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Title: Gap state distribution in amorphous hydrogenated silicon carbide films deduced from photothermal deflection spectroscopy
Authors: Chew, K.
Yoon, S.F.
Ahn, J.
Zhang, Q.
Ligatchev, V.
Teo, E.J. 
Osipowicz, T. 
Watt, F. 
Issue Date: 1-Apr-2002
Citation: Chew, K., Rusli, Yoon, S.F., Ahn, J., Zhang, Q., Ligatchev, V., Teo, E.J., Osipowicz, T., Watt, F. (2002-04-01). Gap state distribution in amorphous hydrogenated silicon carbide films deduced from photothermal deflection spectroscopy. Journal of Applied Physics 91 (7) : 4319-4325. ScholarBank@NUS Repository.
Abstract: The density of gap states distribution in silicon (Si) rich hydrogenated amorphous silicon carbide (a-Si 1-xC x:H) films with varying carbon (C) fraction (x) is investigated by the photothermal deflection spectroscopy (PDS). The films are grown using the Electron Cyclotron Resonance Chemical Vapor Deposition (ECR-CVD) technique. By using different methane-to-silane gas flow ratios, a-Si 1-xC x:H with x ranging from 0 to 0.36 are obtained. A deconvolution procedure is performed based on a proposed DOS model for these Si rich a-Si 1-xC x:H. Good fits between the simulated and experimental spectra are achieved, thus rendering support to the model proposed. Deduction of the DOS enables us to obtain various parameters, including the optical gap and the valence band tail width. The fitted mobility gap E g is found to be well correlated to the Tauc gap E tauc and E 04 gap deduced from the optical absorption spectra. A correlation is also seen between the fitted valence band tail width E vu, the Urbach energy E u and the defect density. All these parameters are seen to increase with C alloying. A shift in the defect energy level in the midgap with increasing C incorporation is observed, together with a broadening of the defect distribution and a stronger correlation between the defect bands, which can be accounted for in terms of the influence of C dangling bonds on the deep defect density distribution. © 2002 American Institute of Physics. © 2002 American Institute of Physics.
Source Title: Journal of Applied Physics
ISSN: 00218979
DOI: 10.1063/1.1448888
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