Photoluminescence studies of GaN and InGaN/GaN quantum wells

We present data for the photoluminescence produced by two-photon excitation in a GaN epilayer and a InGaN/GaN multiple quantum well grown on sapphire substrates by using metal-organic chemical-vapor deposition. We roughly estimated the two photon absorption coefficient at 1.79 eV in GaN and at 1.63 eV in In0.13Ga0.17N/GaN at 10 K. The temperature dependences of the photoluminescence spectra and the decay times were employed to study the radiative and the nonradiative recombination processes of the excitons in the range of 10 similar to 300 K. Their activation energies were also obtained. Cody formula was employed to explain the temperature dependence of the bandgap energy in GaN.