Influence of Nanoarchitectures on Interlayer Interactions in Layered Bi–Mo–Se Heterostructures

Recently, it was shown that the metastable heterostructure (BiSe)_0.97MoSe₂, consisting of alternating bilayers of BiSe and MoSe₂ trilayers, contained both the semiconducting 2H- and the metallic 1T-polytype of MoSe₂. In this study, we investigated five other structures containing different stackings of BiSe, Bi₂Se₃, and MoSe₂ layers in the repeat unit to understand what facilitates the stabilization of metastable constituent layers. X-ray diffraction was used to characterize the stacking sequences and the structure of the different layers, and X-ray photoelectron spectroscopy and Raman spectroscopy were carried out to understand the occurring interlayer interactions. A sufficient transfer of electrons from the BiSe layers into MoSe₂ is required to form 1T-MoSe₂ upon crystallization. The yield of 1T-MoSe₂ is reduced if charges are localized at antiphase boundaries in BiSe or if filling of conduction band states in Bi₂Se₃ or 2H-MoSe₂ occurs. If the repeat unit contains more than one layer of MoSe₂, band structure changes allow charges from BiSe to be distributed over all available dichalcogenide layers, suppressing the formation of both 1T-MoSe₂ and antiphase boundaries. Understanding the interplay between the different layers may enable the design of heterostructures with the desired constituent structure and properties.