TRANSIENT NEGATIVE PHOTOCONDUCTANCE IN A CHARGE-TRANSFER DOUBLE-QUANTUM-WELL UNDER OPTICAL INTERSUBBAND EXCITATION

Recently, it was shown that an electron-hole radiative recombination i s induced by a mid-infrared light exciting an intersubband transition in a charge transfer double quantum well (CTDQW). This recombination w as attributed to an upstream transfer of electrons from an electron-ri ch well to a hole-rich well. In this study, we investigated the electr ical response of a CTDQW under intersubband optical excitation, and fo und that a positive photocurrent. opposite in sign and proportional to the applied electric field, accompanies the intersubband-transition-i nduced luminescence (ITIL) signal. A negative photocurrent component w as also observed and attributed to heating processes. This work brings a further evidence of the ITIL process and shows that an important pr oportion of the carriers are consumed by the transfer of electrons. (C ) 1998 Elsevier Science B.V. All rights reserved.