First-principles calculations were used to predict the behaviour of Li. It was noted that substitutional LiGa was a double acceptor, with a first ionization energy of 0.16eV. Its use as a p-dopant was hindered by the preference of Li for interstitialcy; which led to self-compensation. Interstitial Li was predicted to diffuse freely at about 600K, and to recombine exothermically with Ga vacancies to produce LiGa. Both results closely matched experiments on implanted Li isotopes. The effects of this interstitial-substitutional transition was considered with reference to the availability of Ga vacancies for the chemical incorporation of implants, and the role of Ga interstitial donors.

Incorporation, Diffusion, and Electrical Activity of Li in GaN F.Bernardini, V.Fiorentini: Physical Review B, 2000, 61[19], 12598-601