CARRIER NONRESONANT TUNNELING IN ASYMMETRIC COUPLED DOUBLE QUANTUM-WELLS

The excitation power dependence of nonresonant tunneling rates for photogenerated carriers is studied in a GaAs/Al0.35Ga0.65As/GaAs (50A/40A/100A) asymmetric double quantum well p-i-n structure by photoluminescence (PL) measurement. It is found that PL from the two coupled wells depends strongly on excitation power. Especially, the PL peak intensity of the narrow well rapidly decreases as excitation power increases to a certain extent. The explanation for the strong excitation power dependence of the carrier tunneling rates is that LO-phonon-assisted tunneling enhances the rates significantly because of energy-band flattening due to the spatial separation of electrons and holes between the two coupled wells. Our results may be of significance in creating novel alloptical devices. © 1992.