Optical anisotropy and strain tunable optical, electronic and structural properties in monolayer GeP: A computational study

Abstract

This paper studies the structural, electronic and optical properties of a new group IV-V two-dimensional (2D) material GeP under the influence of different strains by using the first-principles calculations. The strains discussed in this paper include both the uniaxial strain along the different lattice vector directions, as well as the biaxial strain. The results show that monolayer GeP is a 2D dynamically stable semiconductor with low structural symmetry. In terms of the electronic property, regardless of the compressive strain or tensile strain applied in any direction, the band-gap of the monolayer GeP exhibits a decreasing tendency, and it remains semiconductivity in the range of −10% compressive strain to 10% tensile strain. As for the optical property, it is anisotropic. When GeP is subjected to a strain, regardless of the directions, the optical property of monolayer GeP is significantly affected more by tensile strain than by compressive strain. When the monolayer GeP is subjected to a tensile strain, its optical absorption and reflectivity in the visible light region to some extent increase, while its transmittance reduces. When it is subjected to a compressive strain, the main change in optical properties such as absorption and reflectivity occurs in the deep ultraviolet region. In particular, the monolayer GeP is most susceptible to deformation by the strain in a direction, and only compressive strain in a direction will cause GeP to undergo a transition from an indirect band-gap semiconductor to a direct band-gap semiconductor, which results in the improvements of absorption efficiency and reflectivity efficiency in the low energy region. Our calculated results indicate that the electronic and optical properties of monolayer GeP can be efficiently and regularly regulated by strain. In the future, it can be a suitable 2D materials used in optically polarized devices, blue light-emitting diode devices, and strain-tunable photoelectric nanodevices.