Carrier capture times in InGaN/GaN multiple quantum wells

We have investigated the temperature and carrier density dependence of the carrier capture time of two optically pumped InGaN/GaN multiple quantum well laser structures by subpicosecond time-resolved differential transmission spectroscopy. We find that the carrier capture time varies significantly with both the temperature and the carrier density. The carrier density dependence is consistent with screening of piezoelectric fields, in agreement with theoretical predictions. The sample with the lower threshold for stimulated emission has a faster carrier capture rate, which highlights the importance of carrier capture for the lasing process. At room temperature the capture time is less than 1.2 ps in both samples.