18), 2204-6CODEN: APPLAB; ISSN:0003-6951.The electronic structure for graphene monolayer tubules is predicted as a function of the diam. and helicity of the constituent graphene tubules. The calcd. results show that approx. 1/3 of these tubules are a one-dimensional metal which is stable against a Peierls distortion, and the other 2/3 are one-dimensional semiconductors. The implications of these results are discussed.
- 23Geim, A. K.; Novoselov, K. S. Nat. Mater. 2007, 6, 183– 191 DOI: 10.1038/nmat1849Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXit1Khtrg%253D&md5=c2c02ce70a1725e6c559c173156568c5The rise of grapheneGeim, A. K.; Novoselov, K. S.Nature Materials (2007), 6 (3), 183-191CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)A review. Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when com. products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top expts. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.
- 24Castro Neto, A. H.; Guinea, F.; Peres, N. M. R.; Novoselov, K. S.; Geim, A. K. Rev. Mod. Phys. 2009, 81, 109– 162 DOI: 10.1103/RevModPhys.81.109Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXksVamsLY%253D&md5=d4b07bf6507d26df9b0447a25131bf18The electronic properties of grapheneCastro Neto, A. H.; Guinea, F.; Peres, N. M. R.; Novoselov, K. S.; Geim, A. K.Reviews of Modern Physics (2009), 81 (1), 109-162CODEN: RMPHAT; ISSN:0034-6861. (American Physical Society)A review. This article reviews the basic theor. aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations. The Dirac electrons can be controlled by application of external elec. and magnetic fields, or by altering sample geometry and/or topol. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and no. of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the phys. properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron-electron and electron-phonon interactions in single layer and multilayer graphene are also presented.
- 25Bolotin, K. I.; Sikes, K. J.; Jiang, Z.; Klima, M.; Fudenberg, G.; Hone, J.; Kim, P.; Stormer, H. L. Solid State Commun. 2008, 146, 351– 355 DOI: 10.1016/j.ssc.2008.02.024Google Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXls12qu7s%253D&md5=eb2106037936ae4e92f258596283c0c0Ultrahigh electron mobility in suspended grapheneBolotin, K. I.; Sikes, K. J.; Jiang, Z.; Klima, M.; Fudenberg, G.; Hone, J.; Kim, P.; Stormer, H. L.Solid State Communications (2008), 146 (9-10), 351-355CODEN: SSCOA4; ISSN:0038-1098. (Elsevier Ltd.)We have achieved mobilities in excess of 200,000 cm2 V -1 s-1 at electron densities of ∼2 × 1011 cm-2 by suspending single layer graphene. Suspension ∼150 nm above a Si/SiO2 gate electrode and elec. contacts to the graphene was achieved by a combination of electron beam lithog. and etching. The specimens were cleaned in situ by employing current-induced heating, directly resulting in a significant improvement of elec. transport. Concomitant with large mobility enhancement, the widths of the characteristic Dirac peaks are reduced by a factor of 10 compared to traditional, nonsuspended devices. This advance should allow for accessing the intrinsic transport properties of graphene.
- 26Wang, F.; Zhang, Y. B.; Tian, C. S.; Girit, C.; Zettl, A.; Crommie, M.; Shen, Y. R. Science 2008, 320, 206– 209 DOI: 10.1126/science.1152793Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXktlGjt7k%253D&md5=770b5df8c29893a3a42a776ebadec5dbGate-variable optical transitions in grapheneWang, Feng; Zhang, Yuanbo; Tian, Chuanshan; Girit, Caglar; Zettl, Alex; Crommie, Michael; Shen, Y. RonScience (Washington, DC, United States) (2008), 320 (5873), 206-209CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Two-dimensional graphene monolayers and bilayers exhibit fascinating elec. transport behaviors. Using IR spectroscopy, we find that they also have strong interband transitions and that their optical transitions can be substantially modified through elec. gating, much like elec. transport in field-effect transistors. This gate dependence of interband transitions adds a valuable dimension for optically probing graphene band structure. For a graphene monolayer, it yields directly the linear band dispersion of Dirac fermions, whereas in a bilayer, it reveals a dominating van Hove singularity arising from interlayer coupling. The strong and layer-dependent optical transitions of graphene and the tunability by simple elec. gating hold promise for new applications in IR optics and optoelectronics.
- 27Gokus, T.; Nair, R. R.; Bonetti, A.; Bohmler, M.; Lombardo, A.; Novoselov, K. S.; Geim, A. K.; Ferrari, A. C.; Hartschuh, A. ACS Nano 2009, 3, 3963– 3968 DOI: 10.1021/nn9012753Google Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsVClurfE&md5=83c292793381972d9f1e7e96b4c7b855Making Graphene Luminescent by Oxygen Plasma TreatmentGokus, T.; Nair, R. R.; Bonetti, A.; Bohmler, M.; Lombardo, A.; Novoselov, K. S.; Geim, A. K.; Ferrari, A. C.; Hartschuh, A.ACS Nano (2009), 3 (12), 3963-3968CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Strong photoluminescence (PL) can be induced in single-layer graphene using an O plasma treatment. The PL is spatially uniform across the flakes and connected to elastic scattering spectra distinctly different from those of gapless pristine graphene. O plasma can be used to selectively convert the topmost layer when multilayer samples are treated.
- 28Shin, Y. J.; Wang, Y.; Huang, H.; Kalon, G.; Wee, A. T. S.; Shen, Z.; Bhatia, C. S.; Yang, H. Langmuir 2010, 26, 3798– 3802 DOI: 10.1021/la100231uGoogle ScholarThere is no corresponding record for this reference.
- 29Lee, B.; Park, S.-Y.; Kim, H.-C.; Cho, K.; Vogel, E. M.; Kim, M. J.; Wallace, R. M.; Kim, J. Appl. Phys. Lett. 2008, 92, 203102 DOI: 10.1063/1.2928228Google ScholarThere is no corresponding record for this reference.
- 30Leconte, N.; Moser, J.; Ordejon, P.; Tao, H. H.; Lherbier, A.; Bachtold, A.; Alsina, F.; Sotomayor Torres, C. M.; Charlier, J. C.; Roche, S. ACS Nano 2010, 4, 4033– 4038 DOI: 10.1021/nn100537zGoogle ScholarThere is no corresponding record for this reference.
- 31Liu, L.; Ryu, S. M.; Tomasik, M. R.; Stolyarova, E.; Jung, N.; Hybertsen, M. S.; Steigerwald, M. L.; Brus, L. E.; Flynn, G. W. Nano Lett. 2008, 8, 1965– 1970 DOI: 10.1021/nl0808684Google ScholarThere is no corresponding record for this reference.
- 32Xu, Z.; Ao, Z.; Chu, D.; Younis, A.; Li, C. M.; Li, S. Sci. Rep. 2014, 4, 6450 DOI: 10.1038/srep06450Google Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXksVyqs78%253D&md5=42cb4898614196d00262b002a4fd7c45Reversible Hydrophobic to Hydrophilic Transition in Graphene via Water Splitting Induced by UV IrradiationXu, Zhemi; Ao, Zhimin; Chu, Dewei; Younis, Adnan; Li, Chang Ming; Li, SeanScientific Reports (2014), 4 (), 6450CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Although the reversible wettability transition between hydrophobic and hydrophilic graphene under UV irradn. has been obsd., the mechanism for this phenomenon remains unclear. In this work, exptl. and theor. investigations demonstrate that the H2O mols. are split into hydrogen and hydroxyl radicals, which are then captured by the graphene surface through chem. binding in an ambient environment under UV irradn. The dissociative adsorption of H2O mols. induces the wettability transition in graphene from hydrophobic to hydrophilic. Our discovery may hold promise for the potential application of graphene in water splitting.
- 33Liu, H.; Liu, Y.; Zhu, D. J. Mater. Chem. 2011, 21, 3335– 3345 DOI: 10.1039/C0JM02922JGoogle Scholar33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXit1ymsrw%253D&md5=29b3a40cfb5efd00092e3a579dfca24fChemical doping of grapheneLiu, Hongtao; Liu, Yunqi; Zhu, DaobenJournal of Materials Chemistry (2011), 21 (10), 3335-3345CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)A review. Recently, a lot of effort has been focused on improving the performance and exploring the elec. properties of graphene. A review with 153 refs. This article presents a summary of chem. doping of graphene aimed at tuning the electronic properties of graphene. p-Type and n-type doping of graphene achieved through surface transfer doping or substitutional doping and their applications based on doping are reviewed. Chem. doping for band gap tuning in graphene is also presented. It will be beneficial to designing high performance electronic devices based on chem. doped graphene.
- 34Jiang, Q. G.; Ao, Z. M.; Chu, D. W.; Jiang, Q. J. Phys. Chem. C 2012, 116, 19321– 19326 DOI: 10.1021/jp3050466Google ScholarThere is no corresponding record for this reference.
- 35Huh, S.; Park, J.; Kim, Y. S.; Kim, K. S.; Hong, B. H.; Nam, J. M. ACS Nano 2011, 5, 9799– 9806 DOI: 10.1021/nn204156nGoogle ScholarThere is no corresponding record for this reference.
- 36Mulyana, Y.; Uenuma, M.; Ishikawa, Y.; Uraoka, Y. J. Phys. Chem. C 2014, 118, 27372– 27381 DOI: 10.1021/jp508026gGoogle ScholarThere is no corresponding record for this reference.
- 37Wang, W.; Ruiz, I.; Lee, I.; Zaera, F.; Ozkan, M.; Ozkan, C. S. Nanoscale 2015, 7, 7045– 7050 DOI: 10.1039/C4NR06795AGoogle ScholarThere is no corresponding record for this reference.
