PHOTOINDUCED INTERSUBBAND ABSORPTION IN NORMAL-DOPED QUANTUM-WELLS

We report on the study of Si-doped GaAs/AlGaAs narrow multiquantum wells (MQWs) using the intersubband photoinduced absorption technique. For the barrier-doped MQWs, we find that an impurity level which is approximately 60 meV below the barrier band gap, causes a photoinduced reduction ("bleaching") in the e1-e2 intersubband absorption. This is not observed for the MQWs doped in the well. For a Si-doped level of approximately 2.5 X 10(16) cm-3 (in the barriers), we estimate the density of the impurities causing the bleaching to be of the order of 2 X 10(8) cm-2 per barrier.