Effect of InGaN growth interruption on photoluminescence properties of an InGaN-based multiple quantum well structure

摘要

Two different green-emitting InGaN-based multiple quantum well (MQW) structures, with and without two-step growth interruption (TSGI) during InGaN well layer growth, were prepared, and their optical properties were investigated by examining the dependences of photoluminescence (PL) spectra on temperature and excitation power. The results indicate that, compared to the MQW structure without TSGI, the MQW structure with TSGI exhibits a higher PL peak energy, narrower linewidth, and a weaker carrier localization effect and quantum confined Stark effect within the chosen measurement range. These results are due to the fact that a TSGI can reduce the average In content and result in a more homogeneous distribution of In atoms in the MQWs due to In re-evaporation and diffusion of In atoms from indium-rich to indium-poor regions, and thus causing a less significant In composition fluctuation and a weaker polarized electric field in the MQWs. It is also consistent with the experimental result, in which the MQW structure with TSGI has a higher internal quantum efficiency compared with the MQW structure without TSGI, due to it having fewer non-radiative centers as confirmed by measuring excitation power-dependent integrated PL intensity.