Radiative N-localized recombination and confinement in GaAsN/GaAs epilayers and quantum well structures

The photoluminescence (PL) properties of GaAsN/GaAs epilayers and single quantum wells (QWs) have been investigated as a function of the excitation density and the sample temperature (10–300 K). At low temperatures, the PL spectra were sensitive to the excitation density for epilayers and QWs. For both structures, a blue shift of the PL peak is noted with increasing the excitation power. In contrast, the temperature dependence shows different behaviors for the bulk epilayers and for the quantum wells structures. An S-shape of the PL peak energy versus temperature has been observed for the GaAsN/GaAs epilayer while the QWs peak energy decreases monotically with the sample temperature and could be fitted by conventional Varshni’s law. This behavior is due to the exciton localization effect which is induced by the local fluctuation of nitrogen concentration.