Deep ultra-violet photoluminescence spectroscopy was employed to study deep impurity transitions in AlxGa1–xN (x = 0 to 1) epilayers. Two groups of deep impurity transitions were observed, which were assigned to the recombination between shallow donors and two different deep level acceptors involving cation vacancies (Vcation) and Vcation complexes in AlxGa1–xN alloys. These acceptor levels were pinned to two different energy levels common to AlxGa1–xN alloys (x = 0 to 1). The deep impurity transitions related with Vcation complexes were observed in AlxGa1–xN alloys between x = 0 and 1, while those related with Vcation were observed only in AlxGa1–xN alloys between x = 0.58 and 1. This pointed out the fact that the formation of Vcation was more favorable in Al-rich AlGaN alloys, while Vcation complexes could be formed in the whole range of x between 0 and 1.

Deep Impurity Transitions Involving Cation Vacancies and Complexes in AlGaN Alloys. K.B.Nam, M.L.Nakarmi, J.Y.Lin, H.X.Jiang: Applied Physics Letters, 2005, 86[22], 222108 (3pp)