In this study, the suitability of Tauc-Lorentz and Gaussian oscillator models to describe amorphous silicon-carbon alloys of various compositions was tested. The dependence of the model parameters on the composition showed that the amplitude and broadening of both oscillators behave similarly and significant differences can only be observed in the oscillators' position in case of high broadening parameter values. It was shown that this difference originates from the different mathematical forms of the oscillators and from the high broadening values. Sensitivity analysis of the parameters showed that the models became less sensitive to their parameters with large broadening values. Furthermore the model parameters were correlated to the various types of chemical bonding present within the samples. (C) 2011 Elsevier B.V. All rights reserved.