Passivation of the beryllium acceptor in GaN and a possible route for p-type doping

Abstract

Using theory and experiment, we address a possible p-type doping route of GaN using the Be acceptor. Hybrid functional calculations suggest that straightforward incorporation of Be in GaN will likely lead to compensated high resistivity samples. In this case, beryllium interstitials and nitrogen vacancies are the most likely compensating donors. However, calculations also show that simultaneous incorporation of beryllium and hydrogen in the nitrogen-rich growth regime is likely to lead to the formation of neutral BeGa-Hi complexes. These complexes are energetically favorable and do not exhibit any transition levels in the bandgap. Subsequent annealing in hydrogen-free or nitrogen ambient will dissociate these complexes and activate shallow BeGa acceptors in GaN. Experimental measurements, where an ultraviolet photoluminescence band related to the shallow BeGa acceptor emerges after annealing the Be-doped GaN, confirm these findings.