Strain-dependent optical properties of the novel monolayer group-IV dichalcogenides SiSsemiconductor: a first-principles study.

We studied the structural, electronic, and optical characters of SiS, a new type of group IV-VI two-dimensional semiconductor, in this article. We focused on monolayer SiSand its characteristic changes when different strains are applied on it. Results reveal that the monolayer SiSis dynamically stable when no strain is applied. In terms of electronic properties, it remains a semiconductor under applied strain within the range from -10% to 10%. Besides, its indirect band-gap is altered regularly after applying a strain, whereas different strains lead to various changing trends. As for its optical properties, it exhibits remarkable transparency for infrared and most visible light. Its main absorption and reflection regions lie in the blue and ultraviolet areas. The applied uniaxial strain causes its different optical properties along the armchair direction and zigzag direction. Moreover, the tensile strain could tune its optical properties more effectively than the compressive strain. When different strains are applied, the major changes are in blue and ultraviolet regions, but only minor changes can be found in infrared and visible regions. So its optical properties reveal good stability in infrared and visible regions. Therefore, SiShas a promising prospect in nano-electronic and nano-photoelectric devices.