Tuning of the electronic and optical properties of AlN monolayer by fluorination: Study of many-body effects

Abstract

We have studied the electronic and optical properties of the pristine and fluorinated Aluminium nitride (AlN) monolayers using first-principles calculations based on the density functional theory (DFT), the many-body perturbation theory, and solving of Bethe-Salpeter Equation (BSE). Based on DFT-GGA (G0W0) calculations, we find that the AlN monolayer has an indirect band gap of 2.96 eV (5.7 eV). However, by fluorination of the AlN monolayer, this indirect band gap will be changed into a direct band gap of 3.41 eV (7.92 eV). Furthermore, the analysis of the optical absorption spectrum and excitonic effects such as the electron-hole interactions shows that the fluorination of the AlN monolayer will increase the binding energy of the first absorption spectrum peak from 1.72 eV to 2.1 eV. Further, the fluorination causes fluorinated AlN monolayer to be more transparent than AlN monolayer. Our results suggest that the fluorinated AlN monolayer can be a promising candidate for the manufacture of optoelectronic devices in the ultraviolet region.