The effects of indium concentration and well-thickness on the mechanisms of radiative recombination in In x Ga 1−x N quantum wells

A correlation of the local indium concentration measured on an atomic scale with luminescence properties of In x Ga 1−x N quantum wells reveals two different types of recombination mechanisms. A piezoelectric-field based mechanism is shown to dominate in samples with thick wells (L > 3 nm) of low indium concentration (x < 0.15−0.20). Spatial indium concentration fluctuations dominate luminescence properties in samples of higher indium concentrations in thinner wells. Quantum confinement is shown to have a major effect on the radiative recombination energy. A model is presented that relates the experimentally measured nano scale structural and chemical properties of quantum wells to the characteristics of the luminescence.