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Yang D.,Jilin University | Liang H.,Dalian University of Technology | Liang H.,CAS Shanghai Institute of Microsystem and Information Technology | Qiu Y.,Dalian University of Technology | And 8 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2014

GaN epilayer was grown on a new polyhedral patterned sapphire substrate (new PSS) by metal-organic chemical vapor deposition. The new PSS was prepared by combining the dry etching technique and wet etching technique. The X-ray diffraction indicated that the full width at half maximum values of (0002) and (1012) diffraction peaks in the GaN epilayer grown on the new PSS were evidently smaller than that in the GaN epilayer grown on the normal treated PSS. The improvement of GaN quality was attributed to the reduction of threading dislocations (TDs) in GaN epilayer, and the mechanism of the reduction of TDs was analyzed. The influence of the new PSS on the optical properties as well as the residual stress in GaN epilayer was also discussed. © Springer Science+Business Media New York 2013.


Yang D.-C.,Jilin University | Liang H.-W.,Dalian University of Technology | Liang H.-W.,CAS Shanghai Institute of Microsystem and Information Technology | Qiu Y.,Dalian University of Technology | And 7 more authors.
Faguang Xuebao/Chinese Journal of Luminescence | Year: 2013

GaN-based light emitting diodes (LEDs) were grown on the sapphire substrates with different bow values by low pressure metal organic chemical vapor deposition (MOCVD). LED chips were fabricated and the optic and electronic parameters were characterized. The influence of different bow values on the performances of LED was investigated. The analysis results show that the substrates with bow could relax part of the stress in the epilayer beforehand, which improved the quality of epilayer. Hence, the performances of the LED chips got better. During the growth of LEDs, the InGaN material in the active layer suffered the compressive stress that resulted from the underneath GaN layer. With the increase of bow values, the compressive stress that acted on the InGaN material decreased, which leads to the blue shift of the dominant wavelength.


Yang D.,Jilin University | Yang D.,Dalian University | Liang H.,Dalian University of Technology | Liang H.,CAS Shanghai Institute of Microsystem and Information Technology | And 10 more authors.
Applied Surface Science | Year: 2014

A series of wet etching experiments were performed to investigate the evolution of crystallographic planes of cone-shaped patterned sapphire substrate. During the etching process, three kinds of etching zones were found. Two etching zones appeared first and vanished with increasing etching time. The other one exposed later and expanded gradually. Finally, the cone-shaped pattern with an arcuate slope transformed to a hexagonal pyramid. The calculated orientation of the crystallographic planes in the two etching zones was {1 1̄ 0 3} and {4 3̄ 1̄ 27}, which were different from the previous reports. © 2014 Elsevier B.V. All rights reserved.


Yang D.,Jilin University | Yang D.,Dalian University | Liang H.,Dalian University of Technology | Liang H.,CAS Shanghai Institute of Microsystem and Information Technology | And 10 more authors.
Chemical Research in Chinese Universities | Year: 2014

Cone-shaped patterned sapphire substrate was prepared by inductively coupled plasma etching and GaN nucleation layer was grown on it by metal-organic chemical vapor deposition. A selective growth of GaN nucleation layer was found on the slope of the cone-shaped patterned sapphire substrat, and the distribution morphology of GaN had significantly changed after it was recrystallized. GaN selective growth and redistribution were analyzed by investigating the distribution of crystallographic planes on the cone surface and the atom array of specific planes at atom level. © 2014 Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH.

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