Abstract

Far Infrared Terahertz spectroscopy unambiguously demonstrates sub-picosecond electron lifetimes in low-temperature-grown GaAs. A systematic study of as-grown and annealed, low-temperature-grown GaAs, reveals carrier lifetimes to be directly related to the excess arsenic incorporation and anneal conditions. The observation of subpicosecond lifetimes is attributed to the far infrared interaction and dilute photoexcitation densities. A simple rate equation model is developed to interpret the results and to determine the relative electron mobility. Additionally, Drude-like behavior of the free carrier conductivity within 1 ps of excitation is revealed using time resolved differential spectroscopy.

© 1997 Optical Society of America