OSCILLATORY AND MAGNETO-OSCILLATORY STRUCTURE OF THE TUNNEL CURRENT IN DOUBLE-BARRIER HETEROSTRUCTURES

We investigated the current-voltage I(V) characteristics of GaAs/AlAs double-barrier heterostructures. A fine periodic structure of the reso nant tunnel current has been revealed. We attribute it to a sequence o f the collective excitations, presumably of the coupled plasmon-phonon type, that are induced in the heavily doped collector region by hot e lectrons which escape from the quantum well. An oscillatory structure appears also in the valley regions of the I(V) curve under a high magn etic field parallel to the current. It is due to the off-resonance tun nelling between the Landau-quantized states of the emitter and quantum well. Particular phonon-assisted processes in the tunnelling have bee n identified.