N-VACANCIES IN ALXGA1-XN

Predictions of deep levels associated with N vacancies in AlxGa1-xN as functions of alloy composition x explain both (i) the dramatic change from naturally n-type to semi-insulating behavior (for x = x(c) congruent-to 0.5) in terms of a shallow-deep transition for the vacancy's T2 level, and (ii) the major photoluminescence feature in terms of recombination from the vacancy's A1 deep level. Extrinisic photoluminescence data for Zn-doped AlxGa1-xN are interpreted in terms of a transition from the conduction band to a T2-symmetric deep level in the lower part of the gap. This level is associated with antisite Zn on a N site, Zn(N).