THEORETICAL-ANALYSIS OF THE LASER-INDUCED PHOTOTRANSIENT RESPONSE OF SEMICONDUCTOR ELECTROLYTE CIRCUITS WITH CURRENT-DOUBLING REACTIONS

A model describing the phototransient response of a semiconductor \ el ectrolyte junction to a short laser pulse in case of ''current-doublin g'' reactions is proposed. The rate constants of a charge transfer acr oss the Helmholtz layer, the recombination of carriers and injection o f majority carriers from intermediates in the solution back to the sem iconductor are introduced in this model. The analysis is restricted by consideration of a low intensity pulse which enables perturbation cau sed by illumination to be neglected, and second-order processes such a s the capture of the second minority carrier by the reactive intermedi ate which can take place under strong light illumination can be ignore d. A general equation describing the phototransient response in the fr ame of a simple linear model is obtained, and different cases in photo potential and photocurrent measurements are considered. Analysis of ph ototransient data in the case of current-doubling reactions allows the rate constants of charge transfer at the semiconductor \ electrolyte interface to be estimated directly.