Localized exciton dynamics in strained cubic In0.1Ga0.9N/GaN multiple quantum wells

Radiative and nonradiative recombination dynamics in strained cubic $\mathrm{(c-)}$ ${\mathrm{In}}_{\mathrm{0.1}}{\mathrm{Ga}}_{\mathrm{0.9}}\mathrm{N}\mathrm{/c-}\mathrm{GaN}$ multiple quantum wells were studied using temperature-dependent time-resolved photoluminescence (TRPL) spectroscopy. In contrast to hexagonal InGaN quantum wells, low-excitation photoluminescence peak energy increased moderately with decreasing well thickness $L$ and the PL lifetime did not strongly depend on $\mathrm{L.}$ The results clearly indicated that the piezoelectric field was not acting on the transition process. The TRPL signal was well fitted as a stretched exponential decay from 10 to 300 K, showing that the spontaneous emission is due to the radiative recombination of excitons localized in disordered quantum nanostructures such as In clusters. The localized states were considered to have two-dimensional density of states at 300 K (quantum disk size), since the radiative lifetime increased with increasing temperature above 150 K.