Regensburg 2004 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 22: Postersitzung

DS 22.53: Poster

Dienstag, 9. März 2004, 14:30–17:00, Poster B

Influence of the substrate preparation on the low-temperature epitaxy of Si by electron-cyclotron resonance chemical vapor deposition — •Patrick Clemens, Björn Rau, Ina Sieber, Stefan Gall, and Walther Fuhs — Hahn-Meitner-Institut, Abt. Silizium Photovoltaik, Kekuléstr. 5, D-12489 Berlin

We report on a study of substrate preparation for the low-temperature Si homo-epitaxy by electron-cyclotron resonance chemical vapor deposition (ECRCVD). The background of the research is the development of a low-temperature epitaxial thickening process for Si thin-film solar cells on large-grained polycrystalline Si seed layers on glass.

Different from conventional high-temperature Si deposition methods the conditions of the substrate surface, its crystal orientation and its contamination are very critical for the successful epitaxial growth of Si at substrate temperatures below 600 ^∘C. Both, wet chemical surface pre-treatments and in-situ treatments are applied to obtain an ideal substrate surface for Si epitaxy. Using a HF/alcohol instead of HF/water solution the roughness of the surface of Si wafers decreases, the surface contaminations are reduced, and the H-termination of the Si surface is improved. During substrate heating in-situ H-treatment is used to increase the stability of this surface and prevent reoxidation. This substrate preparation leads to a successful epitaxial growth of Si on Si(100) wafers at low temperatures. The influence of the preparation on the Si epitaxy is analyzed by structural and electrical characterizations of the grown films.