Intersubband Tunneling without Intrasubband Relaxation in Multi-quantum Wells

摘要

We present evidence of a new photon-assisted tunneling channel in multi-quantum wells in the presence of a magnetic field applied parallel to the quantum well layers. Electrons in one potential well that are photo-excited to anti-crossings of the dispersion curves of the conduction subbands tunnel resonantly to the neighboring well without intrasubband relaxation. This tunneling mechanism is to be distinguished from tunneling involving states located around the energy minimum of the conduction subbands. Measurements of the photocurrent under THz illumination show that both tunneling processes co-exist in a GaAs/AlGaAs multi-quantum well superlattice.