Hole trapping time measurement in low-temperature-grown gallium arsenide

We study hole dynamics in GaAs layers grown by molecular-beam epitaxy at 270 deg. C by two-color pump-and-probe experiments employing femtosecond 800-nm-wavelength pulses for sample's excitation and 9-μm-wavelength pulses for probing the induced intervalence band absorption. Hole trapping time in as-grown, undoped layer is equal to 2 ps; it increases after thermal annealing or Be doping, and decreases in Si-doped layer. The mechanism of the hole trapping is discussed; it is shown that experimental observations are consistent with the hole trapping at neutral arsenic antisites model