First-principles studies of electronic structure and optical properties of GaN surface doped with Si

The electronic structure of wurtzite GaN doped with Si was calculated using the first-principles plane-wave pseudopotential method, based on the density function theory. The results show that GaN doped with Si is n-type semiconductor with direct band-gap, band gap increases, compared with that of undoped GaN. The doped system was sectioned in (0 0 0 1) and (0 0 0 1¯) direction. (0 0 0 1¯) surface has larger change in morphology than (0 0 0 1) surface, and is against the escape of electrons. The electronic non-locality of (0 0 0 1) surface is enhanced. The electronic structure and optical properties of GaN(0 0 0 1) surface with Si doping were analyzed and compared with those of undoped surface. The studies show that the absorption to visible light enhances, absorption to ultraviolet light abates. Doped surface is fit for ultraviolet detection.