Band-tail model and temperature-induced blue-shift in photoluminescence spectra of InxGa1-xN grown on sapphire

A band-tail model of inhomogeneously broadened radiative recombination is p resented and applied to interpret experimental, data on photoluminescence o f various bulk and quantum-well epitaxial InGaN/GaN structures grown by MOC VD. The temperature dependence of the spectral peak position is analyzed ac cording to the model, explaining the anomalous temperature-induced blue spe ctral shift. Significant differences are observed between epilayers grown o n sapphire substrates and on GaN substrates prepared by the sublimation met hod. No apparent evidence of band tails in homoepitaxial structures indicat es their higher crystalline quality.