The effect of hydrogen dilution on the hot-wire deposition of microcrystalline silicon
- Univ. Stuttgart (Germany). Inst. fuer Physikalische Elektronik
The HWCVD technique is a very promising method for solar cell or thin film transistor (TFT) applications. The growth of amorphous (a-Si:H) and microcrystalline ({micro}c-Si) silicon by hot-wire chemical vapor deposition (HWCVD) has been studied by combining in-situ ellipsometry, atomic force microscopy (AFM), and Raman spectroscopy. Generally a dense nucleation layer is formed during a-Si:H HWCVD, containing nuclei about 0.8 nm high and 10 to 20 nm in diameter. The surface roughness gradually increases with film thickness and settles at a root mean square (RMS) value of 1.6 nm at about 200 nm thickness. For hydrogen dilution at gas flow ratios x = [H{sub 2}]/[SiH{sub 4}] of 15 to 120 microcrystalline material was obtained. The grain size and nucleation layer, however, are strongly dependent on x. Low H{sub 2} dilution enhances the formation of an amorphous-like interface layer from which the {micro}c-Si:H growth eventually starts. Increasing x promotes the etching of amorphous regions and the surface diffusion of precursors, resulting in larger nuclei. x = 30 yields extended {micro}c-Si nuclei (30 nm height, 90 nm diameter) and a pronounced increase in surface roughness for thicker films, but suppresses the formation of the amorphous-like nucleation layer. A further increase in x remarkably lowers the growth rate, but smoother surfaces at comparable film thickness and larger lateral dimensions of the grains occur. This is interpreted as incipient etching of the crystallites.
- OSTI ID:
- 527648
- Report Number(s):
- CONF-960401-; ISBN 1-55899-323-1; TRN: IM9741%%76
- Resource Relation:
- Conference: Spring meeting of the Materials Research Society (MRS), San Francisco, CA (United States), 8-12 Apr 1996; Other Information: PBD: 1996; Related Information: Is Part Of Amorphous silicon technology -- 1996; Hack, M. [ed.] [dpiX, Palo Alto, CA (United States)]; Schiff, E.A. [ed.] [Syracuse Univ., NY (United States)]; Wagner, S. [ed.] [Princeton Univ., NJ (United States)]; Schropp, R. [ed.] [Utrecht Univ. (Netherlands)]; Matsuda, Akihisa [ed.] [Electrotechnical Lab., Tsukuba (Japan)]; PB: 929 p.; Materials Research Society symposium proceedings, Volume 420
- Country of Publication:
- United States
- Language:
- English
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