Compositional disorder in GaAs1-xNx: H investigated by photoluminescence

Compositional disorder is investigated by means of photoluminescence (PL) and PL excitation (PLE) measurements in as-grown and hydrogen-irradiated GaAs1-xNx samples (x <= 0.21%). The dependence of the linewidth of the PLE free-exciton band on N concentration agrees well with that predicted by a theoretical model developed for a purely random alloy. We also find that hydrogen irradiation and ensuing nitrogen passivation reduce significantly the broadening of the free-exciton band. This result is consistent with a removal by hydrogen of the static disorder caused by nitrogen. Finally, an analysis of the dependence of the Stokes shift on the free-exciton linewidth shows that free carriers are thermalized even at low temperature, another indication of a low degree of disorder in the investigated samples.