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论文类型：期刊论文
发表时间：2015-02-05
发表刊物：JOURNAL OF ALLOYS AND COMPOUNDS
收录刊物：SCIE、EI
卷号：621
页面范围：12-17
ISSN号：0925-8388
关键字：AlInGaN quaternary alloy; Multiple quantum wells; Recombination mechanism; Temperature-dependent; photoluminescence; Localized effect
摘要：The structural and optical properties of In0.20Ga0.80N/AlxInyGa1 (x) N-y multiple quantum wells samples with varying Al content in barrier layers grown on sapphire substrates by metalorganic chemical vapor deposition have been investigated by means of high-resolution X-ray diffraction, Raman scattering measurements and temperature-dependent photoluminescence. Raman measurements verified the existence of In-rich clusters in ternary and quaternary layers. At 10 K and 300 K, the PL spectrum of each sample is dominated by a sharp emission peak arising from In0.20Ga0.80N well layers. The anomalous temperature-dependent S-shaped behaviors of emission energies have been observed, indicating the presence of localized states induced by the potential fluctuations in the quantum wells due to the inhomogeneous distribution of In-rich clusters. The degree of the localization effect and the transition temperatures between different temperature regions can be enhanced by increasing Al content in barrier layers. The improvement of the localized states emission has been observed at the lower energy side of band gap emission of quantum wells with increasing Al content. The origin of the deep localized states could be attributed to the larger quantum-confined Stark effect in the quantum wells with higher Al content. The recombination mechanism of carriers between band edge and localized states was proposed for interpreting of the emission characteristics. (C) 2014 Elsevier B.V. All rights reserved.