Recombination dynamics of localized excitons in cubic phase In_xGa_1-xN/GaN multiple quantum wells on 3C-SiC/Si (001)

Recombination dynamics of localized excitons in strained cubic (c-)In_xGa_1-xN/c-GaN multiple quantum wells (MQWs) were studied. In contrast to hexagonal (h-)InGaN quantum wells (QWs), low-excitation photoluminescence (PL) peak energy increased moderately with decreasing well thickness L and the PL decay time did not depend on L. The results indicated that piezoelectric field had negligible influence on the transition processes. The time-resolved photoluminescence (TRPL) signal showed a stretched exponential decay up to 300 K, showing that the spontaneous emission is due to the radiative recombination of excitons localized in disordered quantum nano-structures even at 300 K. Decrease in internal quantum efficiency (n), which is related to the increase in quasi-radiative lifetime, with the increase in temperature was explained to be due to reduced localization rate.