DRAMATIC PHOTOINDUCTION OF HOLE TUNNELING IN DOUBLE-QUANTUM WELLS WITH BUILT-IN PIEZOELECTRIC FIELDS

We show that efficient tunneling of holes can be produced in double qu antum wells with built-in piezoelectric fields by the photoscreening o f that piezoelectric field. Our observation was made at low temperatur es by comparing the behavior of Ga0.92In0.08As-GaAs strained-layer dou ble quantum wells grown along the (111) and (001) directions and tunin g the densities of photoinjected carriers over several decades. Interp retation of the experimental data is made by comparison with Hartree c alculations including the space charge effects. In addition to this, w e also report the observation of many-body interactions at high photoc arrier densities.