Fast Recovery from Excitonic Absorption Bleaching in Type-II GaAs/AlGaAs/AlAs Tunneling Biquantum Well

Abstract
We propose the type-II tunneling biquantum-well (TBQ) structure which consists of a series of GaAs wells, AlGaAs barriers and AlAs layers. The type-II TBQ has no significant optical absorption except for the GaAs wells and shows fast recovery from excitonic absorption bleaching. In this structure, photoexcited electrons in the GaAs wells escape by tunneling through the AlGaAs barriers toward X states in the AlAs layers. The recovery time of excitonic absorption bleaching in the GaAs wells was reduced to 8 ps as the AlGaAs barrier thickness was decreased to 1.1 nm.