The dynamics of shallow donor ionization in n-GaAs studied with subnanosecond FIR-induced photoconductivity

The low-temperature dynamics of far-infrared (FIR) excited electrons bound to shallow donors has been studied in n-GaAs. In a magnetic field of 3.6 T the electrons are excited from the ground state to the 2p +1 donor state with a short pulse of 118.8 mu m radiation and the photoconductive response is monitored with subnanosecond resolution. The observed response can be described with a simple three-level rate equation model, yielding a minimum value of 5*10 9 s -1 for the ionization rate of a shallow donor in the 2p +1 bound state.