High quality free-standing GaN thick-films prepared by hydride vapor phase epitaxy using stress reducing techniques

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

doi:10.1117/12.814441

3 February 2009 High quality free-standing GaN thick-films prepared by hydride vapor phase epitaxy using stress reducing techniques

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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Proceedings Volume 7231, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XIII; 723116 (2009) https://doi.org/10.1117/12.814441
Event: SPIE OPTO: Integrated Optoelectronic Devices, 2009, San Jose, California, United States

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.

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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, and Li-Wei Tu "High quality free-standing GaN thick-films prepared by hydride vapor phase epitaxy using stress reducing techniques", Proc. SPIE 7231, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XIII, 723116 (3 February 2009); https://doi.org/10.1117/12.814441

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KEYWORDS

Gallium nitride

Sapphire

Raman spectroscopy

Semiconducting wafers

Scanning electron microscopy

Optical lithography

Micro raman spectroscopy

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