Band structures and deep levels were calculated, for both cubic and hexagonal nitride semiconductors, by using the sp3s* tight-binding formulation and the Green's function technique. An anti-bonding s-like state which was produced by a N vacancy was predicted to appear at 0.3eV below the conduction-band edge in GaN. This became shallower, and then resonant with the conduction band in InGaN, as the In content was increased.

E.Yamaguchi, M.R.Junnarkar: Journal of Crystal Growth, 1998, 189-190, 570-4