Separation of electron and hole dynamics in low-temperature grown GaAs

Electron and hole recombination in beryllium doped low-temperature grown GaAs is investigated by two-color pump-probe experiments. Depending on the charge state of the arsenic antisite defects, a 0.9 eV sub-bandgap pump pulse selectively promotes electrons or holes to the conduction or valence band, respectively. The doping level and growth temperature determine the charge state. Holes from singly ionized antisites recombine within a few ps. Recombination of holes from doubly ionized antisites and of electrons from neutral antisites takes place on a 100 ps time scale. Most likely, electrons from neutral antisites are captured by a different type of defect and slowly recombine afterwards