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Mosaic Structure Evolution in GaN Films with Annealing Time Grown by Metalorganic Chemical Vapour Deposition |
| CHEN Zhi-Tao1,2,3;XU Ke1,2,3;GUO Li-Ping4;YANG Zhi-Jian1,2,3;PAN Yao-Bo1,2,3;SU Yue-Yong1,2,3;ZHANG Han1,2,3;SHEN Bo1,2,3;ZHANG Guo-Yi1,2,3 |
| 1School of Physics, Peking University, Beijing 100871
2State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871
3Research Center for Wide-band Semiconductors, Peking University, Beijing 100871
4Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 |
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| Cite this article: |
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CHEN Zhi-Tao, XU Ke, GUO Li-Ping et al 2006 Chin. Phys. Lett. 23 1257-1260 |
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Abstract We investigate mosaic structure evolution of GaN films annealed for a long time at 800°C grown on sapphire substrates by metalorganic chemical vapour deposition by high-resolution x-ray diffraction. The result show that residual stress in GaN films is relaxed by generating edge-type threading dislocations (TDs) instead of screw-type TDs. Compared to as-grown GaN films, the annealed ones have larger mean twist angles corresponding to higher density of edge-type TDs but smaller mean tilt angles corresponding to lower density of screw-type TDs films. Due to the increased edge-type TD density, the lateral coherence lengths of the annealed GaN films also decrease. The results obtained from chemical etching experiment and grazing-incidence x-ray diffraction (GIXRD) also support the proposed structure evolution.
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| Keywords:
61.72.Dd
61.72.Cc
61.10.Nz
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Published: 01 May 2006
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| PACS: |
61.72.Dd
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(Experimental determination of defects by diffraction and scattering)
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61.72.Cc
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(Kinetics of defect formation and annealing)
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61.10.Nz
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