- 38Jiang, B.; Zhang, C.; Jin, C.; Wang, H.; Chen, X.; Zhan, H.; Huang, F.; Kang, J. Cryst. Growth Des. 2012, 12, 2850– 2855 DOI: 10.1021/cg201727tGoogle Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XmvFGntbo%253D&md5=bc1ac9ed21378e267c613771ddac5942Kinetic-Dynamic Properties of Different Monomers and Two-Dimensional Homoepitaxy Growth on the Zn-Polar (0001) ZnO SurfaceJiang, Baofeng; Zhang, Chunmiao; Jin, Changlian; Wang, Huiqiong; Chen, Xiaohang; Zhan, Huahan; Huang, Feng; Kang, JunyongCrystal Growth & Design (2012), 12 (6), 2850-2855CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)Homoepitaxy ZnO monolayer growth was studied from dynamics to kinetics taking ZnO mols. and Zn-O cluster monomers into account in the atomistic growth by 1st-principles calcns. and Monte Carlo simulations and compared with exptl. growth by MBE. Theor., the ZnO mols. scatter equivalently on both the wurtzite sites (WSs) and zincblende sites (ZSs) and stick even at high temps. The Zn3O1 monomers resulted in a larger island size and a higher compact degree and the growth approached to the two-dimensional mode at high temp.; the film structure finalized in the single wurtzite phase structure with more vacancies, which agreed with the in situ scanning tunnel microscopy observation for the growth in Zn-rich conditions to form Zn3O1 monomers. For the Zn1O3 monomers, the transformation from ZSs to WSs was more difficult even with temp. increase and they could locate at both WSs and ZSs, consistent with the in situ RHEED for the growth in O-rich conditions to form Zn1O3 monomers. Combining the advantages of both cluster monomers, a two step-growth technique was developed by alternatively supplying Zn and O. The resultant ZnO films exhibited flat texture and uniform phase structure as indicated by the at. steps in the STM images and the streaky RHEED patterns.
- 39Peng, Z. A.; Peng, X. G. J. Am. Chem. Soc. 2002, 124, 3343– 3353 DOI: 10.1021/ja0173167Google ScholarThere is no corresponding record for this reference.
- 40Kohler, U.; Dorna, V.; Jensen, C.; Kneppe, M.; Piaszenski, G.; Reshoft, K.; Wolf, C. Elsevier Science Bv 2004, 391– 412 DOI: 10.1016/B978-044451386-1/50020-9Google ScholarThere is no corresponding record for this reference.
- 41Jo, J.; Yoo, H.; Park, S. I.; Park, J. B.; Yoon, S.; Kim, M.; Yi, G. C. Adv. Mater. 2014, 26, 2011– 2015 DOI: 10.1002/adma.201304720Google ScholarThere is no corresponding record for this reference.
- 42Dulub, O.; Diebold, U.; Kresse, G. Phys. Rev. Lett. 2003, 90, 016102 DOI: 10.1103/PhysRevLett.90.016102Google ScholarThere is no corresponding record for this reference.
- 43Lauritsen, J. V.; Porsgaard, S.; Rasmussen, M. K.; Jensen, M. C. R.; Bechstein, R.; Meinander, K.; Clausen, B. S.; Helveg, S.; Wahl, R.; Kresse, G.; Besenbacher, F. ACS Nano 2011, 5, 5987– 5994 DOI: 10.1021/nn2017606Google ScholarThere is no corresponding record for this reference.
- 44Ryu, G. H.; Park, H. J.; Ryou, J.; Park, J.; Lee, J.; Kim, G.; Shin, H. S.; Bielawski, C. W.; Ruoff, R. S.; Hong, S.; Lee, Z. Nanoscale 2015, 7, 10600– 10605 DOI: 10.1039/C5NR01473EGoogle ScholarThere is no corresponding record for this reference.
- 45Rafferty, B.; Brown, L. M. Phys. Rev. B: Condens. Matter Mater. Phys. 1998, 58, 10326– 10337 DOI: 10.1103/PhysRevB.58.10326Google ScholarThere is no corresponding record for this reference.
- 46Kim, E.; Jiang, Z. T.; No, K. Jpn. J. Appl. Phys. 2000, 39, 4820– 4825 DOI: 10.1143/JJAP.39.4820Google Scholar46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXmtFymsLo%253D&md5=0d347d836e7b295d4f55c8b7f4a962f0Measurement and calculation of optical band gap of chromium aluminum oxide filmsKim, Eunah; Jiang, Zhong-Tao; No, KwangsooJapanese Journal of Applied Physics, Part 1: Regular Papers, Short Notes & Review Papers (2000), 39 (8), 4820-4825CODEN: JAPNDE; ISSN:0021-4922. (Japan Society of Applied Physics)The optical band gap is a basic property of optical materials. The measured band gap depends not only on the material but also on its characteristics such as crystallinity and stoichiometry. The optical band gap of chromium aluminum oxide films was measured and calcd. by three different methods. Firstly, the conventional exptl.-graphical method is used. This method is applicable only to an all-cryst. phase or an all-amorphous phase. Secondly, an exptl.-calcn. method applicable to films composed of both cryst. and amorphous phases was used. The authors calcd. the optical band gap between the HOMO of O2p and the LUMO of Cr3d in Cr1.71Al0.29O3 films composed of both amorphous and cryst. phases. A band gap for the d-d transition was obtained. The measured value was compared with the theor. optical band gap calcd. by the discrete variational-Xα (DV-Xα) method.
- 47Kim, K.; Lee, H. B.; Johnson, R. W.; Tanskanen, J. T.; Liu, N.; Kim, M. G.; Pang, C.; Ahn, C.; Bent, S. F.; Bao, Z. Nat. Commun. 2014, 5, 4781 DOI: 10.1038/ncomms5781Google Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2M%252Fns1GisQ%253D%253D&md5=180112be723f8fcda3c065997157c751Selective metal deposition at graphene line defects by atomic layer depositionKim Kwanpyo; Lee Han-Bo-Ram; Johnson Richard W; Tanskanen Jukka T; Liu Nan; Bent Stacey F; Bao Zhenan; Kim Myung-Gil; Pang Changhyun; Ahn ChiyuiNature communications (2014), 5 (), 4781 ISSN:.One-dimensional defects in graphene have a strong influence on its physical properties, such as electrical charge transport and mechanical strength. With enhanced chemical reactivity, such defects may also allow us to selectively functionalize the material and systematically tune the properties of graphene. Here we demonstrate the selective deposition of metal at chemical vapour deposited graphene's line defects, notably grain boundaries, by atomic layer deposition. Atomic layer deposition allows us to deposit Pt predominantly on graphene's grain boundaries, folds and cracks due to the enhanced chemical reactivity of these line defects, which is directly confirmed by transmission electron microscopy imaging. The selective functionalization of graphene defect sites, together with the nanowire morphology of deposited Pt, yields a superior platform for sensing applications. Using Pt-graphene hybrid structures, we demonstrate high-performance hydrogen gas sensors at room temperature and show its advantages over other evaporative Pt deposition methods, in which Pt decorates the graphene surface non-selectively.
Cited By
Smart citations by scite.ai include citation statements extracted from the full text of the citing article. The number of the statements may be higher than the number of citations provided by ACS Publications if one paper cites another multiple times or lower if scite has not yet processed some of the citing articles.
This article is cited by 128 publications.
- Mandeep Singh, Muhammad Zakria, Amandeep Singh Pannu, Prashant Sonar, Christopher Smith, Sanje Mahasivam, Rajesh Ramanathan, Kevin Tran, Sherif Tawfik, Billy James Murdoch, Edwin Lawrence Harrop Mayes, Michelle J. S. Spencer, Matthew R. Phillips, Vipul Bansal, Cuong Ton-That. Defect-Free, Few-Atomic-Layer Thin ZnO Nanosheets with Superior Excitonic Properties for Optoelectronic Devices. ACS Nano 2024, 18
(26)
, 16947-16957. https://doi.org/10.1021/acsnano.4c03098
- Dipali Nayak, R. Thangavel. Theoretical Investigation of Electronic and Photocatalytic Properties of a Trilayer vdW MoS2/ZnO/WS2 Heterojunction for Overall Water-Splitting Applications. ACS Applied Energy Materials 2024, 7
(7)
, 2642-2652. https://doi.org/10.1021/acsaem.3c02948
- Mariano Romero, Fernando Pignanelli, Dominique Mombrú, Ricardo Faccio, Álvaro W. Mombrú. Evidence of Graphene-like ZnO Nanostructures via Zinc Dimethoxide Hydrolysis–Condensation Under Ambient Conditions on a Au(111) Surface Using SERS: Simulation and Experiment. The Journal of Physical Chemistry C 2023, 127
(1)
, 429-436. https://doi.org/10.1021/acs.jpcc.2c07409
- Himanshu Tyagi, Tapaswini Dash, Akash Kumar Maharana, Jyoti Saini, Mamta Raturi, Kiran Shankar Hazra. Green-Lighting the Sub-Band Gap Excitation in Two-Dimensional Zinc Oxide. The Journal of Physical Chemistry Letters 2022, 13
(51)
, 12019-12025. https://doi.org/10.1021/acs.jpclett.2c03318
- Junjie Li, Francis Leonard Deepak. In Situ Kinetic Observations on Crystal Nucleation and Growth. Chemical Reviews 2022, 122
(23)
, 16911-16982. https://doi.org/10.1021/acs.chemrev.1c01067
- Gyu Hyun Jeong, Hye Soung Jang, Jong Chan Yoon, Zonghoon Lee, Jieun Yang, A-Rang Jang, Gyeong Hee Ryu. Morphologically Controlled Synthesis of Reduced-Dimensional ZnO/Zn(OH)2 Nanosheets. ACS Omega 2022, 7
(40)
, 35834-35839. https://doi.org/10.1021/acsomega.2c04108
