Mechanisms influencing {open_quotes}hot-wire{close_quotes} deposition of hydrogenated amorphous silicon
- National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
- JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 (United States)
Intrinsic hydrogenated amorphous silicon (a-Si:H) has been deposited using a hot tungsten filament in pure silane to drive the deposition chemistry{emdash}the {open_quotes}hot-wire{close_quotes} deposition method. The electronic and infrared properties of the film have been measured as a function of deposition parameters, leading to three principal conclusions. First, to obtain a high quality material, the Si atoms evaporated from the filament (distance L from the substrate) must react with silane (density n{sub s}) before reaching the substrate; this requires n{sub s}L greater than a critical value. Second, radical-radical reactions cause deterioration of film properties at high values of G(n{sub s}L),{sup 3} where G is the film growth rate; this requires G(n{sub s}L){sup 3} less than a critical value. Finally, the film quality is a function of G, and as G is increased the substrate temperature must be correspondingly increased to obtain high film quality. By optimizing these parameters, we have produced films with excellent electronic properties (e.g., ambipolar diffusion length {gt}200 nm) at {gt}5 nm/s deposition rate. Based on these insights, formulas are also given for optimizing film properties in multiple-filament geometries and in diluted silane. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 527989
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 4 Vol. 82; ISSN JAPIAU; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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