Effect of strain relaxation in InGaN/GaN multi-quantum wells with self-assembled Pt nanoclusters.

: We report effect of the strain relaxation in InGaN/GaN multi-quantum well (MQW) structures grown on platinum nanocluster-coated sapphire substrate (PNSS) by metal organic chemical vapor deposition. The photoluminescence (PL) intensity of InGaN/GaN MQWs on PNSS was significantly enhanced compared to that of the InGaN/GaN MQWs on flat sapphire substrate due to the reduction of defect density and residual strain by self-assembled Pt nanoclusters. We confirmed the reduction of strain-induced piezoelectric field by the power dependence of the PL in InGaN/GaN MQWs on PNSS. Cathodoluminescence shows that a large bright area with overall strong peak intensity is attributed to the suppression of In inhomogeneity and strain relaxation in InGaN/GaN MQWs on PNSS. Based on these results, we suggest that the self-assembled Pt nanocluster can be applied to increase the quantum efficiency through improved crystal quality and internal strain relaxation in MQWs.