Time-resolved differential reflection measurements on Ga1-xMnxAs

Abstract

We measured the time-resolved differential reflectivity, Delta R, of Ga1-xMnxAs for x <= 0.05 for various excitation wavelengths and compared with the signals from semi-insulating GaAs substrates. The sign of AR from Ga1-xMnxAs (x = 0.015 and x = 0.03) was negative at 295 K for photon energies larger than bandgap, which was ascribed to defect-induced absorption or a reduction of exciton bleaching. We also discuss the screening of Mn alloy potential fluctuations by photocarriers in the time-resolved differential reflection of Ga1-xMnxAs