Evidence for shallow acceptors in GaN

Two low-temperature photoluminescence lines in GaN, in the region of energies commonly interpreted as longitudinal optical-phonon replicas of free excitons, donor-bound excitons, or acceptor-bound excitons, are reinterpreted as acceptor-bound excitons (AX's) collapsing to n = 2 and n = 3 excited states, respectively, of the acceptors involved. Application of this model to two sets of AX-related lines in hydride-vapor-phase-grown GaN gives acceptor energies of 85±1, and 115±1 meV, respectively. The existence of such shallow acceptor states, if confirmed, is of great technological importance. © 2001 American Institute of Physics.