Influence of Low-Temperature Cap Layer Thickness on Luminescence Characteristics of Green InGaN/GaN Quantum Wells

• Published in: Materials Vol. 16; no. 4; p. 1558
• Main Authors: Sun, Haoran, Chen, Yuhui, Ben, Yuhao, Zhang, Hongping, Zhao, Yujie, Jin, Zhihao, Li, Guoqi, Zhou, Mei
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13.02.2023; MDPI
• Subjects: cap layer; Chemical vapor deposition; Efficiency; Gallium nitrides; Indium gallium nitrides; InGaN/GaN MQW; Lasers; Light emitting diodes; Liquors; localized state; Low temperature; Luminescence; luminescence characteristics; Multi Quantum Wells; Photoluminescence; Point defects; Quantum wells; Temperature; Temperature dependence; Thickness; China; luminescence characteristics; InGaN/GaN MQW; localized state; cap layer
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16041558

GaN cap layer with different thicknesses was grown on each InGaN well layer during MOCVD growth for InGaN/GaN multiple quantum well (MQW) samples to study the influence of the cap layer on the photoluminescence (PL) characteristics of MQWs. Through the temperature-dependent (TD) PL spectra, it was found that when the cap layer was too thick, the localized states of the quantum wells were relatively non-uniform. The thicker the well layer, the worse the uniformity of the localized states. Furthermore, through micro-area fluorescence imaging tests, it was found that when the cap layer was too thick, the luminescence quality of the quantum well was worse. In summary, the uniformity of the localized states in the quantum wells and the luminescence characteristics of the quantum wells could be improved when a relatively thin cap layer of the quantum well was prepared during the growth. These results could facilitate high efficiency QW preparation, especially for green LEDs.