Strain Distributions in Non-Polar a-Plane InxGa1?xN Epitaxial Layers on r-Plane Sapphire Extracted from X-Ray Diffraction
ZHAO Gui-Juan**, YANG Shao-Yan**, LIU Gui-Peng, LIU Chang-Bo, SANG Ling, GU Cheng-Yan, LIU Xiang-Lin, WEI Hong-Yuan, ZHU Qin-Sheng, WANG Zhan-Guo
1Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083 2Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083
Abstract：By using x-ray diffraction analysis, we investigate the major structural parameters such as strain state and crystal quality of non-polar a-plane InxGa1?xN thin films grown on r-sapphire substrates by metalorganic chemical vapour deposition. The results of the inplane grazing incidence diffraction technique are analyzed and compared with a complementary out-of-plane high resolution x-ray diffraction technique. When the indium composition is low, the a-plane InxGa1?xN layer is tensile strain in the growth direction (a-axis) and compressive strain in the two in-plane directions (m-axis and c-axis). The strain status becomes contrary when the indium composition is high. The stress in the m-axis direction σyy is larger than that in the c-axis direction σzz. Furthermore, strain in the two in-plane directions decrease and the crystal quality becomes better with the growing of the InxGa1?xN film.
2013, Vol. 30 
