標題: High-Quality Free-standing GaN Thick-films Prepared by Hydride Vapor Phase Epitaxy using Stress Reducing Techniques
作者: Huang, Hsin-Hsiung
Lee, Wei-I
Chen, Kuei-Ming
Chu, Ting-Li
Wu, Pei-Lun
Yu, Hung-Wei
Liu, Po-Chun
Chao, Chu-Li
Chi, Tung-Wei
Tsay, Jenq-Dar
Tu, Li-Wei
電子物理學系
Department of Electrophysics
關鍵字: HVPE;GaN;LLO;freestanding;residual stress
公開日期: 2009
摘要: As one of the most mature techniques for manufacturing free-standing GaN substrates, hydride vapor phase epitaxy (HVPE) always encounters problems associated with residue thermal stress, such as GaN bending and cracking during and after growth. This work presents a patterning approach and a non-patterning approach to reduce stress in thick GaN films grown on sapphires by HVPE. The patterning approach, forming dot air-bridged structures, adopted standard photolithography to fabricate hexagonally aligned patterns of dots on GaN templates. Following HVPE growth, regular voids were formed and buried in the GaN thick-films. These voids helped to relax the stress in the GaN thick-films. In the non-patterning approach, thick GaN films were simply grown at a specially set sequence of ramping temperatures during HVPE growth without any patterned structure. This temperature-ramping technique, gives crack-free high-quality 2"-diameter GaN films, thicker than 250 mu m, on sapphires in high yields. These thick GaN films can be separated from sapphire using conventional laser-induced lift-off processes, which can be followed by subsequent HVPE regrowths. A 600 mu m-thick free-standing GaN films has a typical dislocation density of around 4x10(6) cm(-2) with a full width at half maximum (FWHM) in the high resolution X-ray diffraction (HRXRD) spectrum of GaN (002) of around 150 arcsec. The residual stress in the thick GaN films was analyzed by micro-Raman spectroscopy. The effectiveness of the patterning and the non-patterning techniques in reducing the strain in GaN films is discussed. The advantages and weaknesses of the patterning and the non-patterning techniques will be elucidated.
URI: http://hdl.handle.net/11536/13056
http://dx.doi.org/10.1117/12.814441
ISBN: 978-0-8194-7477-3
ISSN: 0277-786X
DOI: 10.1117/12.814441
期刊: LIGHT-EMITTING DIODES: MATERIALS, DEVICES, AND APPLICATIONS FOR SOLID STATE LIGHTING XIII
Volume: 7231
顯示於類別:會議論文


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