Electronic structure and optical properties of β-GaSe based on the TB-mBJ approximation

Abstract

We have calculated the electronic structure and optical properties of gallium-selenide (GaSe) layered semiconductor in the β-structural phase based on the Tran–Blaha modified Becke–Johnson (TB-mBJ) approximation. Because of the spatial separation of the valence band maxima (VBM) and conduction band minima (CBM) electronic states, using the TB-mBJ approximation, the calculated gap considerably improves and becomes comparable to the experimental values. We have also calculated the electronic structure and optical properties of the single-layer GaSe structure and a two nanometer GaSe particle. The quantum confinement effect can be clearly observed from the enhanced obtained gap of the restricted structures. The optical refraction index and absorbance are in close agreement with the experiment, though these properties are calculated within the random phase approximation (RPA). Our calculation shows the ability of TB-mBJ and RPA in producing the optical properties of this semiconductor family in bulk and nano-size structures.