Liu, Jianming and Liu, Xianlin and Li, Chengming and Wei, Hongyuan and Guo, Yan and Jiao, Chunmei and Li, Zhiwei and Xu, Xiaoqing and Song, Huaping and Yang, Shaoyan and Zhu, Qinsen and Wang, Zhanguo and Yang, Anli and Yang, Tieying and Wang, Huanhua (2011) Investigation of cracks in GaN films grown by combined hydride and metal organic vapor-phase epitaxial method. Nanoscale Research Letters, 6 (1). pp. 1-8.
Official URL: http://www.nanoscalereslett.com/content/6/1/69
Cracks appeared in GaN epitaxial layers which were grown by a novel method combining metal organic vapor-phase epitaxy (MOCVD) and hydride vapor-phase epitaxy (HVPE) in one chamber. The origin of cracks in a 22-μm thick GaN film was fully investigated by high-resolution X-ray diffraction (XRD), micro-Raman spectra, and scanning electron microscopy (SEM). Many cracks under the surface were first observed by SEM after etching for 10 min. By investigating the cross section of the sample with high-resolution micro-Raman spectra, the distribution of the stress along the depth was determined. From the interface of the film/substrate to the top surface of the film, several turnings were found. A large compressive stress existed at the interface. The stress went down as the detecting area was moved up from the interface to the overlayer, and it was maintained at a large value for a long depth area. Then it went down again, and it finally increased near the top surface. The cross-section of the film was observed after cleaving and etching for 2 min. It was found that the crystal quality of the healed part was nearly the same as the uncracked region. This indicated that cracking occurred in the growth, when the tensile stress accumulated and reached the critical value. Moreover, the cracks would heal because of high lateral growth rate.
|Subjects:||Physical Science > Nano objects|
Material Science > Nanostructured materials
Material Science > Nanochemistry
|Divisions:||Faculty of Engineering, Science and Mathematics > School of Chemistry|
|Deposited On:||20 Oct 2011 10:13|
|Last Modified:||20 Oct 2011 10:13|
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