Numerical study of the effect of surface recombination on nonlinear and phase distortions arising during the restoration of the optical signal shape

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