The photoconductivity kinetics of a resistor with homogeneous generation of electrons and holes in thickness is investigated. Calculations are carried out for an n-type semiconductor. The cases of linear and quadratic volumetric recombination are considered. The mathematical model of the process includes a non-linear parabolic partial differential equation. The cause of its non-linearity is quadratic recombination. Boundary conditions of the 3rd kind are used, thus allowing to examine the surface recombination of nonequilibrium charge carriers. This latter phenomenon makes it necessary to take into account the diffusion term when writing kinetic equations describing the distribution of electrons and holes. The model neglects the volumetric charge. In described circumstances it is possible to use the integration of the photocurrent flowing through the resistor to obtain the dependence of the light intensity on time for small optical pulse durations: T<max(τn,τp). Here T is the pulse duration, τn and τp are the lifetimes of electrons and holes, respectively. Nonlinear distortions in this case are mainly associated with the appearance of the second and the third harmonics of the Fourier series expansion of the function that determines the photocurrent dependence on time. To "restore" the optical pulse, the operation of differentiating the photocurrent can be used. Nonlinear and phase distortions are small when the condition T<max(τn,τp) is met. Proposed methods make it possible to expand the range of optical pulse durations (T) in which its "recovery" is possible. In the vicinity of the region defined by the equality T≈max(τn,τp), nonlinear and phase distortions are significant.

The kinetics of silicon photoconductivity with recombination centers of gold is investigated. If the frequency of light intensity modulation is less than the inverse value of the main charge carriers’ lifetime, the functions describing the dependence of light intensity on time and the dependence of the photocurrent on time agree within some factor. At high frequencies of modulation of light intensity distortions arise. The dependences of light intensity on time and photocurrent on time become different. In this case, the effect of the recombination rate on the function of the variable component of the photocurrent is not significant. Basically, this function is determined by the dependence of the generation rate on time. At high frequencies, it is possible to "restore" the shape of the optical pulse using the electric pulse of the photoresistor. The dependences on the frequency of phase, linear and nonlinear distortions arising in the "restoration" of the dependence of the light intensity on time are obtained. The results are given for different values of the rate of charge carrier generation.