First principles study of point defects and Li doping on the electronic structure and photovoltaic performance of single-layer GaN

The preparation of single-layer GaN by chemical vapor deposition inevitably generates H interstitials. In this study, the optical properties of single-layer Ga₃₆N₃₆, Ga₃₄LiN₃₆ and Ga₃₄H_iLiN₃₆ (0 0 1) surfaces were investigated by using the first-principles method. In the presence of Li doping and H interstitial, the dielectric function and reflectivity red-shifted in the low-energy range and the dielectric function and reflectivity of the Ga₃₆N₃₆ improved. In the visible range of the absorption spectrum, the impurity-containing surfaces red-shifted, and the light absorption on the Ga₃₆N₃₆ improved. The Ga₃₄H_iLiN₃₆ (0 0 1) surface performed better as a photovoltaic material than other surfaces.