First principles study of single-layer SnSe2 under biaxial strain and electric field: Modulation of electronic properties

In this study, we investigate systematically the effect of strain engineering and electric field on electronic properties of single-layer SnSe2 using density functional theory. Our calculated results indicate that the single-layer SnSe2 is a semiconductor with a small band gap of 0.715 eV at the equilibrium state. The electronic states near the Fermi level are mainly contributed by Sn-d and Se-p orbitals, especially the contribution of the Se-p orbital to the valence band is dominant. Under biaxial strain, the band gap of the single-layer SnSe2 changes abnormally. While compressive biaxial strain reduces band gap rapidly, the band gap of the single-layer SnSe2 only increases slightly when increasing the tensile biaxial strain. In contrast to the strain-dependence case, the influence of the external electric field on the electronic properties of the single-layer SnSe2 is quite small and the energy gap of the single-layer SnSe2 does not depend on the direction of the perpendicular electric field. Our calculated results can provide more information for application possibility of the single-layer SnSe2 in nanoelectronic devices.