Intensity modulated photocurrent spectroscopy (IMPS) was used to study the kinetics of recombination processes at n‐type silicon surfaces in 0.1 M solution at pH 9. Recombination dominates the photocurrent‐potential curve at potentials up to 0.5 V positive with respect to the flatband potential in the dark. Complex plane representations of the IMPS results shows almost perfect semicircles over a large potential range, indicating that surface recombination is governed by a single time constant process. The potential dependence and light intensity dependence of the recombination time constant were studied in detail. We show that a model which incorporates the modulation of the potential drop across the Helmholtz layer, resulting from the modulated occupancy of the recombination centers, explains the IMPS results. From the results, the capacitance of the Helmholtz layer could be determined to be about . The recombination rate constant was found to be about , which is in good agreement with results from electrochemical impedance measurements.
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Oskam et al. (1996) studied this question.