Deep UV laser etching of GaN epilayers grown on sapphire substrate

The laser etching of GaN epilayers on sapphire substrate was carried out using a deep ultraviolet pulsed laser (157 nm wavelength, 20 ns pulse width). The quality and morphology of the etched GaN surface were evaluated by scanning electron microscopy, atomic force microscopy and scanning profilomete...

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Bibliographic Details
Published in:Journal of materials processing technology 2012-02, Vol.212 (2), p.492-496
Main Authors: Dai, Yu-Tang, Xu, Gang, Tong, Xin-Lin
Format: Article
Language:English
Subjects:
157 nm laser
Etching
Gallium nitrides
GaN epilayers
Heat affected zone
Laser etching
Lasers
Micro-structure
Pulse width
Sapphire
Sapphire substrate
Scanning electron microscopy
Surface roughness
Ultraviolet
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Summary:The laser etching of GaN epilayers on sapphire substrate was carried out using a deep ultraviolet pulsed laser (157 nm wavelength, 20 ns pulse width). The quality and morphology of the etched GaN surface were evaluated by scanning electron microscopy, atomic force microscopy and scanning profilometer. Quadrate micro-hole and micro-trenches etched by the 157 nm laser exhibited clean and smooth edges, sharp side walls and very small heat affected zone (HAZ). In order to achieve controllable high-quality etching, the laser and processing parameters, such as laser repetition rate, scan speed, were systematically investigated and optimized. The mechanism analysis shows that, direct photoionization or photo-chemical reaction play predominant role within 157 nm laser etching of GaN epilayers.
ISSN:0924-0136
DOI:10.1016/j.jmatprotec.2011.08.022