Electronic and Optical Properties of Monolayer Sb2Te3 Using Biaxial Strain

The effect of bi-axial strain on the band structure and optical properties of Monolayer Sb2Te3 were studied by using the first-principles method based on density functional theory. The band gap of Monolayer Sb2Te3 increases linearly from tensile strain to compression strain. Due to the anisotropy of strain-free Sb2Te3 monolayer, the real part of the dielectric function presents different characteristics along the x and z axes. The imaginary part of the dielectric function is highly anisotropic in the energy range of 0-6 eV, but becomes isotropic when the energy is greater than 6 eV. The intensity of optical absorption coefficient increases, and the absorption region changes from tensile strain to compressive strain at the same time. When the incident photon energy is greater than 12 eV, the reflectivity curves in both of x and z axes tend to zero under all strains.