Optical Phonon-Assisted Tunneling in Double Quantum-Well Structures

Abstract
Using subpicosecond time-resolved luminescence spectroscopy, we have investigated tunneling of electrons in a double quantum well structure. The sample is a p-i-n diode, which contains two GaAs quantum wells of different thicknesses separated by a 55 Å Al0.65Ga0.35As barrier layer. We observe a large increase of the tunneling rates when the two lowest energy subbands of the coupled wells are separated by more than an optical phonon energy. These results demonstrate that phonon-assisted tunneling play a significant role in this structure and in the carrier transport of related multiple quantum well structures.