Longitudinal-optical-phonon assisted tunneling in tunneling bi-quantum well structures

We discuss the electron tunneling time observed in a new AlGaAs/GaAs superlattice structure, the tunneling bi-quantum well (TBQ). To calculate the nonresonant tunneling time, we made experiments on resonant tunneling to confirm that the 60% rule of conduction-band discontinuity accurately evaluates the free tunneling probability of electrons. We found that the observed recovery time agrees quite well with the calculated longitudinal optical phonon emission tunneling time for thin (≤ 10 monolayers) barriers.