- Kangsik Kim, Seungwoo Son, Seonwoo Lee, Jong-Hyun Ahn, Zonghoon Lee. Observation of the Initial Stage of 3C-SiC Heteroepitaxial Growth on the Si Nanomembrane. Crystal Growth & Design 2022, 22
(2)
, 1421-1426. https://doi.org/10.1021/acs.cgd.1c01372
- Parisa Marashizadeh, Mohammad Abshirini, Mrinal Saha, Liangliang Huang, Yingtao Liu. Atomistic Simulations on Structural Characteristics of ZnO Nanowire-Enhanced Graphene/Epoxy Polymer Composites: Implications for Lightweight Structures. ACS Applied Nano Materials 2021, 4
(11)
, 11770-11778. https://doi.org/10.1021/acsanm.1c02362
- Seungwoo Son, Yeonchoo Cho, Hyo-Ki Hong, Jongyeong Lee, Jung Hwa Kim, Kangsik Kim, Yeongdong Lee, Aram Yoon, Hyeon-Jin Shin, Zonghoon Lee. Spontaneous Formation of a ZnO Monolayer by the Redox Reaction of Zn on Graphene Oxide. ACS Applied Materials & Interfaces 2020, 12
(48)
, 54222-54229. https://doi.org/10.1021/acsami.0c18291
- Alex W. Robertson, Gun-Do Lee, Sungwoo Lee, Parker Buntin, Matthew Drexler, Ali A. Abdelhafiz, Euijoon Yoon, Jamie H. Warner, Faisal M. Alamgir. Atomic Structure and Dynamics of Epitaxial Platinum Bilayers on Graphene. ACS Nano 2019, 13
(10)
, 12162-12170. https://doi.org/10.1021/acsnano.9b06701
- Sapna Sinha, Yuewen Sheng, Ian Griffiths, Neil P. Young, Si Zhou, Angus I. Kirkland, Kyriakos Porfyrakis, Jamie H. Warner. In Situ Atomic-Level Studies of Gd Atom Release and Migration on Graphene from a Metallofullerene Precursor. ACS Nano 2018, 12
(10)
, 10439-10451. https://doi.org/10.1021/acsnano.8b06057
- Zhengyang Cai, Bilu Liu, Xiaolong Zou, Hui-Ming Cheng. Chemical Vapor Deposition Growth and Applications of Two-Dimensional Materials and Their Heterostructures. Chemical Reviews 2018, 118
(13)
, 6091-6133. https://doi.org/10.1021/acs.chemrev.7b00536
- Gang Zhang, Qingyu Hou, Zhenchao Xu, Wen Ma, Riguleng Si. First-principles study of the influence of coexistence of Zn vacancies (VZn) and H interstices (Hi) on the photoelectrocatalytic performance of wurtzite ZnO (001) monolayer: Li/Na/K. Vacuum 2025, 233 , 113981. https://doi.org/10.1016/j.vacuum.2024.113981
- Hoang Van Ngoc, Huynh Thi Phuong Thuy. Group I elements-adsorbed NiZnO monolayer: Electro-optical properties and potential applications. Physica B: Condensed Matter 2025, 700 , 416922. https://doi.org/10.1016/j.physb.2025.416922
- Junqing Wen, Miaomiao Wang, Guoxiang Chen, Jianmin Zhang. Study on the Electronic and Optical Properties of So2, Cl2 Adsorption on the Intrinsic and Modified G-Zno Mono-Layer. 2025https://doi.org/10.2139/ssrn.5096373
- Sulagna Ghosh, Palash Nath, Dirtha Sanyal. Adsorption and evolution of N2 molecules over ZnO monolayer: a combined DFT and kinetic Monte-Carlo insight. Adsorption 2024, 30
(8)
, 2255-2265. https://doi.org/10.1007/s10450-024-00551-x
- Delu Gao, Ruoqi Zhang, Dunyou Wang. CO oxidation on single Pt atom supported by two-dimensional ZnO monolayer: Reaction mechanism and precursor activation. Molecular Catalysis 2024, 569 , 114577. https://doi.org/10.1016/j.mcat.2024.114577
- Matteo Jugovac, Iulia Cojocariu, Vitaliy Feyer, Stefan Blügel, Gustav Bihlmayer, Paolo Perna. Spin-dependent electronic phenomena in heavily-doped monolayer graphene. Carbon 2024, 230 , 119666. https://doi.org/10.1016/j.carbon.2024.119666
- Areg Hunanyan, Nane Petrosyan, Hayk Zakaryan. Gas sensing properties of two dimensional tin oxides: A DFT study. Applied Surface Science 2024, 672 , 160814. https://doi.org/10.1016/j.apsusc.2024.160814
- Si-Lie Fu, Xue‑Lian Gao, Chun‑An Wang, Geng‑Run Gan, Ya‑Peng Xie, Yu-Lin Chen, Jia-Ying Chen, Lin‑Han Wang, Xian-Qiu Wu. Adsorption of NO on ZnO monolayer doped with transition metal (Ti, V, Cr, Mn, Co, and Zr): The first-principles study. Chemical Physics Letters 2024, 846 , 141327. https://doi.org/10.1016/j.cplett.2024.141327
- Fernando Pignanelli, Mariano Romero, Ricardo Faccio, Álvaro W. Mombrú. The lithiation mechanism of ultrathin 2D ZnO systems working as anode materials for lithium-ion batteries: From Wurtzite to graphene-like structures. Surfaces and Interfaces 2024, 46 , 103997. https://doi.org/10.1016/j.surfin.2024.103997
- Rongzhi Wang, Jin-Cheng Zheng. ZnO monolayer-supported single atom catalysts for efficient electrocatalytic hydrogen evolution reaction. Physical Chemistry Chemical Physics 2024, 26
(7)
, 5848-5857. https://doi.org/10.1039/D3CP05241A
- Anbing Zhang, Shi Qiu, Luneng Zhao, Hongsheng Liu, Jijun Zhao, Junfeng Gao. Robust Type‐II Band Alignment and Stacking‐Controlling Second Harmonic Generation in GaN/ZnO vdW Heterostructure. Laser & Photonics Reviews 2024, 18
(2)
https://doi.org/10.1002/lpor.202300742
- Xiao Wang, Hongyu Zhang, Wen Yu. The study of electronic and optical properties of
ZnO
/
MoS
2
and its vacancy heterostructures by first principles. International Journal of Quantum Chemistry 2024, 124
(1)
https://doi.org/10.1002/qua.27329
- Lanli Chen, Hongduo Hu, Aiping Wang, Zhihua Xiong, Yuanyuan Cui. Density functional theory study of adsorption of organic molecules on ZnO monolayers: Implications for conduction type and electrical characteristics. Results in Physics 2024, 56 , 107225. https://doi.org/10.1016/j.rinp.2023.107225
- Dong Han, Xian-Bin Li, Nian-Ke Chen, Dan Wang, Sheng-Yi Xie, Xue-Jiao Chen, De-Zhen Shen. Thickness-dependent atomic structures of two-dimensional few-layer ZnO: A density functional theory study. Physical Review B 2024, 109
(1)
https://doi.org/10.1103/PhysRevB.109.014105
- Carlos Morales, Ali Mahmoodinezhad, Rudi Tschammer, Julia Kosto, Carlos Alvarado Chavarin, Markus Andreas Schubert, Christian Wenger, Karsten Henkel, Jan Ingo Flege. Combination of Multiple Operando and In-Situ Characterization Techniques in a Single Cluster System for Atomic Layer Deposition: Unraveling the Early Stages of Growth of Ultrathin Al2O3 Films on Metallic Ti Substrates. Inorganics 2023, 11
(12)
, 477. https://doi.org/10.3390/inorganics11120477
- S. Laghzaoui, A. Fakhim Lamrani, R. Ahl Laamara. Excellent optical and thermoelectric features of two-dimensional half-metallic ferromagnet Zn1-x(TM)xO: A first principle investigation. Physica B: Condensed Matter 2023, 668 , 415241. https://doi.org/10.1016/j.physb.2023.415241
- Lixuesong Han, Tingting Cheng, Yiran Ding, Mengqi Zeng, Lei Fu. Recent progress in synthesis and properties of 2D room-temperature ferromagnetic materials. Science China Chemistry 2023, 66
(11)
, 3054-3069. https://doi.org/10.1007/s11426-023-1767-2
- Pankaj Kumar, Debesh R. Roy. Elastic, Optical, and Thermoelectric Properties of 2D Square Lattice and Hexagonal Zinc Chalcogenides under First‐Principles Calculations. physica status solidi (b) 2023, 260
(10)
https://doi.org/10.1002/pssb.202300046
- Mian Azmat, Abdul Majid, Mohammad Alkhedher, Sajjad Haider, Muhammad Saeed Akhtar. A first-principles study on two-dimensional tetragonal samarium nitride as a novel photocatalyst for hydrogen production. International Journal of Hydrogen Energy 2023, 48
(79)
, 30732-30740. https://doi.org/10.1016/j.ijhydene.2023.04.248
- Masoumeh Mohammadzaheri, Saeed Jamehbozorgi, Maosud Darvish Ganji, Mahyar Rezvani, Zahra Javanshir. Toward functionalization of ZnO nanotubes and monolayers with 5-aminolevulinic acid drugs as possible nanocarriers for drug delivery: a DFT based molecular dynamic simulation. Physical Chemistry Chemical Physics 2023, 25
(32)
, 21492-21508. https://doi.org/10.1039/D3CP01490H
- Kanokwan Kanchiang, Sittichian Pramchu. First-principles study on the electronic structure of siligraphene on a ZnO monolayer. Journal of Applied Crystallography 2023, 56
(4)
, 1091-1098. https://doi.org/10.1107/S1600576723005277
- Zijian Hu, Xiance Xie, Zhihong Yang, Yunhui Wang, Shicheng Jiang. Orientation-Dependent High-Order Harmonic Generation from Monolayer ZnO. Symmetry 2023, 15
(7)
, 1427. https://doi.org/10.3390/sym15071427
- Chen Zhao, Lijian Li, Yingtao Zhu, Long Zhang. Performance study of photocatalytic hydrogen production from ZnO double-walled nanotubes based on density functional theory. Computational and Theoretical Chemistry 2023, 1225 , 114179. https://doi.org/10.1016/j.comptc.2023.114179
- Ivan Shtepliuk. Defect-Induced Modulation of a 2D ZnO/Graphene Heterostructure: Exploring Structural and Electronic Transformations. Applied Sciences 2023, 13
(12)
, 7243. https://doi.org/10.3390/app13127243
- Lin Li, Jianpei Wang, Ping Yang. Graphene/Janus ZnO heterostructure to build highly efficient photovoltaic properties. Diamond and Related Materials 2023, 136 , 110037. https://doi.org/10.1016/j.diamond.2023.110037
- Saumen Chaudhuri, A. K. Das, G. P. Das, B. N. Dev. Ab Initio Study of Electronic and Lattice Dynamical Properties of Monolayer ZnO Under Strain. Journal of Electronic Materials 2023, 52
(3)
, 1633-1643. https://doi.org/10.1007/s11664-022-09938-4
