The direct evidence of the composition pulling effect and its role in InGaN multiple quantum wells

Direct evidence of composition pulling effect (CPE) in InGaN' quantum wells was obtained by combining energy dispersive x-ray spectrometry (EDS) and scanning tunneling electron microscope (STEM). The indium content increases along the c-axis in the InGaN quantum wells, forming an In-rich sublayer on the surface. The indium content in the In-rich sub -layer will reach saturation earlier. After that, the incorporation of indium atoms is hin-dered, resulting in a decrease in the average indium composition in the InGaN quantum wells. Moreover, an aggregation behavior of indium atoms has been observed in samples with a stronger CPE. This leads to a lot of dark spot defects, seriously deteriorating the luminescence quality. By restricting the migration ability of indium atoms, dark spot de-fects could be greatly suppressed, and a higher quality InGaN/GaN MQW with higher in-dium content was obtained. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).