Influence of InN mole fraction on the recombination processes of localized excitons in strained cubic InxGa1-xN/GaN multiple quantum wells

Recombination dynamics of localized excitons in the best quality strained cubic InxGa1-xN/GaN multiple quantum wells (MQWs) grown on 3C-SiC (001) were studied as functions of InN mole fraction x and temperature T. The MQWs exhibited large Stokes-type shifts although the full width at half maximum of the photoluminescence (PL) peaks being 80-120 meV is 100-300 meV smaller than those reported previously. Time-resolved PL signal showed stretched exponential decay and spectral redshift with time after excitation up to 300 K. These results are fingerprints that the spontaneous emission is due to the radiative recombination of excitons localized in disordered quantum nanostructures forming extended and localized states. Effective localization depth increased with the increase in x, which gave rise to fast exciton localization. However, nonradiative lifetime in the free states decreased more rapidly with the increase in x and T, giving the emission efficiency maximum at particular x around 0.1. (C) 2003 American Institute of Physics.