A numerical Kramers-Kronig analysis is used to predict the refractive-index perturbations produced in crystalline silicon by applied electric fields or by charge carriers. Results are obtained over the 1.0-2.0 pm optical wavelength range. The analysis makes use of experimental electroabsorption spectra and impurity-doping spectra taken from the literature. For electrorefraction at the indirect gap, we find An = 1.3 X lo5 at X = 1.07 pm when E = lo5 V/cm, while the Kerr effect gives An = at that

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... field strength. The charge-carrier effects are larger, and a depletion or injection of 10" carriers/cm3 produces an index change of k1.5 X at X = 1.3 pm. G