Light-intensity dependence of excess carrier lifetimes

It has been widely assumed that measured photoconductivity response times do correspond to photocarrier recombination lifetimes. Such an assumption is shown to lead to the conclusion that, if true, the light-intensity dependence of the photoconductivity and of the response time, sigma(ph) proportional to G(gamma) and tau(d) proportional to G(-beta), should be governed by the same exponent, i.e., gamma = beta would be required. Since this is often not seen experimentally, a simple theory is developed that can account for the difference by explicitly introducing a small recombination probability in the general multiple-trapping formalism,