Strain engineering and stacking pattern tune the electrical conductivity of two-dimensional SiPS

Abstract

In this work, a new two-dimensional material with excellent stability and an indirect band gap of 3.304 eV (HSE06), called SiPS, is predicted by using first-principles calculations. The electron calculations demonstrate that SiPS exhibits strong anisotropies in electron effective mass and transport ability. At room temperature (300 K), the calculated electron mobility along y direction is 172.6 cm2 V−1 s−1, which is about 108 times larger than that along x direction (1.6 cm2 V−1 s−1). Under the biaxial strain, the band gap can be tuned (2.265–3.585 eV) as well as the electron effective mass and transport ability, especially the remarkable reduction of electron effective mass and the improvement of electron mobility along x direction. In addition, in the exploration of bilayer SiPS with four stacking patterns, it can be observed that pattern III triggers the transformation of bilayer SiPS from indirect to direct band gap. The electron mobility of bilayer SiPS can be tuned by the different stacking patterns, and the results show that the electron mobility of patterns I and II are 3.3–6.2 and 375.2–440.3 cm2 V−1 s−1 along x and y direction, respectively, which are over two times higher than those of monolayer SiPS. For patterns III and IV, the electron mobility along x and y directions exhibit a small difference, with the values of 74.5–65.3 and 64.1–34.4 cm2 V−1 s−1, respectively. These advantaged results shed light on two-dimensional SiPS for promising applications in developing unidirectional or bidirectional conductive electronic devices.