Luminescence study of (1120) GaN film grown by metalorganic chemical-vapor deposition

Investigations on photoluminescence properties of (112̄0) GaN grown on (11̄02) Al2O3 substrate by metalorganic chemical-vapor deposition are reported. Several emission lines not reported before are observed at low temperature. The sharp peak at 3.359 eV is attributed to the exciton bound to the neutral acceptor. Another peak at 3.310 eV represents a free-to-bound, probably a free electron-to-acceptor, transition. The 3.241 and 3.170 eV lines are interpreted as phonon replica lines of the 3.310 eV line. The phonon energy is 70 meV, consistent with the energy of transverse optical E1 phonon. The optical properties of the lines are analyzed.