Time resolved measurements of cross-well transport in a multiple quantum well p-i-n modulator at high photogenerated carrier densities

Carrier sweep-out rates from GaAs/AlGaAs multiple quantum wells have been measured as a function of excitation level on picosecond time scales at different values of applied electric field. A minimum rate of ∼20 ps was observed under resonant tunneling conditions at low generated carrier densities. At higher excitation levels, the effects of space charge build-up were found to significantly alter the transient nonlinear optical response due to changes in the time constant associated with vertical carrier transport.