- Brahim Marfoua, Jisang Hong. Graphene Induced High Thermoelectric Performance in ZnO/Graphene Heterostructure. Advanced Materials Interfaces 2023, 10
(7)
https://doi.org/10.1002/admi.202202387
- Lanli Chen, Hongduo Hu, Aiping Wang, Zhihua Xiong, Yuanyuan Cui, Yanfeng Gao. Tuning the atomic structures and electronic properties of two-dimensional C60/ZnO materials via external impacts. Applied Surface Science 2023, 612 , 155857. https://doi.org/10.1016/j.apsusc.2022.155857
- Dipali Nayak, R. Thangavel. Insight into enhanced photocatalytic properties of a type-II MoS
2
/ZnO heterostructure and tuning its properties and interfacial charge transfer by strain. New Journal of Chemistry 2023, 47
(7)
, 3328-3340. https://doi.org/10.1039/D2NJ05606B
- Brahim Marfoua, Jisang Hong. Origin of room temperature ferromagnetism in optically transparent 2D graphene/Co-doped ZnO/graphene. Applied Surface Science 2023, 611 , 155746. https://doi.org/10.1016/j.apsusc.2022.155746
- Hong-Ji Wang, Jun-Tao Yang, Chang-Ju Xu, Hai-Ming Huang, Qing Min, Yong-Chen Xiong, Shi-Jun Luo. Investigations on structural, electronic and optical properties of ZnO in two-dimensional configurations by first-principles calculations. Journal of Physics: Condensed Matter 2023, 35
(1)
, 014002. https://doi.org/10.1088/1361-648X/ac9d17
- Yi Liu, Xiaolan Yang. Effects of Fe doping on the magnetic and absorption spectrum of graphene-like ZnO monolayer from first-principles calculations. Chemical Physics 2023, 565 , 111742. https://doi.org/10.1016/j.chemphys.2022.111742
- Yi Liu, Xiaolan Yang, Khamis Masoud Khamis. Influence of Co doping concentrations and strains on the electronic structure and absorption spectrum of graphene-like ZnO monolayer. Results in Physics 2023, 44 , 106161. https://doi.org/10.1016/j.rinp.2022.106161
- Peng Wang, Xinhua Pan, Ning Wang, Sinan Zheng, Tao Zhang, Yunze Liu, Yao Wang, Fengzhi Wang, Guangmin Zhu, Jiangbo Wang, Zhizhen Ye. Epitaxy and bonding of peelable ZnO film on graphene/ZnO substrate. Journal of Alloys and Compounds 2022, 928 , 167129. https://doi.org/10.1016/j.jallcom.2022.167129
- Lei Hao, Muhammad Adnan Kamboh, Yanan Su, Lirui Wang, Shan Wang, Min Zhang, Qingbo Wang. First-principles study of electronic states, optical properties, water adsorption and dissociation properties of Pt-doped two-dimensional ZnO. Materials Science and Engineering: B 2022, 286 , 116019. https://doi.org/10.1016/j.mseb.2022.116019
- Lalmuanchhana, Bernard Lalroliana, Ramesh Chandra Tiwari, Lalhriatzuala, Ramakrishna Madaka. Transition metal decorated ZnO monolayer for CO and NO sensing: A DFT + U study with vdW correction. Applied Surface Science 2022, 604 , 154570. https://doi.org/10.1016/j.apsusc.2022.154570
- Yee Hui Robin Chang, Keat Hoe Yeoh, Junke Jiang, Heng Yen Khong, Mohd Muzamir Mahat, Soo See Chai, Fui Kiew Liew, Moi Hua Tuh. Boosting the solar conversion efficiency of MoSe
2
/PtX
2
(X = O, S) vdW heterostructure by strain and electric field engineering. Physica Scripta 2022, 97
(11)
, 115801. https://doi.org/10.1088/1402-4896/ac9561
- E. A. Peterson, T. T. Debela, G. M. Gomoro, J. B. Neaton, G. A. Asres. Electronic structure of strain-tunable Janus WSSe–ZnO heterostructures from first-principles. RSC Advances 2022, 12
(48)
, 31303-31316. https://doi.org/10.1039/D2RA05533C
- Mahsa Seyedmohammadzadeh, Cem Sevik, Oğuz Gülseren. Two-dimensional heterostructures formed by graphenelike ZnO and MgO monolayers for optoelectronic applications. Physical Review Materials 2022, 6
(10)
https://doi.org/10.1103/PhysRevMaterials.6.104004
- Zecheng Zhao, Chuanlu Yang, Zanxia Cao, Yunqiang Bian, Bingwen Li, Yunwei Wei. Two-dimensional ZnO/BlueP van der Waals heterostructure used for visible-light driven water splitting: A first-principles study. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2022, 278 , 121359. https://doi.org/10.1016/j.saa.2022.121359
- Liuqingqing Yang, Jake Heinlein, Cheng Hua, Ruixia Gao, Shu Hu, Lisa Pfefferle, Yulian He. Emerging Dual-Functional 2D transition metal oxides for carbon capture and Utilization: A review. Fuel 2022, 324 , 124706. https://doi.org/10.1016/j.fuel.2022.124706
- Kangsik Kim, Seungwoo Son, Seonwoo Lee, Jong-Hyun Ahn, Zonghoon Lee. In Situ Transmission Electron Microscopy Observation of 3C-SiC Heteroepitaxial Growth on Si Nanomembrane. Microscopy and Microanalysis 2022, 28
(S1)
, 1832-1833. https://doi.org/10.1017/S1431927622007218
- Ning Wang, Peng Wang, Fengzhi Wang, Haiping He, Jinyun Huang, Xinhua Pan, Guangming Zhu, Jiangbo Wang, Zhizhen Ye. Improved epitaxy of ZnO films by regulating the layers of graphene. Applied Surface Science 2022, 585 , 152709. https://doi.org/10.1016/j.apsusc.2022.152709
- Mariano Romero, Dominique Mombrú, Fernando Pignanelli, Ricardo Faccio, Álvaro W. Mombrú. Raman spectroscopy signatures for monomeric, dimeric and trimeric zinc dimethoxide with tetrahydrofuran adduct and early hydrolysis-condensation products on Au(111) surface: theoretical and experimental approach. Journal of Sol-Gel Science and Technology 2022, 102
(1)
, 160-171. https://doi.org/10.1007/s10971-021-05607-w
- Zhen Mou, Hongyan Zhou, Shuang Wu, Wenqi Tang, Yiyu Zhang, Kejie Zhang, Zhipin Zhou. High efficient and stable photocatalyst CeO
2
/ZnO for tetracycline degradation. Functional Materials Letters 2022, 15
(03)
https://doi.org/10.1142/S1793604722510250
- Jin Quan Ng, Qingyun Wu, L. K. Ang, Yee Sin Ang. Tunable electronic properties and band alignments of MoSi2N4/GaN and MoSi2N4/ZnO van der Waals heterostructures. Applied Physics Letters 2022, 120
(10)
https://doi.org/10.1063/5.0083736
- Lei Hao, Muhammad Adnan Kamboh, Yanan Su, Lirui Wang, Min Zhang, Jiying Zhang, Qingbo Wang. Ab initio study of the electronic, optical, and water-splitting properties of Fe-doped ZnO monolayer. Physica E: Low-dimensional Systems and Nanostructures 2022, 137 , 115059. https://doi.org/10.1016/j.physe.2021.115059
- Dong Han, Xian-Bin Li, Dan Wang, Nian-Ke Chen, Xi-Wu Fan. Doping in the two-dimensional limit:
p
/
n
-type defects in monolayer ZnO. Physical Review B 2022, 105
(2)
https://doi.org/10.1103/PhysRevB.105.024104
- Yin-Pai Lin, Boris Polyakov, Edgars Butanovs, Aleksandr A. Popov, Maksim Sokolov, Dmitry Bocharov, Sergei Piskunov. Excited States Calculations of MoS2@ZnO and WS2@ZnO Two-Dimensional Nanocomposites for Water-Splitting Applications. Energies 2022, 15
(1)
, 150. https://doi.org/10.3390/en15010150
- Rui Chen, Fuchuan Luo, Yuzi Liu, Yu Song, Yu Dong, Shan Wu, Jinhua Cao, Fuyi Yang, Alpha N’Diaye, Padraic Shafer, Yin Liu, Shuai Lou, Junwei Huang, Xiang Chen, Zixuan Fang, Qingjun Wang, Dafei Jin, Ran Cheng, Hongtao Yuan, Robert J. Birgeneau, Jie Yao. Tunable room-temperature ferromagnetism in Co-doped two-dimensional van der Waals ZnO. Nature Communications 2021, 12
(1)
https://doi.org/10.1038/s41467-021-24247-w
- K. H. Yeoh, K.-H. Chew, T. L. Yoon, Y. H. R. Chang, D. S. Ong. A first-principles study of two-dimensional NbSe
2
H/g-ZnO van der Waals heterostructures as a water splitting photocatalyst. Physical Chemistry Chemical Physics 2021, 23
(42)
, 24222-24232. https://doi.org/10.1039/D1CP03565G
- Mukesh Jakhar, Ashok Kumar. Tunable photocatalytic water splitting and solar-to-hydrogen efficiency in β-PdSe
2
monolayer. Catalysis Science & Technology 2021, 11
(19)
, 6445-6454. https://doi.org/10.1039/D1CY00953B
- Jakob Thyr, Lars Österlund, Tomas Edvinsson. Polarized and non‐polarized Raman spectroscopy of ZnO crystals: Method for determination of crystal growth and crystal plane orientation for nanomaterials. Journal of Raman Spectroscopy 2021, 52
(8)
, 1395-1405. https://doi.org/10.1002/jrs.6148
- J. R. M. Monteiro, Cicero Mota, M. S. S. Gusmão, Angsula Ghosh, H. O. Frota. Mechanical and dynamic stability of ZnX chalcogenide (X=O, S, Se, Te) monolayers and their electronic, optical, and thermoelectric properties. Journal of Applied Physics 2021, 130
(4)
https://doi.org/10.1063/5.0053738
- Saifei Yuan, Hao Ren, Guodong Meng, Wen Zhao, Houyu Zhu, Wenyue Guo. ZnO monolayer supported single atom catalysts for efficient nitrogen electroreduction to ammonia. Applied Surface Science 2021, 555 , 149682. https://doi.org/10.1016/j.apsusc.2021.149682
- Jong Chan Yoon, Zonghoon Lee, Gyeong Hee Ryu. Atomic Arrangements of Graphene-like ZnO. Nanomaterials 2021, 11
(7)
, 1833. https://doi.org/10.3390/nano11071833
- Carlos Morales, Fernando J Urbanos, Adolfo del Campo, Dietmar Leinen, Daniel Granados, Pilar Prieto, Lucía Aballe, Michael Foerster, Leonardo Soriano. Influence of chemical and electronic inhomogeneities of graphene/copper on the growth of oxide thin films: the ZnO/graphene/copper case. Nanotechnology 2021, 32
(24)
, 245301. https://doi.org/10.1088/1361-6528/abe0e8
