| CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES |
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Morphological Evolution of a-GaN on r-Sapphire by Metalorganic Chemical Vapor Deposition |
| SANG Ling**, LIU Jian-Ming, XU Xiao-Qing, WANG Jun, ZHAO Gui-Juan, LIU Chang-Bo, GU Cheng-Yan, LIU Gui-Peng, WEI Hong-Yuan, LIU Xiang-Lin**, YANG Shao-Yan, ZHU Qin-Sheng, WANG Zhan-Guo |
Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083
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| Cite this article: |
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ZHAO Gui-Juan, XU Xiao-Qing, WEI Hong-Yuan et al 2012 Chin. Phys. Lett. 29 026801 |
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Abstract The morphological evolution of a-GaN deposited by metalorganic chemical vapor deposition (MOCVD) on r-sapphire is studied. The influences of V/III ratio and growth temperature on surface morphology are investigated. V−pits and stripes are observed on the surface of a-GaN grown at 1050°C and 1100°C, respectively. The overall orientation and geometry of V−pits are uniform and independent on the V/III molar ratio in the samples grown at 1050°C, while in the samples grown at 1100°C, the areas of stripes decrease with the adding of V/III ratio. We deduce the origin of V−pits and stripes by annealing the buffer layers at different temperatures. Because of the existence of inclined (1011) facets, V−pits are formed at 1050°C. The (1011) plane is an N terminated surface, which is metastable at higher temperature, so stripes instead of V−pits are observed at 1100°C. Raman spectra suggest that the growth temperature of the first layer in the two-step process greatly affects the strain of the films. Hence, to improve the growth temperature of the first layer in the two-step method may be an effective way to obtain high quality a-GaN film on r-sapphire.
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| Keywords:
68.37.Hk
81.05.Ea
81.15.Gh
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Received: 16 August 2011
Published: 11 March 2012
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| PACS: |
68.37.Hk
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(Scanning electron microscopy (SEM) (including EBIC))
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81.05.Ea
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(III-V semiconductors)
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81.15.Gh
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(Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.))
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