First-Principles Study on the Structural, Electronic and Optical Properties of Janus SiSSe Monolayer

Abstract

Janus two-dimensional materials have garnered research interest in recent times due to their intriguing properties arising from out-of-plane symmetry breaking. In this work, Janus monolayer SiSSe has been theoretically predicted and characterized by first-principles numerical calculations. The material is dynamically stable as there is no negative frequency in the phonon dispersion curves. The material is found to be mechanically stable on the basis of Born's criteria. The electronic bandstructure reveals that the material possesses an indirect bandgap of 0.6501 eV. The bandgap can be tuned from 0.1003 eV to 0.9852 eV by the application of compressive and tensile biaxial strain. Moreover, at biaxial strain of −8%, the material undergoes a transition from semiconductor to metal. The optical properties of monolayer SiSSe are also investigated in this study. The absorption co-efficient has its major values within the UV region of the electromagnetic spectrum. The obtained results help to conclude that SiSSe is a promising candidate for switching applications and for devices that operate in the UV region.