Origin Of Thermal Quenching Of Exciton Photoluminescence In Aigan Epilayers

Dynamics of a low-density exciton system is simulated using the kinetic Monte Carlo algorithm. The temperature dependences of photoluminescence (PL) intensity and PL band Stokes shift in a high-Al-content AlGaN epilayer are calculated and fitted to the experimentally measured ones. The key features of nonradiative recombination via delocalized states and direct tunnelling to nonradiative recombination centres and their influence on PL efficiency are analysed. A strong influence of the tunnelling-based recombination in AlGaN epilayers with a large ratio between the densities of nonradiative recombination centres and localized states is revealed.