SWEEP-OUT TIMES OF ELECTRONS AND HOLES IN AN INGAAS GAAS MULTIPLE-QUANTUM-WELL MODULATOR/

The switch-on and switch-off times of a p-i-n diode containing In0.13G a0.87As/GaAs multiple quantum wells in the i region have been characte rized by a time-resolved pump/probe technique. We observe bias-insensi tive switch-on times and dramatically increasing switch-off times with decreasing bias. We use a simple model invoking the cross-well motion of holes as well as electrons to explain the experimental result. The effective drift velocities of both electrons and holes across the mul tiple quantum wells at different bias voltages are deduced from this m odel.