Luminescent properties of GaN thin films prepared by pulsed laser deposition

The luminescent properties of GaN thin films grown by pulsed laser deposition have been studied to understand the nature of the luminescent centres and the recombination dynamics. The films were grown on heated sapphire substrates using KrF excimer laser ablation of GaN in a reactive atmosphere of nitrogen. At low temperature the continuous wave (CW) blue luminescence of the samples grown shows two sharp lines attributed to excitonic recombination localized at extended defects. An analysis of the temperature dependence of photoluminescence (PL) lifetimes assesses the relative contributions of radiative and non-radiative recombination in the centres responsible for these emissions. The measurement of room temperature nanosecond radiative lifetimes for these lines supports the excitonic attribution of the luminescence.