OBSERVATION OF GIANT OSCILLATIONS IN THE PHONON-INDUCED CONDUCTIVITY OF A GAAS QUANTUM-WIRE

We have made phonon measurements of the electron-phonon interaction in a long quantum wire using the phonoconductivity technique. The wire w as formed in a GaAs/AlxGa1-xAs heterojunction using the split-gate met hod. It was subjected to a pulsed beam of nonequilibrium phonons gener ated by a heater on the opposite side of the substrate. The incident p honon pulses caused a transient increase in the device conductance. Th e strength of the detected signal displayed giant oscillations as the wire was narrowed by increasing the negative bias on the gate. We give a qualitative account of these observations in terms of phonon-induce d delocalization of weakly localized electron states in the wire.