Time-resolved cavity ringdown study of the Si and SiH{sub 3} surface reaction probability during plasma deposition of a-Si:H at different substrate temperatures
Time-resolved cavity ringdown spectroscopy ({tau}-CRDS) has been applied to determine the surface reaction probability {beta} of Si and SiH{sub 3} radicals during plasma deposition of hydrogenated amorphous silicon (a-Si:H). In an innovative approach, our remote Ar-H{sub 2}-SiH{sub 4} plasma is modulated by applying pulsed rf power to the substrate and the resulting time-dependent radical densities are monitored to yield the radical loss rates. It is demonstrated that the loss rates obtained with this {tau}-CRDS technique equal the loss rates in the undisturbed plasma and the determination of the gas phase reaction rates of Si and SiH{sub 3} as well as their surface reaction probability {beta} is discussed in detail. It is shown that Si is mainly lost in the gas phase to SiH{sub 4} [reaction rate k{sub r}=(3.0{+-}0.6)x10{sup -16} m{sup 3}s{sup -1}], while the probability for Si to react at an a-Si:H surface is 0.95<{beta}{sub Si}<1 for a substrate temperature of 200 deg. C. SiH{sub 3} is only lost in reactions with the surface and measurements of {beta} of SiH{sub 3} for substrate temperatures in the range of 50-450 deg. C show that {beta}{sub SiH{sub }}3=(0.30{+-}0.03), independent of the substrate temperature. The implications for a-Si:H film growth are discussed.
- OSTI ID:
- 20662099
- Journal Information:
- Journal of Applied Physics, Vol. 96, Issue 8; Other Information: DOI: 10.1063/1.1793359; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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