Vertical van der Waals Heterostructure of Single Layer InSe and SiGe

Abstract

We present a first-principles investigation on the stability, electronic structure and mechanical response of ultra-thin heterostructure composed of single layers of InSe and SiGe. First, by per- forming total energy optimization and phonon calculations, we show that single layers of InSe and SiGe can form dynamically stable heterostructures in 12 different stacking types. Valence and conduction band edges of the heterobilayers form a type-I heterojunction having a tiny bandgap ranging between 0.09-0.48 eV. Calculations on elastic-stiffness tensor reveal that two mechanically soft single layers form a heterostructure which is stiffer than constituent layers due to relatively strong interlayer interaction. Moreover, phonon analysis show that the bilayer heterostructure has highly Raman active modes at 205.3 and 43.7 cm −1 , stemming from out-of-plane interlayer mode and layer breathing mode, respectively. Our results show that, as a stable type-I heterojunction, ultra-thin heterobilayer of InSe/SiGe holds ...