- S.K. Sharma, R. Gupta, G. Sharma, K. Vemula, A.R. Koirala, N.K. Kaushik, E.H. Choi, D.Y. Kim, L.P. Purohit, B.P. Singh. Photocatalytic performance of yttrium-doped CNT-ZnO nanoflowers synthesized from hydrothermal method. Materials Today Chemistry 2021, 20 , 100452. https://doi.org/10.1016/j.mtchem.2021.100452
- Pornsawan Sikam, Kaito Takahashi, Thantip Roongcharoen, Thanadol Jitwatanasirikul, Chirawat Chitpakdee, Kajornsak Faungnawakij, Supawadee Namuangruk. Effect of 3d-transition metals doped in ZnO monolayers on the CO2 electrochemical reduction to valuable products: first principles study. Applied Surface Science 2021, 550 , 149380. https://doi.org/10.1016/j.apsusc.2021.149380
- Qiang Gao, Yuting Peng, Tianxing Wang, Chenhai Shen, Congxin Xia, Juehan Yang, Zhongming Wei. Quantum Confinement Effects on Excitonic Properties in the 2D vdW quantum system: The ZnO/WSe
2
Case. Advanced Photonics Research 2021, 2
(5)
https://doi.org/10.1002/adpr.202000114
- Sharafadeen Gbadamasi, Md Mohiuddin, Vaishnavi Krishnamurthi, Rajni Verma, Muhammad Waqas Khan, Saurabh Pathak, Kourosh Kalantar-Zadeh, Nasir Mahmood. Interface chemistry of two-dimensional heterostructures – fundamentals to applications. Chemical Society Reviews 2021, 50
(7)
, 4684-4729. https://doi.org/10.1039/D0CS01070G
- Jiang Zeng, Ming Lu, Haiwen Liu, Hua Jiang, X.C. Xie. Realistic flat-band model based on degenerate p-orbitals in two-dimensional ionic materials. Science Bulletin 2021, 66
(8)
, 765-770. https://doi.org/10.1016/j.scib.2021.01.006
- J.R.M. Monteiro, H.O. Frota. Graphene on a hexagonal lattice substrate with on-site Hubbard interaction. Solid State Communications 2021, 328 , 114250. https://doi.org/10.1016/j.ssc.2021.114250
- Sapna Sinha, Jamie H. Warner. Recent Progress in Using Graphene as an Ultrathin Transparent Support for Transmission Electron Microscopy. Small Structures 2021, 2
(4)
https://doi.org/10.1002/sstr.202000049
- Bakhtiar Ul Haq, S. AlFaify, Tahani A. Alrebdi, R. Ahmed, Samah Al-Qaisi, M.F. M. Taib, Gul Naz, Sarwat Zahra. Investigations of optoelectronic properties of novel ZnO monolayers: A first-principles study. Materials Science and Engineering: B 2021, 265 , 115043. https://doi.org/10.1016/j.mseb.2021.115043
- Faramarz Hossein‐Babaei, Ehsan Yousefiazari, Milad Ghalamboran. Pressure Sensitivity of Charge Conduction Through the Interface Between a Metal Oxide Nanocrystallite and Graphene. Advanced Materials Interfaces 2021, 8
(6)
https://doi.org/10.1002/admi.202001815
- Bakhtiar Ul Haq, S. AlFaify, R. Ahmed. First-principles investigations of optoelectronic properties of ZnO$$\left( {11\overline{2}0} \right)$$ and ZnO(0001) monolayers. The European Physical Journal Plus 2021, 136
(2)
https://doi.org/10.1140/epjp/s13360-021-01197-2
- Bakhtiar Ul Haq, S. AlFaify, Thamraa Alshahrani, R. Ahmed, Q. Mahmood, D.M. Hoat, S.A. Tahir. Investigations of thermoelectric properties of ZnO monolayers from the first-principles approach. Physica E: Low-dimensional Systems and Nanostructures 2021, 126 , 114444. https://doi.org/10.1016/j.physe.2020.114444
- Konstantin V. Larionov, Pavel B. Sorokin. Investigation of atomically thin films: state of the art. Uspekhi Fizicheskih Nauk 2021, 191
(01)
, 30-51. https://doi.org/10.3367/UFNr.2020.03.038745
- Hui XIANG, Hui QUAN, Yiyuan HU, Weiqian ZHAO, Bo XU, Jiang YIN. Piezoelectricity of Graphene-like Monolayer ZnO and GaN. Journal of Inorganic Materials 2021, 36
(5)
, 492. https://doi.org/10.15541/jim20200346
- K V Larionov, P B Sorokin. Investigation of atomically thin films: state of the art. Physics-Uspekhi 2021, 64
(1)
, 28-47. https://doi.org/10.3367/UFNe.2020.03.038745
- Bakhtiar Ul Haq, S. AlFaify, Thamraa Alshahrani, R. Ahmed, S.A. Tahir, Nouman Amjed, A. Laref. Exploring optoelectronic properties of ZnO monolayers originated from NaCl- and GeP-like polymorphs: A first-principles study. Results in Physics 2020, 19 , 103367. https://doi.org/10.1016/j.rinp.2020.103367
- Yilimiranmu Rouzhahong, Mariyemu Wushuer, Mamatrishat Mamat, Qing Wang, Qian Wang. First Principles Calculation for Photocatalytic Activity of GaAs Monolayer. Scientific Reports 2020, 10
(1)
https://doi.org/10.1038/s41598-020-66575-9
- Le Lin, Zhenhua Zeng, Qiang Fu, Xinhe Bao. Strain and support effects on phase transition and surface reactivity of ultrathin ZnO films: DFT insights. AIP Advances 2020, 10
(12)
https://doi.org/10.1063/5.0030624
- Asiye Shokri, Ahmad Yazdani, Kourosh Rahimi. Tunable electronic and optical properties of g-ZnO/α-PtO2 van der Waals heterostructure: A density functional theory study. Materials Chemistry and Physics 2020, 255 , 123617. https://doi.org/10.1016/j.matchemphys.2020.123617
- Bakhtiar Ul Haq, S. AlFaify, Thamraa Alshahrani, R. Ahmed, Faheem K. Butt, Sajid Ur Rehman, Zeeshan Tariq. Devising square- and hexagonal-shaped monolayers of ZnO for nanoscale electronic and optoelectronic applications. Solar Energy 2020, 211 , 920-927. https://doi.org/10.1016/j.solener.2020.09.075
- Lifen Wang, Lei Liu, Ji Chen, Ali Mohsin, Jung Hwan Yum, Todd W. Hudnall, Christopher W. Bielawski, Tijana Rajh, Xuedong Bai, Shang‐Peng Gao, Gong Gu. Synthesis of Honeycomb‐Structured Beryllium Oxide via Graphene Liquid Cells. Angewandte Chemie 2020, 132
(36)
, 15864-15870. https://doi.org/10.1002/ange.202007244
- Lifen Wang, Lei Liu, Ji Chen, Ali Mohsin, Jung Hwan Yum, Todd W. Hudnall, Christopher W. Bielawski, Tijana Rajh, Xuedong Bai, Shang‐Peng Gao, Gong Gu. Synthesis of Honeycomb‐Structured Beryllium Oxide via Graphene Liquid Cells. Angewandte Chemie International Edition 2020, 59
(36)
, 15734-15740. https://doi.org/10.1002/anie.202007244
- Kenan Elibol, Clemens Mangler, Tushar Gupta, Georg Zagler, Dominik Eder, Jannik C. Meyer, Jani Kotakoski, Bernhard C. Bayer. Process Pathway Controlled Evolution of Phase and Van‐der‐Waals Epitaxy in In/In
2
O
3
on Graphene Heterostructures. Advanced Functional Materials 2020, 30
(34)
https://doi.org/10.1002/adfm.202003300
- Xin Yin, Yizhan Wang, Tzu‐hsuan Chang, Pei Zhang, Jun Li, Panpan Xue, Yin Long, J. Leon Shohet, Paul M. Voyles, Zhenqiang Ma, Xudong Wang. Memristive Behavior Enabled by Amorphous–Crystalline 2D Oxide Heterostructure. Advanced Materials 2020, 32
(22)
https://doi.org/10.1002/adma.202000801
- Miguel Angel Gomez-Alvarez, Carlos Morales, Javier Méndez, Adolfo del Campo, Fernando J. Urbanos, Aarón Díaz, Luis Reséndiz, Jan Ingo Flege, Daniel Granados, Leonardo Soriano. A Comparative Study of the ZnO Growth on Graphene and Graphene Oxide: The Role of the Initial Oxidation State of Carbon. C 2020, 6
(2)
, 41. https://doi.org/10.3390/c6020041
- Carlos Morales, Fernando J. Urbanos, Adolfo del Campo, Dietmar Leinen, Daniel Granados, Miguel Angel Rodríguez, Leonardo Soriano. Electronic Decoupling of Graphene from Copper Induced by Deposition of ZnO: A Complex Substrate/Graphene/Deposit/Environment Interaction. Advanced Materials Interfaces 2020, 7
(10)
https://doi.org/10.1002/admi.201902062
- Ze-Cheng Zhao, Chuan-Lu Yang, Qing-Tian Meng, Mei-Shan Wang, Xiao-Guang Ma. ZnCdO2 monolayer — A complex 2D structure of ZnO and CdO monolayers for photocatalytic water splitting driven by visible-light. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2020, 230 , 118068. https://doi.org/10.1016/j.saa.2020.118068
- Yongfeng Qu, Jijun Ding, Haiwei Fu, Jianhong Peng, Haixia Chen. Adsorption of CO, NO, and NH3 on ZnO monolayer decorated with noble metal (Ag, Au). Applied Surface Science 2020, 508 , 145202. https://doi.org/10.1016/j.apsusc.2019.145202
- I Bouziani, M Kibbou, Z Haman, Y Benhouria, I Essaoudi, A Ainane, R Ahuja. Electronic and optical properties of ZnO nanosheet doped and codoped with Be and/or Mg for ultraviolet optoelectronic technologies: density functional calculations. Physica Scripta 2020, 95
(1)
, 015804. https://doi.org/10.1088/1402-4896/ab461a
- T Journot, H Okuno, N Mollard, A Michon, R Dagher, P Gergaud, J Dijon, A V Kolobov, B Hyot. Remote epitaxy using graphene enables growth of stress-free GaN. Nanotechnology 2019, 30
(50)
, 505603. https://doi.org/10.1088/1361-6528/ab4501
- Ying-Feng He, Mei-Ling Li, San-Jie Liu, Hui-Yun Wei, Huan-Yu Ye, Yi-Meng Song, Peng Qiu, Yun-Lai An, Ming-Zeng Peng, Xin-He Zheng. Growth of Gallium Nitride Films on Multilayer Graphene Template Using Plasma-Enhanced Atomic Layer Deposition. Acta Metallurgica Sinica (English Letters) 2019, 32
(12)
, 1530-1536. https://doi.org/10.1007/s40195-019-00938-8
- Xiaobao Li, Xiang Wu, Zhenyu Zhu, Guangming Li, Changwen Mi. On the elasticity and piezoelectricity of black(blue) phosphorus/ZnO van der Waals heterostructures. Computational Materials Science 2019, 169 , 109134. https://doi.org/10.1016/j.commatsci.2019.109134
Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.
Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.
The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.
Recommended Articles
Abstract
Figure 1
Figure 1. ZnO monolayer on pristine and UV/ozone-treated graphene. (a) Atomic resolution image of ZnO nanoclusters on pristine graphene. The inset in the upper right corner shows the Fourier transform of the image. (b) Atomic resolution image of ZnO nucleation on a graphene substrate after 180 s of UV/ozone treatment. The inset in the upper right corner shows the Fourier transform of the image. (c) Raman spectra of UV/ozone-treated graphene after different treatment times. (d) XPS spectra of the UV/ozone-treated graphene after different treatment times. (e) Current–gate voltage curves of the graphene for different UV/ozone treatment times. The inset in the upper corner shows the contact angle to the graphene substrate treated to UV/ozone from 0 to 180 s. (f) Mobility-carrier concentration curves of the graphene for varying UV/ozone treatment time. The scale bar is 2 nm.
Figure 2
Figure 2. Time-elapsed ARTEM images showing ZnO monolayer growth behavior under electron beam irradiation. (a) ZnO monomer is adsorbed onto the graphene substrate. (b) ZnO becomes amorphous. (c) ZnO forms clusters; unstable clusters are desorbed. (d) The ZnO cluster has periodic atomic arrangement for epitaxial growth on graphene. The scale bar is 1 nm.
Figure 3
Figure 3. Heteroepitaxial relationship of the ZnO monolayer on graphene analyzed through aberration-corrected TEM. (a) Atomic resolution image of ZnO misoriented by 30° on graphene. The inset in the upper right corner shows the Fourier transform of the image. (b) Atomic resolution image of ZnO misoriented by 0°. The inset in the upper right corner shows the Fourier transform of the image. Triangular moiré patterns are repeatedly observed every 2 nm. (c) Histogram of misorientation angles of ZnO on graphene and adhesion energy of oxygen-terminated triangular ZnO nanocluster on graphene surface vs the misorientation angle. (d) Raw image of part a. (e) Image simulation result of the ZnO monolayer on graphene. (f) Normalized intensity profiles acquired from the image simulation (black line) and experimental image (red line), corresponding to marked profiles in red dashed lines in parts d and e. The scale bars indicate 1 nm.
Figure 4
Figure 4. Lateral growth of the ZnO monolayer along the zigzag edges. (a) Time-elapsed ARTEM images show the adsorbed ZnO adatoms on graphene. Additional details can be seen in Movie S1. (b) Relative formation energy (i.e., ΔEf = Ef_growth step – Ef_initial) of the lateral growth of the ZnO monolayer with oxygen- and zinc-terminated zigzag edges and armchair edge. The red and blue spheres represent oxygen and zinc atoms, respectively, and the gray-stick honeycomb network represents graphene. (c) Raw image of part a at final step 7. (d) Intensity profile acquired from the experimental image (red line). (e) Image simulation of part a at final step 7. (f) Intensity profile acquired from the image simulation (blue line). The scale bar is 1 nm.
Figure 5
Figure 5. Electronic and optical properties of ZnO deposited with different ALD cycles on UV/ozone treated graphene. (a) STEM-EELS spectra of ZnO deposited with different ALD cycles on UV/ozone-treated graphene. The extrapolation lines (dashed lines) indicate the band gap (Eg) values 4.0, 3.71, and 3.25 eV. Each curve is scaled differently. (b) Optical transmittance measurement of ZnO deposited with different ALD cycles on graphene. (c–e) Bright-field images of suspended UV/ozone-treated graphene after 10, 20, and 200 cycles of ZnO ALD growth. The scale bar is 200 nm. (f–h) ARTEM images of 10, 20, and 200 cycles of ZnO ALD growth on the UV/ozone-treated graphene substrate. The insets in the upper right corner show the electron diffraction patterns of the imaging regions (f–h). The scale bar is 1 nm.
References
This article references 47 other publications.
- 1Choi, D.; Choi, M. Y.; Choi, W. M.; Shin, H. J.; Park, H. K.; Seo, J. S.; Park, J.; Yoon, S. M.; Chae, S. J.; Lee, Y. H.; Kim, S. W.; Choi, J. Y.; Lee, S. Y.; Kim, J. M. Adv. Mater. 2010, 22, 2187– 2192 DOI: 10.1002/adma.200903815There is no corresponding record for this reference.
- 2Chung, K.; Lee, C. H.; Yi, G. C. Science 2010, 330, 655– 657 DOI: 10.1126/science.1195403There is no corresponding record for this reference.
- 3Lee, C. H.; Kim, Y. J.; Hong, Y. J.; Jeon, S. R.; Bae, S.; Hong, B. H.; Yi, G. C. Adv. Mater. 2011, 23, 4614– 4619 DOI: 10.1002/adma.201102407There is no corresponding record for this reference.
- 4Carcia, P. F.; McLean, R. S.; Reilly, M. H.; Nunes, G. Appl. Phys. Lett. 2003, 82, 1117– 1119 DOI: 10.1063/1.1553997There is no corresponding record for this reference.
- 5Pearton, S. J.; Norton, D. P.; Ip, K.; Heo, Y. W.; Steiner, T. Superlattices Microstruct. 2003, 34, 3– 32 DOI: 10.1016/S0749-6036(03)00093-45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXkt1Kisbs%253D&md5=fe9dfd1e40835dfa9affb594fee6e54eRecent progress in processing and properties of ZnOPearton, S. J.; Norton, D. P.; Ip, K.; Heo, Y. W.; Steiner, T.Superlattices and Microstructures (2003), 34 (1-2), 3-32CODEN: SUMIEK; ISSN:0749-6036. (Elsevier Science B.V.)A review. ZnO is attracting considerable attention for its possible application to UV light emitters, spin functional devices, gas sensors, transparent electronics and surface acoustic wave devices. There is also interest in integrating ZnO with other wide bandgap ceramic semiconductors such as the AlInGaN system. In this paper we summarize recent progress in doping control, materials processing methods such as dry etching and ohmic and Schottky contact formation, new understanding of the role of hydrogen and finally the prospects for control of ferromagnetism in transition metal-doped ZnO.
- 6Nomura, K.; Ohta, H.; Ueda, K.; Kamiya, T.; Hirano, M.; Hosono, H. Science 2003, 300, 1269– 1272 DOI: 10.1126/science.1083212There is no corresponding record for this reference.
- 7Wang, Z. L. J. Phys.: Condens. Matter 2004, 16, R829– R858 DOI: 10.1088/0953-8984/16/25/R017https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXmtVyhtLY%253D&md5=333d82c73e4a8bde059791cf54e03bb7Zinc oxide nanostructures: Growth, properties and applicationsWang, Zhong LinJournal of Physics: Condensed Matter (2004), 16 (25), R829-R858CODEN: JCOMEL; ISSN:0953-8984. (Institute of Physics Publishing)A review. Zinc oxide is a unique material that exhibits semiconducting and piezoelec. dual properties. Using a solid-vapor phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobelts, nanowires and nanocages of ZnO were synthesized under specific growth conditions. These unique nanostructures unambiguously demonstrate that ZnO probably has the richest family of nanostructures among all materials, both in structures and in properties. The nanostructures could have novel applications in optoelectronics, sensors, transducers and biomedical sciences. This article reviews the various nanostructures of ZnO grown by the solid-vapor phase technique and their corresponding growth mechanisms. The application of ZnO nanobelts as nanosensors, nanocantilevers, field effect transistors and nanoresonators is demonstrated.
- 8Freeman, C. L.; Claeyssens, F.; Allan, N. L.; Harding, J. H. Phys. Rev. Lett. 2006, 96, 066102 DOI: 10.1103/PhysRevLett.96.066102There is no corresponding record for this reference.
- 9Tu, Z. C.; Hu, X. Phys. Rev. B: Condens. Matter Mater. Phys. 2006, 74, 035434 DOI: 10.1103/PhysRevB.74.035434There is no corresponding record for this reference.
- 10Tusche, C.; Meyerheim, H. L.; Kirschner, J. Phys. Rev. Lett. 2007, 99, 026102 DOI: 10.1103/PhysRevLett.99.026102There is no corresponding record for this reference.
- 11Quang, H. T.; Bachmatiuk, A.; Dianat, A.; Ortmann, F.; Zhao, J.; Warner, J. H.; Eckert, J.; Cunniberti, G.; Rummeli, M. H. ACS Nano 2015, 9, 11408– 11413 DOI: 10.1021/acsnano.5b05481There is no corresponding record for this reference.
