| Original Articles |
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Effect of III/V Ratio of HT-AlN Buffer Layer on Polarity Selection and Electrical Quality of GaN Films Grown by Radio Frequency Molecular Beam Epitaxy |
| ZHONG Fei;QIU Kai;LI Xin-Hua;YIN Zhi-Jun;XIE Xin-Jian;WANG Yang;JI Chang-Jian;CAO Xian-Cun;HAN Qi-Feng;CHEN Jia-Rong;WANG Yu-Qi |
| Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 |
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| Cite this article: |
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ZHONG Fei, QIU Kai, LI Xin-Hua et al 2007 Chin. Phys. Lett. 24 240-243 |
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Abstract We investigate the effect of Al/N ratio of the high temperature (HT) AlN buffer layer on polarity selection and electrical quality of GaN films grown by radio frequency molecular beam epitaxy. The results show that low Al/N ratio results in N-polarity GaN films and intermediate Al/N ratio leads to mixed-polarity GaN films with poor electrical quality. GaN films tend to grow with Ga polarity on Al-rich AlN buffer layers. GaN films with different polarities are confirmed by in-situ reflection high-energy electron diffraction during the growth process. Wet chemical etching, together with atomic force microscopy, also proves the polarity assignments. The optimum value for room-temperature Hall mobility of the Ga-polarity GaN film is 703cm2/V.s, which is superior to the N-polarity and mixed-polarity GaN films.
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81.95.Ea
81.15.Hi
61.14.Hg
81.65.Cf
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Published: 01 January 2007
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