Abstract
Peculiarities of the excitation-dependent photoluminescence (PL) lineshape in Ga(NAsP)/GaP multiple quantum well structures are studied both experimentally and theoretically. A peculiar behavior of the PL peak energy and PL full width at half maximum (FWHM) at low temperatures is revealed experimentally. The PL peak energy increases with the increasing excitation intensity and tends to saturation at high excitation intensities, reflecting the gradual filling of the disorder-induced localized states. The PL FWHM initially decreases with the increasing excitation intensity, reaching a minimum at a relatively high excitation intensity, and then increases for higher excitation intensities. Such a non-monotonous behavior of the PL lineshape is explained by the hopping relaxation of excitons in the tail of localized states, assuming a non-monotonous density of localized states, consisting of exponential and Gaussian components.