Band structure engineering in gallium sulfide nanostructures

The gallium sulfide monolayer is demonstrated as a promising two-dimensional semiconductor material with considerable properties. The present work, investigates the bandgap modulation of GaS monolayer under biaxial or uniaxial strain, using density functional theory calculation. We find that GaS monolayer shows an indirect bandgap that limits its optical applications. The uniaxial strain shifts bandgap from indirect to direct in gallium sulfide monolayer at the strain of ε = − 10 percent along y direction. Also, by analyzing Poisson’s ratio, we figure out that Gallium Sulfide monolayer has isotropic mechanical nature under pressure. The detailed reasons for the bandgap modulation are discussed by analyzing the projected density of states. Besides, we investigate indirect to direct bandgap shifts on Gallium Sulfide nanoribbons through varying nanoribbon width as well as edge hydrogen passivations. The direct bandgap accompanied by the isotropic mechanical feature in the Gallium Sulfide monolayer, facilitates and moves up its practical application.