Electronic structure of novel GaS/GaSe heterostructures based on GaS and GaSe monolayers

In this study, we investigate the electronic and structural and properties of GaS/GaSe heterostructures and GaS/GaSe crystals built by simultaneously stacking of GaS and GaSe monolayers bounded by van der Waals (vdW) forces. Our calculations using vdW corrected density functional theory (DFT) confirm that the GaS/GaSe novel heterostructures transforms from an indirect to a direct band gap material for the two stackings considered in this study as well as could be produce direct band gap ranging from 1.308 to 1.78 eV, which located in the visible light region, suggesting possible optoelectronic applications. Interestingly, the GaS/GaSe heterostructures have unprecedented properties that can be promised in open possible applications such as nanodevices, photodetectors, sensors, solar cells, and valleytronic components. Generally, the direct gaps of heterostructures and crystals are smaller than that of GaS and GaSe monolayers, in addition, GaS/GaSe heterostructures have band gaps larger than those of GaS/GaSe crystals. The conduction band minimum and valence band maximum are located in the same parts of GaS/GaSe heterostructures. Most importantly, the stacking predominantly effects the valence and band conduction splitting at K, M, and Γ points. Also, the dynamical stability of these system is confirmed using the phonon curves indicate that all frequencies are positive.