Analysis of material modifications caused by nanosecond pulsed UV laser processing of SiC and GaN |
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Authors: | Olaf Krüger Tim Wernicke Joachim Würfl Roland Hergenröder Günther Tränkle |
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Institution: | 1.Ferdinand-Braun-Institut für H?chstfrequenztechnik,Berlin,Germany;2.ISAS-Institute for Analytical Sciences,Dortmund,Germany |
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Abstract: | The effects of direct UV laser processing on single crystal SiC in ambient air were investigated by cross-sectional transmission
electron microscopy, Auger electron spectroscopy, and measurements of the electrical resistance using the transfer length
method (TLM). Scanning electron microscopy was applied to study the morphology and dimensions of the laser-treated regions.
After laser processing using a nanosecond pulsed solid-state laser the debris consisting of silicon oxide was removed by etching
in buffered hydrofluoric acid. A layer of resolidified material remains at the surface indicating the thermal impact of the
laser process. The Si/C ratio is significantly disturbed at the surface of the resolidified layer and approaches unity in
a depth of several tens of nanometers. A privileged oxidation of carbon leaves elementary resolidified silicon at the surface,
where nanocrystalline silicon was detected. Oxygen and nitrogen were detected near the surface down to a depth of some tens
of nanometers. A conductive surface film is formed, which is attributed to the thermal impact causing the formation of the
silicon–rich surface layer and the incorporation of nitrogen as dopant. No indications for microcrack or defect formation
were found beneath the layer of resolidified material. |
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Keywords: | PACS" target="_blank">PACS 68 37 Lp 79 20 Ds 81 40 -z 81 70 Jb |
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