Effects of vacancies on electronic and optical properties of GaN nanosheet: A density functional study

In this work, electronic and linear optical properties of GaN nanosheet are investigated through density functional theory and the dielectric tensor is derived within the random phase approximation (RPA). Electronic band structure calculations indicate that Ga atom vacancies in the 2D GaN system leads to n-type semiconductor, whereas the N atom vacancies change the electronic structure to a p-type semiconductor. Dielectric function, absorption coefficient, optical conductivity, extinction index, reflectivity, loss function and the refraction index of the GaN nanosheet and the Ga-defected or N-defected GaN systems are studied for both parallel (E∥x) and perpendicular (E∥z) applied electric field polarizations. Our results confirm that GaN nanosheet is a semiconductor which is sensitive to the type of vacancies and shows optical anisotropy at both polarizations states.