Electronic, transport and optical properties of monolayer $\alpha$ and $\beta -$GeSe: A first-principles study

Abstract

The extraordinary properties and the novel applications of black phosphorene induce the research interest on the monolayer group-IV monochalcogenides. Here using the first-principles calculations, we systematically investigate the electronic, transport and optical properties of monolayer $\alpha -$ and $\beta -$GeSe, the latter of which was recently experimentally realized. We found that, monolayer $\alpha -$GeSe is a semiconductor with direct band gap of 1.6 eV, and $\beta -$GeSe displays indirect semiconductor with the gap of 2.47 eV, respectively. For monolayer $\beta -$GeSe, the electronic/hole transport is anisotropic with an extremely high electron mobility of 7.84 $\times 10^4$$c{m}^2/V\cdot s$ along the zigzag direction, comparable to that of black phosphorene. Furthermore, for $\beta -$GeSe, robust band gaps nearly disregarding the applied tensile strain along the zigzag direction is observed. Both monolayer $\alpha -$ and $\beta -$GeSe exhibit anisotropic optical absorption in the visible spectrum.

17 pages, 5 figures