Excitation intensity dependence of free-exciton transitions in GaN grown by low-pressure metallorganic chemical vapor deposition

The excitation intensity dependence of photoluminescence (PL) of free-exciton (FX) A and B in undoped GaN single crystal grown by metal organic chemical vapor deposition (MOCVD) is reported. The variation of emission intensity, line width, energy peak positions and recombination lifetime with excitation intensities is presented and discussed. The results show that the sample is very pure and the recombination lifetime of FX in the GaN crystal is governed by the radiative processes.