Carrier localization in green emitting InGaN/GaN multiquantum well structure

Green emitting InGaN/GaN multiquantum well sample is investigated using photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectroscopy. Carrier localization of energy $\sim$ 12 meV due to inhomogeneous distribution of In in the InGaN quantum well (QW) layer is observed. The temperature dependence of PL peak energy exhibits S-shape phenomenon and is comparatively discussed with the Varshni's empirical formula. The full width at half maximum (FWHM) of the PL emission band shows increasing-decreasing-increasing behavior with increase in temperature. The temperature dependence of radiative life time ($\tau_{\mathrm{r}})$ show $\tau_{\mathrm{r}}$ $\sim$ $T^{3/2}$ dependence with temperature above 200 K which confirms the insignificant effect of carrier localization at room temperature. Transmission electron microscopy (TEM) study reveals the absence of In-rich regions known for strong carrier localization in the InGaN QW layer which is consistent with the results of PL and TRPL.