PICOSECOND CARRIER ESCAPE BY RESONANT-TUNNELING IN PSEUDOMORPHIC INGAAS GAASP QUANTUM-WELL MODULATORS/

We have used time-resolved transmission and photocurrent measurements at 1.06 mum to study carrier sweepout in strain-relaxed InGaAs/GaAs an d strain-balanced lnGaAs/GaAsP quantum well modulators. Our results sh ow carrier sweepout on a picosecond time scale from both structures, i n agreement with the high saturation intensities measured for these de vices. Carrier escape from the InGaAs/GaAs structure is facilitated by a low band offset and occurs in tens of picoseconds even without exte rnal bias. In the InGaAs/GaAsP structure, which has a much larger band offset, resonant tunneling reduces the sweepout time from 1.8 ns at z ero bias to 10 ps at -6 V.