Dislocation Evolution and Microstructural Properties on GaN Grown on Cone Patterned Sapphire Substrate


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Abstract

GaN epifilms are grown on the cone patterned sapphire substrates (CPSS) and the conventional sapphire substrates (CSS) by metal-organic chemical vapor deposition (MOCVD) using a two-step growth. We investigated dislocation structures and density in the GaN epifilms grown on CPSS and CSS using high resolution X-ray diffraction (HRXRD) and transmission electron microscopy (TEM). HRXRD measurement shows that GaN epifilms grown on CPSS have lower dislocation density than the CSS, especially the edge dislocation density. This consequence is confirmed by metallographs of etched GaN. From the TEM results, we found that most of the threading dislocations (TDs) in the trench region of the CPSS were bent by lateral growth mode. The bending of dislocations and presence of voids dramatically prevent the generation of threading dislocations on the surface due to the induced lateral overgrowth mode. The high Raman peak intensity of the GaN epifilms grown on CPSS with a low full width at half maximum (FWHM) indicates that there is an improvement in the quality of the GaN compared to GaN epifilms grown on CSS.

About the authors

Huanyou Wang

Academy of Electronic Information and Electrical Engineering, Xiangnan University

Author for correspondence.
Email: whycs@163.com
China, Chenzhou, 423000

Gui Jin

Academy of Electronic Information and Electrical Engineering, Xiangnan University; School of Information and Optoelectronics Science and Technology, South China Normal University

Email: whycs@163.com
China, Chenzhou, 423000; Guangzhou, 510631

Qiaolai Tan

Academy of Electronic Information and Electrical Engineering, Xiangnan University; Institute of Physics and Information Science, Hunan Normal University

Email: whycs@163.com
China, Chenzhou, 423000; Changsha, 410081

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