Photoinduced intersubband absorption in n-doped quantum wells

Abstract

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 thatan impurity level which is ∼ 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 ∼ 2.5 ×1016 cm−3 (in the barriers), we estimate the density of the impurities causing the bleaching to be of the order of 2 ×108 cm−2 per barrier.