Electronic and optical properties of advance semiconductor materials: BN, AlN and GaN nanosheets from first principles

Abstract

We investigate the electronic and linear optical properties of BN, AlN and GaN hexagonal nanosheets using the band structure results obtained through the full potential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT). The dielectric tensor and corresponding optical properties are derived within the random phase approximation (RPA). Specifically, the dielectric function, absorption coefficient, optical conductivity, extinction index, reflectivity, loss function and the refraction index of these above mentioned nanosheets are calculated for both parallel (E||x) and perpendicular (E||z) electric field polarizations. Calculated results show that the hexagonal XN (X=B, Al and Ga) nanosheets have semiconductor characters with wide band gap of about 4.96, 2.73 and 1.95eV respectively. The optical conductivity in E||x and E||z starts with a gap about 2.92eV and 6.73eV for BN, 2.73eV and 3.52eV for AlN and 1.61eV and 3.58eV for GaN, confirms that these nanosheets have semiconductor properties moreover the optical spectra are isotropic along these two polarizations. These results propose potential application for the development of BN, AlN and GaN nano structures in electronic and optoelectronic devices.