Biaxial strain and electric field effects on the electronic, optical, and photocatalytic properties of full hydrogenated SiSn monolayer

Abstract

The electronic, optical, and photocatalytic characteristics of full hydrogenated stanene-silicene monolayer H–SiSn–H were investigated under biaxial strain and external electric field via first-principles calculations. The binding energy, phonon dispersion and ab initio molecular dynamics simulations display this material's excellent ambient stability. The obtained results show that at the equilibrium, a full hydrogenated SnSi sheet is a direct semiconductor with a gap energy of 2.62 eV by GW approximation. The analysis of band edge alignment indicates that the H– SiSn –H sheet can possess photocatalytic properties for water splitting when biaxial strain or an electric field is applied. We can tune the gap energy of the full hydrogenated SiSn sheet by biaxial strain or electric field. The direct-to-indirect bandgap transition occurs at certain compression of the biaxial strain in this binary system. Comparing to the bare SnSi sheet, the complete hydrogenation causes absorption peaks of SnSi to shift towards the higher frequency region. The optical characteristics of the full hydrogenated SiSn sheet depend greatly on the strain, while the influence of the electric field on them is negligible. These results can provide beneficial information for the potential application of the H–SnSi–H sheet in nanoelectronics and photocatalytic activities.