Monolayer C2/m−SnX ( X=P , As): An in-plane anisotropic two-dimensional direct band gap semiconductor with ultrahigh mobility, ideal IR-VIS light transparency, and high absorbance

Abstract

Over the years, designing and establishing new materials with good stability, a suitable band gap, and high carrier mobility have become the focus in researching two-dimensional (2D) materials. In this paper, we predict two 2D semiconductors, $C2/m\text{\ensuremath{-}}\mathrm{Sn}X$ ($X=\text{P}$, As), using first-principles simulation. They possess excellent dynamical and thermal stability, low structural symmetry, high cohesive energy, and good flexibility for the structural properties. Regarding electronic properties, SnP and SnAs are direct band gap semiconductors with suitable band gap values. In addition, they exhibit a high carrier mobility (about $\ensuremath{\sim}{10}^{3}\text{--}{10}^{4}\phantom{\rule{4.pt}{0ex}}{\text{cm}}^{2}\phantom{\rule{0.16em}{0ex}}{\text{V}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\text{s}}^{\ensuremath{-}1}$). Their optical properties reveal good transparency in the infrared and visible light regions, but the primary response region of light locates in the ultraviolet area. In addition, their electronic and optical properties show different characteristics in different directions. Therefore, $C2/m\text{\ensuremath{-}}\mathrm{Sn}X$ ($X=\text{P}$, As) are 2D direct band gap semiconductors with excellent stability, a suitable band gap value, high carrier mobility, and good IR-VIS light transparency. We suggest that the group IV-V 2D semiconductor $C2/m\text{\ensuremath{-}}\mathrm{Sn}X$ ($X=\text{P}$, As) will have bright prospects in field-effect transistors, integrated circuits, the hole transport layer of solar cells, blue LEDs, and other nanoelectronic and nano-optoelectronic devices.