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
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
摘要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.
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.
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. Morphological Evolution of a-GaN on r-Sapphire by Metalorganic Chemical Vapor Deposition[J]. 中国物理快报, 2012, 29(2): 26801-026801.
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. Morphological Evolution of a-GaN on r-Sapphire by Metalorganic Chemical Vapor Deposition. Chin. Phys. Lett., 2012, 29(2): 26801-026801.
[1] Sun W H et al 2003 Appl. Phys. Lett. 83 2599
[2] Craven M D et al 2002 Abstract (L4.3) of M.RS (Fall Meeting Boston 2–6 December 2002)
[3] Ng H M 2002 Appl. Phys. Lett. 80 4369
[4] Craven M D et al 2002 Appl. Phys. Lett. 81 1201
[5] Ma B et al 2009 Appl. Phys. Lett. 95 121910
[6] Haskell B A et al 2005 Appl. Phys. Lett. 86 111917
[7] Lymperakis L and Neugebauer J 2009 Phys. Rev. B 79 241308
[8] Wu F et al 2003 J. Appl. Phys. 94 942
[9] Miyagawa R et al 2008 J. Cryst. Growth 310 4979
[10] Ruterana P et al 2003 Nitride Semiconductors Handbook on Materials and Devices (Berlin: WILEY VCH Verlag GmbH &Co, KGaA, Weinheim)
[11] Hiramatsu K et al 1999 Phys. Stat. Sol. 176 535
[12] Liu H P et al 2004 J. Cryst. Growth 260 79
[13] Gavini A and Cardona M 1970 Phys. Rev. B 1 672
[14] Goni A R et al 2001 Phys. Rev. B 64 035205
2012, Vol. 29 
