Modeling of processes of charge separation in a GaAs detector

The problem of charge separation in a GaAs detector has been solved by means of mathematical modeling. Dynamics of the process for a three-dimensional detector is described in this work in detail. It is shown that in case of interaction with alpha particles, the plasma time can reach several nanoseconds in a strong electric field. In a weak electric field the plasma time exceeds the charge carrier lifetime. The time of separation of charge carriers created by a gamma photon in a strong electric field is 100 ps. The results of calculation are confirmed by experimental data.