ULTRAFAST DYNAMICS OF NONLINEAR ABSORPTION IN LOW-TEMPERATURE-GROWN GAAS

We present the results of a study of the subpicosecond dynamic behavio r of optically induced absorption changes in low-temperature-grown GaA s. We show that the observed behavior is dominated by mid-gap trap sta tes, and can be accurately modeled by the rate equations previously de veloped to describe quasi-cw results. Our data give the first approxim ate values for trap emptying times in this material. (C) 1996 American Institute of Physics.