Phonoconductivity measurements of the electron-phonon interaction in quantum wire structures

Abstract

Abstract We have used a phonoconductivity technique to investigate the electron-phonon interaction in quantum wires. This interaction has important consequences for certain aspects of device behaviour. The 10 μm long wires were formed in GaAs/AlGaAs heterojunctions using split-gates. Ballistic phonon pulses, with an approximately Planckian frequency spectrum, were generated by a resistive film heater on the opposite side of the substrate. The interaction of the phonons with the quantum wire was detected via changes in conductance of the device. Oscillations in the phonoconductivity were observed with increasing (negative) gate bias. These oscillations were related to the Fermi level position relative to the one-dimensional subband structure which was determined from electrical transport measurements. We give a qualitative explanation of the results in terms of phonon induced inter- and intra- 1D subband electronic transitions leading to changes in the electron temperature which in turn affect the conductance. From our results we obtain a value for the effective width of the quantum wire.