Effect of different well growth rates on the luminescence characteristics of InGaN/GaN green quantum well

Abstract

Four InGaN/GaN multi-quantum well (MQW) samples with different InGaN quantum well growth rates grow via metal-organic chemical vapor deposition (MOCVD) system. The relationship between the growth rate and luminescence characteristics of multiple quantum wells is studied by analyzing the temperature-dependent photoluminescence (TDPL) spectra, and microscopy photoluminescence image. The results show that the uniformity and internal quantum efficiency (IQE) of the samples become better first and then deteriorate as the growth rate increases. Whether the growth rate is too high or too low, it will cause the uniformity and IQE of the sample to deteriorate. The following two reasons lead to poor material uniformity. When the growth rate is too slow, the mobility of In atoms is higher than that of Ga atoms, forming In enrichment on the sample surface; on the contrary, the migration time of atoms is not enough, and Ga atoms cannot move to the lattice site. We also find when the growth rate is 0.0125 nm s−1, the sample has the best uniformity, and when the growth rate is 0.034 nm s−1, the IQE of the sample is the highest at room temperature.