Temporal dynamics of impurity photoconductivity in $n$-GaAs and $n$-InP

The dynamics of impurity photoconductivity in $n$-GaAs and $n$-InP under photoexcitation with a short light pulse has been calculated. It has been shown that the photoconductivity dynamics in a nanosecond time range is determined by cooling of electrons, while the role of cascade capture of electrons by impurity is insignificant in this range. A nonmonotonic time dependence of photoconductivity caused by the competition between different relaxation mechanisms of the electron pulse has been predicted.