A Raman spectroscopic study was made of the behavior of O and Si donors under a hydrostatic pressure. The ground state of O was found to transfer from a shallow level to a deep-gap state at pressures above 20GPa; thus recalling the behavior of DX centers in GaAs. It was predicted that O would introduce a deep gap state in AlxGa1-xN, when x was greater than 0.40. No such state was introduced into Si-doped material at pressures of up to at least 25GPa. This was attributed to a difference in the lattice sites of the dopants.

C.Wetzel, T.Suski, J.W.Ager, E.R.Weber, E.E.Haller, S.Fischer, B.K.Meyer, R.J.Molnar, P.Perlin: Physical Review Letters, 1997, 78[20], 3923-6