- 12Lee, J.; Sorescu, D. C.; Deng, X. J. Phys. Chem. Lett. 2016, 7, 1335– 1340 DOI: 10.1021/acs.jpclett.6b0043212https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xlt1Sksro%253D&md5=21821a872f128003d83c7865369e5d3bTunable Lattice Constant and Band Gap of Single- and Few-Layer ZnOLee, Junseok; Sorescu, Dan C.; Deng, XingyiJournal of Physical Chemistry Letters (2016), 7 (7), 1335-1340CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)Single and few-layer ZnO(0001) (ZnO(nL), n = 1-4) grown on Au(111) were characterized via scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and d. functional theory (DFT) calcns. The in-plane lattice consts. of the ZnO(nL, n ≤ 3) are expanded compared to that of the bulk wurtzite ZnO(0001). The lattice const. reaches a max. expansion of 3% in the ZnO(2L) and decreases to the bulk wurtzite ZnO value in the ZnO(4L). The band gap decreases monotonically with increasing no. of ZnO layers from 4.48 eV (ZnO(1L)) to 3.42 eV (ZnO(4L)). Probably a transition from a planar to the bulk-like ZnO structure occurs around the thickness of ZnO(4L). Also the lattice const. and the band gap in ultrathin ZnO can be tuned by controlling the no. of layers, providing a basis for further study of this material.
- 13Demel, J.; Pleštil, J.; Bezdička, P.; Janda, P.; Klementová, M.; Lang, K. J. Phys. Chem. C 2011, 115, 24702– 24706 DOI: 10.1021/jp209973tThere is no corresponding record for this reference.
- 14Kim, Y. J.; Lee, J. H.; Yi, G. C. Appl. Phys. Lett. 2009, 95, 213101 DOI: 10.1063/1.3266836There is no corresponding record for this reference.
- 15Akhavan, O. ACS Nano 2010, 4, 4174– 4180 DOI: 10.1021/nn1007429There is no corresponding record for this reference.
- 16Kim, Y. J.; Hadiyawarman; Yoon, A.; Kim, M.; Yi, G. C.; Liu, C. Nanotechnology 2011, 22, 245603 DOI: 10.1088/0957-4484/22/24/245603There is no corresponding record for this reference.
- 17Yin, Z.; Wu, S.; Zhou, X.; Huang, X.; Zhang, Q.; Boey, F.; Zhang, H. Small 2010, 6, 307– 312 DOI: 10.1002/smll.200901968There is no corresponding record for this reference.
- 18Wu, S. X.; Yin, Z. Y.; He, Q. Y.; Huang, X. A.; Zhou, X. Z.; Zhang, H. J. Phys. Chem. C 2010, 114, 11816– 11821 DOI: 10.1021/jp103696uThere is no corresponding record for this reference.
- 19Xu, C.; Lee, J.-H.; Lee, J.-C.; Kim, B.-S.; Hwang, S. W.; Whang, D. CrystEngComm 2011, 13, 6036– 6039 DOI: 10.1039/c1ce05695fThere is no corresponding record for this reference.
- 20Viswanatha, R.; Sapra, S.; Satpati, B.; Satyam, P. V.; Dev, B. N.; Sarma, D. D. J. Mater. Chem. 2004, 14, 661– 668 DOI: 10.1039/b310404dThere is no corresponding record for this reference.
- 21Kukreja, L. M.; Misra, P.; Fallert, J.; Sartor, J.; Kalt, H.; Klingshirn, C. Ieee 2008, 61– 66 DOI: 10.1109/IPGC.2008.4781315There is no corresponding record for this reference.
- 22Saito, R.; Fujita, M.; Dresselhaus, G.; Dresselhaus, M. S. Appl. Phys. Lett. 1992, 60, 2204– 2206 DOI: 10.1063/1.10708022https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK38XktFCmtbk%253D&md5=5a9f5a777141c128585471c4b16e7a34Electronic structure of chiral graphene tubulesSaito, R.; Fujita, M.; Dresselhaus, G.; Dresselhaus, M. S.Applied Physics Letters (1992), 60 (18), 2204-6CODEN: APPLAB; ISSN:0003-6951.The electronic structure for graphene monolayer tubules is predicted as a function of the diam. and helicity of the constituent graphene tubules. The calcd. results show that approx. 1/3 of these tubules are a one-dimensional metal which is stable against a Peierls distortion, and the other 2/3 are one-dimensional semiconductors. The implications of these results are discussed.
- 23Geim, A. K.; Novoselov, K. S. Nat. Mater. 2007, 6, 183– 191 DOI: 10.1038/nmat184923https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXit1Khtrg%253D&md5=c2c02ce70a1725e6c559c173156568c5The rise of grapheneGeim, A. K.; Novoselov, K. S.Nature Materials (2007), 6 (3), 183-191CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)A review. Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when com. products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top expts. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.
- 24Castro Neto, A. H.; Guinea, F.; Peres, N. M. R.; Novoselov, K. S.; Geim, A. K. Rev. Mod. Phys. 2009, 81, 109– 162 DOI: 10.1103/RevModPhys.81.10924https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXksVamsLY%253D&md5=d4b07bf6507d26df9b0447a25131bf18The electronic properties of grapheneCastro Neto, A. H.; Guinea, F.; Peres, N. M. R.; Novoselov, K. S.; Geim, A. K.Reviews of Modern Physics (2009), 81 (1), 109-162CODEN: RMPHAT; ISSN:0034-6861. (American Physical Society)A review. This article reviews the basic theor. aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations. The Dirac electrons can be controlled by application of external elec. and magnetic fields, or by altering sample geometry and/or topol. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and no. of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the phys. properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron-electron and electron-phonon interactions in single layer and multilayer graphene are also presented.
- 25Bolotin, K. I.; Sikes, K. J.; Jiang, Z.; Klima, M.; Fudenberg, G.; Hone, J.; Kim, P.; Stormer, H. L. Solid State Commun. 2008, 146, 351– 355 DOI: 10.1016/j.ssc.2008.02.02425https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXls12qu7s%253D&md5=eb2106037936ae4e92f258596283c0c0Ultrahigh electron mobility in suspended grapheneBolotin, K. I.; Sikes, K. J.; Jiang, Z.; Klima, M.; Fudenberg, G.; Hone, J.; Kim, P.; Stormer, H. L.Solid State Communications (2008), 146 (9-10), 351-355CODEN: SSCOA4; ISSN:0038-1098. (Elsevier Ltd.)We have achieved mobilities in excess of 200,000 cm2 V -1 s-1 at electron densities of ∼2 × 1011 cm-2 by suspending single layer graphene. Suspension ∼150 nm above a Si/SiO2 gate electrode and elec. contacts to the graphene was achieved by a combination of electron beam lithog. and etching. The specimens were cleaned in situ by employing current-induced heating, directly resulting in a significant improvement of elec. transport. Concomitant with large mobility enhancement, the widths of the characteristic Dirac peaks are reduced by a factor of 10 compared to traditional, nonsuspended devices. This advance should allow for accessing the intrinsic transport properties of graphene.
- 26Wang, F.; Zhang, Y. B.; Tian, C. S.; Girit, C.; Zettl, A.; Crommie, M.; Shen, Y. R. Science 2008, 320, 206– 209 DOI: 10.1126/science.115279326https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXktlGjt7k%253D&md5=770b5df8c29893a3a42a776ebadec5dbGate-variable optical transitions in grapheneWang, Feng; Zhang, Yuanbo; Tian, Chuanshan; Girit, Caglar; Zettl, Alex; Crommie, Michael; Shen, Y. RonScience (Washington, DC, United States) (2008), 320 (5873), 206-209CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Two-dimensional graphene monolayers and bilayers exhibit fascinating elec. transport behaviors. Using IR spectroscopy, we find that they also have strong interband transitions and that their optical transitions can be substantially modified through elec. gating, much like elec. transport in field-effect transistors. This gate dependence of interband transitions adds a valuable dimension for optically probing graphene band structure. For a graphene monolayer, it yields directly the linear band dispersion of Dirac fermions, whereas in a bilayer, it reveals a dominating van Hove singularity arising from interlayer coupling. The strong and layer-dependent optical transitions of graphene and the tunability by simple elec. gating hold promise for new applications in IR optics and optoelectronics.
- 27Gokus, T.; Nair, R. R.; Bonetti, A.; Bohmler, M.; Lombardo, A.; Novoselov, K. S.; Geim, A. K.; Ferrari, A. C.; Hartschuh, A. ACS Nano 2009, 3, 3963– 3968 DOI: 10.1021/nn901275327https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsVClurfE&md5=83c292793381972d9f1e7e96b4c7b855Making Graphene Luminescent by Oxygen Plasma TreatmentGokus, T.; Nair, R. R.; Bonetti, A.; Bohmler, M.; Lombardo, A.; Novoselov, K. S.; Geim, A. K.; Ferrari, A. C.; Hartschuh, A.ACS Nano (2009), 3 (12), 3963-3968CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Strong photoluminescence (PL) can be induced in single-layer graphene using an O plasma treatment. The PL is spatially uniform across the flakes and connected to elastic scattering spectra distinctly different from those of gapless pristine graphene. O plasma can be used to selectively convert the topmost layer when multilayer samples are treated.
- 28Shin, Y. J.; Wang, Y.; Huang, H.; Kalon, G.; Wee, A. T. S.; Shen, Z.; Bhatia, C. S.; Yang, H. Langmuir 2010, 26, 3798– 3802 DOI: 10.1021/la100231uThere is no corresponding record for this reference.
- 29Lee, B.; Park, S.-Y.; Kim, H.-C.; Cho, K.; Vogel, E. M.; Kim, M. J.; Wallace, R. M.; Kim, J. Appl. Phys. Lett. 2008, 92, 203102 DOI: 10.1063/1.2928228There is no corresponding record for this reference.
- 30Leconte, N.; Moser, J.; Ordejon, P.; Tao, H. H.; Lherbier, A.; Bachtold, A.; Alsina, F.; Sotomayor Torres, C. M.; Charlier, J. C.; Roche, S. ACS Nano 2010, 4, 4033– 4038 DOI: 10.1021/nn100537zThere is no corresponding record for this reference.
