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论文类型：期刊论文
发表时间：2015-12-01
发表刊物：NANOSCALE RESEARCH LETTERS
收录刊物：SCIE、EI、PubMed、Scopus
卷号：10
期号：1
页面范围：459
ISSN号：1556-276X
关键字：Semi-polar; InGaN/GaN multi-quantum wells; Cathodoluminescence; Photoluminescence
摘要：InGaN/GaN multi-quantum wells (MQWs) are grown on (0001) sapphire substrates by metal organic chemical vapor deposition (MOCVD) with special growth parameters to form V-shaped pits simultaneously. Measurements by atomic force microscopy (AFM) and transmission electron microscopy (TEM) demonstrate the formation of MQWs on both (0001) and (1 (1) over bar 01) side surface of the V-shaped pits. The latter is known to be a semi-polar surface. Optical characterizations together with theoretical calculation enable us to identify the optical transitions from these MQWs. The layer thickness on (1 (1) over bar 01) surface is smaller than that on (0001) surface, and the energy level in the (1 (1) over tilde 01) semi-polar quantum well (QW) is higher than in the (0001) QW. As the sample temperature is increased from 15 K, the integrated cathodoluminescence (CL) intensity of (0001) MQWs increases first and then decreases while that of the (1 (1) over bar 01) MQWs decreases monotonically. The integrated photoluminescence (PL) intensity of (0001) MQWs increases significantly from 15 to 70 K. These results are explained by carrier injection from (1 (1) over bar 01) to (0001) MQWs due to thermal excitation. It is therefore concluded that the emission efficiency of (0001) MQWs at high temperatures can be greatly improved due to the formation of semi-polar MQWs.