Evolution of electronic states in GaP_1−xN_x studied by resonant Raman scattering spectroscopy

Two distinct maxima E_W and E_W′ are observed in the resonant Raman scattering profile for the zone-center longitudinal-optical phonon asymmetric linewidth broadening in GaP_1−xN_x. E_W originates from the X-point conduction-band state perturbed by isolated nitrogen state N_X and the nitrogen-nitrogen (NN) pair and cluster states, and E_W′ from the effective band-edge states which are comprised of NN pairs and clusters. The study reveals that E_W remains stationary with increased nitrogen doping whereas E_W′ closely follows the absorption edge.