Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 69: Nitrides: LEDs

HL 69.3: Vortrag

Donnerstag, 17. März 2011, 10:45–11:00, POT 51

Micromachining with picosecond laser pulses: A versatile tool for the fabrication of optoelectronic devices — •Rüdiger Moser, Michael Kunzer, Christian Goßler, Klaus Köhler, Ulrich Schwarz, and Joachim Wagner — Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastrasse 72, D-79108 Freiburg, Germany

Picosecond (ps) lasers provide a universal tool for material processing. Due to the short laser pulses material is removed by a process called "cold ablation", with minimal thermal damage to neighbour regions. As a result, better defined structures with smother and cleaner side walls can be fabricated than with "long-pulse" lasers. This offers new possibilities for laser processing in semiconductor technology for both semiconductor materials and contact or bond metallizations. The fabrication of semiconductor devices typically requires lithography steps, which are time consuming and expensive. Therefore one would like to avoid these steps at least for development and prototyping. One way to do so is to replace lithography steps by direct laser writing. In this presentation we report on the development of ps laser processes to directly pattern the semiconductor surface with trenches and mesas for the fabrication of GaN-based LEDs. The laser processed devices are electrically and optically characterised and compared with conventionally fabricated test devices. Furthermore the realization and use of high quality shadow masks for e.g. deposition of ohmic contact metallizations is reported and compared with results obtained using nanosecond laser processing.