Temperature and excitation intensity dependence of photoluminescence in AlGaN quantum wells with mixed two-dimensional and three-dimensional morphology

The temperature dependences of the time-integrated and time-resolved photoluminescence (PL) properties for AlGaN multiple quantum wells are examined. The wells are grown so that a range of mixed two-dimensional (2D) and three-dimensional (3D) morphology is obtained, ranging from primarily 2D to primarily 3D. The temperature dependence of the band edge is studied using absorption spectroscopy and found to be described by electron-phonon interactions. The temperature dependence of the PL emission intensities and lifetimes are described by a model incorporating the effects of thermal activation and hopping, both of which compete with the radiative process. These factors are smaller than the observed Stokes shift between absorption and emission, and attributed to intra-well electron transfer that varies according to 2D and 3D character. High excitation intensity reveals two PL bands in the sample with intermediate 2D/3D well morphology. The intensity dependence is described based on screening and bandgap reno...