Lifetime enhancement of the exciton in a trapezoidal-type InGaN/GaN multi-quantum well structure

A trapezoidal InGaN/GaN multi-quantum well structure was grown by metal-organic chemical vapor deposition and the relaxed interface was compared to a conventional square well structure. The time-resolved photoluminescence measurement provides the fast components of the recombination lifetimes of 0.32-0.33 ns with the corresponding oscillator strengths of 2.09-2.15 for both samples. However, the slow component shows the long tail in square quantum wells rather than in trapezoidal quantum wells. This indicates that the later structure is more radiative by forming quantum dots, which is consistent with the microstructure of multi-quantum wells.