- 31Liu, L.; Ryu, S. M.; Tomasik, M. R.; Stolyarova, E.; Jung, N.; Hybertsen, M. S.; Steigerwald, M. L.; Brus, L. E.; Flynn, G. W. Nano Lett. 2008, 8, 1965– 1970 DOI: 10.1021/nl0808684There is no corresponding record for this reference.
- 32Xu, Z.; Ao, Z.; Chu, D.; Younis, A.; Li, C. M.; Li, S. Sci. Rep. 2014, 4, 6450 DOI: 10.1038/srep0645032https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXksVyqs78%253D&md5=42cb4898614196d00262b002a4fd7c45Reversible Hydrophobic to Hydrophilic Transition in Graphene via Water Splitting Induced by UV IrradiationXu, Zhemi; Ao, Zhimin; Chu, Dewei; Younis, Adnan; Li, Chang Ming; Li, SeanScientific Reports (2014), 4 (), 6450CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Although the reversible wettability transition between hydrophobic and hydrophilic graphene under UV irradn. has been obsd., the mechanism for this phenomenon remains unclear. In this work, exptl. and theor. investigations demonstrate that the H2O mols. are split into hydrogen and hydroxyl radicals, which are then captured by the graphene surface through chem. binding in an ambient environment under UV irradn. The dissociative adsorption of H2O mols. induces the wettability transition in graphene from hydrophobic to hydrophilic. Our discovery may hold promise for the potential application of graphene in water splitting.
- 33Liu, H.; Liu, Y.; Zhu, D. J. Mater. Chem. 2011, 21, 3335– 3345 DOI: 10.1039/C0JM02922J33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXit1ymsrw%253D&md5=29b3a40cfb5efd00092e3a579dfca24fChemical doping of grapheneLiu, Hongtao; Liu, Yunqi; Zhu, DaobenJournal of Materials Chemistry (2011), 21 (10), 3335-3345CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)A review. Recently, a lot of effort has been focused on improving the performance and exploring the elec. properties of graphene. A review with 153 refs. This article presents a summary of chem. doping of graphene aimed at tuning the electronic properties of graphene. p-Type and n-type doping of graphene achieved through surface transfer doping or substitutional doping and their applications based on doping are reviewed. Chem. doping for band gap tuning in graphene is also presented. It will be beneficial to designing high performance electronic devices based on chem. doped graphene.
- 34Jiang, Q. G.; Ao, Z. M.; Chu, D. W.; Jiang, Q. J. Phys. Chem. C 2012, 116, 19321– 19326 DOI: 10.1021/jp3050466There is no corresponding record for this reference.
- 35Huh, S.; Park, J.; Kim, Y. S.; Kim, K. S.; Hong, B. H.; Nam, J. M. ACS Nano 2011, 5, 9799– 9806 DOI: 10.1021/nn204156nThere is no corresponding record for this reference.
- 36Mulyana, Y.; Uenuma, M.; Ishikawa, Y.; Uraoka, Y. J. Phys. Chem. C 2014, 118, 27372– 27381 DOI: 10.1021/jp508026gThere is no corresponding record for this reference.
- 37Wang, W.; Ruiz, I.; Lee, I.; Zaera, F.; Ozkan, M.; Ozkan, C. S. Nanoscale 2015, 7, 7045– 7050 DOI: 10.1039/C4NR06795AThere is no corresponding record for this reference.
- 38Jiang, B.; Zhang, C.; Jin, C.; Wang, H.; Chen, X.; Zhan, H.; Huang, F.; Kang, J. Cryst. Growth Des. 2012, 12, 2850– 2855 DOI: 10.1021/cg201727t38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XmvFGntbo%253D&md5=bc1ac9ed21378e267c613771ddac5942Kinetic-Dynamic Properties of Different Monomers and Two-Dimensional Homoepitaxy Growth on the Zn-Polar (0001) ZnO SurfaceJiang, Baofeng; Zhang, Chunmiao; Jin, Changlian; Wang, Huiqiong; Chen, Xiaohang; Zhan, Huahan; Huang, Feng; Kang, JunyongCrystal Growth & Design (2012), 12 (6), 2850-2855CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)Homoepitaxy ZnO monolayer growth was studied from dynamics to kinetics taking ZnO mols. and Zn-O cluster monomers into account in the atomistic growth by 1st-principles calcns. and Monte Carlo simulations and compared with exptl. growth by MBE. Theor., the ZnO mols. scatter equivalently on both the wurtzite sites (WSs) and zincblende sites (ZSs) and stick even at high temps. The Zn3O1 monomers resulted in a larger island size and a higher compact degree and the growth approached to the two-dimensional mode at high temp.; the film structure finalized in the single wurtzite phase structure with more vacancies, which agreed with the in situ scanning tunnel microscopy observation for the growth in Zn-rich conditions to form Zn3O1 monomers. For the Zn1O3 monomers, the transformation from ZSs to WSs was more difficult even with temp. increase and they could locate at both WSs and ZSs, consistent with the in situ RHEED for the growth in O-rich conditions to form Zn1O3 monomers. Combining the advantages of both cluster monomers, a two step-growth technique was developed by alternatively supplying Zn and O. The resultant ZnO films exhibited flat texture and uniform phase structure as indicated by the at. steps in the STM images and the streaky RHEED patterns.
- 39Peng, Z. A.; Peng, X. G. J. Am. Chem. Soc. 2002, 124, 3343– 3353 DOI: 10.1021/ja0173167There is no corresponding record for this reference.
- 40Kohler, U.; Dorna, V.; Jensen, C.; Kneppe, M.; Piaszenski, G.; Reshoft, K.; Wolf, C. Elsevier Science Bv 2004, 391– 412 DOI: 10.1016/B978-044451386-1/50020-9There is no corresponding record for this reference.
- 41Jo, J.; Yoo, H.; Park, S. I.; Park, J. B.; Yoon, S.; Kim, M.; Yi, G. C. Adv. Mater. 2014, 26, 2011– 2015 DOI: 10.1002/adma.201304720There is no corresponding record for this reference.
- 42Dulub, O.; Diebold, U.; Kresse, G. Phys. Rev. Lett. 2003, 90, 016102 DOI: 10.1103/PhysRevLett.90.016102There is no corresponding record for this reference.
- 43Lauritsen, J. V.; Porsgaard, S.; Rasmussen, M. K.; Jensen, M. C. R.; Bechstein, R.; Meinander, K.; Clausen, B. S.; Helveg, S.; Wahl, R.; Kresse, G.; Besenbacher, F. ACS Nano 2011, 5, 5987– 5994 DOI: 10.1021/nn2017606There is no corresponding record for this reference.
- 44Ryu, G. H.; Park, H. J.; Ryou, J.; Park, J.; Lee, J.; Kim, G.; Shin, H. S.; Bielawski, C. W.; Ruoff, R. S.; Hong, S.; Lee, Z. Nanoscale 2015, 7, 10600– 10605 DOI: 10.1039/C5NR01473EThere is no corresponding record for this reference.
- 45Rafferty, B.; Brown, L. M. Phys. Rev. B: Condens. Matter Mater. Phys. 1998, 58, 10326– 10337 DOI: 10.1103/PhysRevB.58.10326There is no corresponding record for this reference.
- 46Kim, E.; Jiang, Z. T.; No, K. Jpn. J. Appl. Phys. 2000, 39, 4820– 4825 DOI: 10.1143/JJAP.39.482046https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXmtFymsLo%253D&md5=0d347d836e7b295d4f55c8b7f4a962f0Measurement and calculation of optical band gap of chromium aluminum oxide filmsKim, Eunah; Jiang, Zhong-Tao; No, KwangsooJapanese Journal of Applied Physics, Part 1: Regular Papers, Short Notes & Review Papers (2000), 39 (8), 4820-4825CODEN: JAPNDE; ISSN:0021-4922. (Japan Society of Applied Physics)The optical band gap is a basic property of optical materials. The measured band gap depends not only on the material but also on its characteristics such as crystallinity and stoichiometry. The optical band gap of chromium aluminum oxide films was measured and calcd. by three different methods. Firstly, the conventional exptl.-graphical method is used. This method is applicable only to an all-cryst. phase or an all-amorphous phase. Secondly, an exptl.-calcn. method applicable to films composed of both cryst. and amorphous phases was used. The authors calcd. the optical band gap between the HOMO of O2p and the LUMO of Cr3d in Cr1.71Al0.29O3 films composed of both amorphous and cryst. phases. A band gap for the d-d transition was obtained. The measured value was compared with the theor. optical band gap calcd. by the discrete variational-Xα (DV-Xα) method.
- 47Kim, K.; Lee, H. B.; Johnson, R. W.; Tanskanen, J. T.; Liu, N.; Kim, M. G.; Pang, C.; Ahn, C.; Bent, S. F.; Bao, Z. Nat. Commun. 2014, 5, 4781 DOI: 10.1038/ncomms578147https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2M%252Fns1GisQ%253D%253D&md5=180112be723f8fcda3c065997157c751Selective metal deposition at graphene line defects by atomic layer depositionKim Kwanpyo; Lee Han-Bo-Ram; Johnson Richard W; Tanskanen Jukka T; Liu Nan; Bent Stacey F; Bao Zhenan; Kim Myung-Gil; Pang Changhyun; Ahn ChiyuiNature communications (2014), 5 (), 4781 ISSN:.One-dimensional defects in graphene have a strong influence on its physical properties, such as electrical charge transport and mechanical strength. With enhanced chemical reactivity, such defects may also allow us to selectively functionalize the material and systematically tune the properties of graphene. Here we demonstrate the selective deposition of metal at chemical vapour deposited graphene's line defects, notably grain boundaries, by atomic layer deposition. Atomic layer deposition allows us to deposit Pt predominantly on graphene's grain boundaries, folds and cracks due to the enhanced chemical reactivity of these line defects, which is directly confirmed by transmission electron microscopy imaging. The selective functionalization of graphene defect sites, together with the nanowire morphology of deposited Pt, yields a superior platform for sensing applications. Using Pt-graphene hybrid structures, we demonstrate high-performance hydrogen gas sensors at room temperature and show its advantages over other evaporative Pt deposition methods, in which Pt decorates the graphene surface non-selectively.
Supporting Information
Supporting Information
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.nanolett.6b03621.
Experimental methods and additional data (PDF)
Supporting Movie 1, showing time-elapsed images of adsorbed ZnO adatoms on a graphene substrate (AVI)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.