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Proceedings Paper

High quality free-standing GaN thick-films prepared by hydride vapor phase epitaxy using stress reducing techniques
Author(s): Hsin-Hsiung Huang; Wei-I Lee; Kuei-Ming Chen; Ting-Li Chu; Pei-Lun Wu; Hung-Wei Yu; Po-Chun Liu; Chu-Li Chao; Tung-Wei Chi; Jenq-Dar Tsay; Li-Wei Tu
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Paper Abstract

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 μm, 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 μm-thick free-standing GaN films has a typical dislocation density of around 4×106 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.

Paper Details

Date Published: 3 February 2009
PDF: 14 pages
Proc. SPIE 7231, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XIII, 723116 (3 February 2009); doi: 10.1117/12.814441
Show Author Affiliations
Hsin-Hsiung Huang, National Chiao Tung Univ. (Taiwan)
Wei-I Lee, National Chiao Tung Univ. (Taiwan)
Kuei-Ming Chen, National Chiao Tung Univ. (Taiwan)
Industrial Technology Research Institute (Taiwan)
Ting-Li Chu, National Chiao Tung Univ. (Taiwan)
Pei-Lun Wu, National Chiao Tung Univ. (Taiwan)
Hung-Wei Yu, National Chiao Tung Univ. (Taiwan)
Po-Chun Liu, Industrial Technology Research Institute (Taiwan)
Chu-Li Chao, Industrial Technology Research Institute (Taiwan)
Tung-Wei Chi, Industrial Technology Research Institute (Taiwan)
Jenq-Dar Tsay, Industrial Technology Research Institute (Taiwan)
Li-Wei Tu, National Sun Yat-Sen Univ. (Taiwan)

Published in SPIE Proceedings Vol. 7231:
Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XIII
Klaus P. Streubel; Heonsu Jeon; Li-Wei Tu, Editor(s)

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