The ionization or transition energies of Ga or N vacancy in bulk GaN were investigated by density-functional based tight-binding calculations. Calculations of the formation energy of neutral configurations were in agreement with previous DFT determination. It was shown that for the defect configurations, the metallic character of Ga atoms needs to adjust the level of the valence band maximum.

Ionization Energy of GaN Point Defects. A.Béré, I.Belabbas, G.Nouet, P.Ruterana, J.Chen, G.Segda, J.Koulidiati: Physica Status Solidi C, 2007, 4[7], 2593-6