Possible indirect to direct bandgap transition in SnS2 via nickel doping

Abstract

Direct bandgap semiconductors play a critical role in optoelectronics. In this regard, SnS2 is a two-dimensional (2D) layered semiconductor which has ignited intensive attention due to its semiconducting nature and nontoxicity. The pristine SnS2, however, has an indirect bandgap. For a more widespread use, it is highly desired to translate SnS2 into direct bandgap semiconductors by controlling external parameters. Utilizing first-principles calculation methods with HSE hybrid functional, we show the possibility of indirect to direct bandgap transition in SnS2 single layer via nickel (Ni) doping. A substitutional Ni-dopant on the tin site of SnS2 generates new band lines at the bottom of the conduction band due to strong orbital hybridization with states of its nearby sulfur atoms. Consequently, the direct bandgap can be achieved in SnS2; moreover, the bandgap size is narrowed as the number of Ni-dopants increases.