PHONOCONDUCTIVITY MEASUREMENTS OF THE ELECTRON-PHONON INTERACTION IN QUANTUM-WIRE STRUCTURES

We have used a phonoconductivity technique to investigate the electron -phonon interaction in quantum wires. This interaction has important c onsequences for certain aspects of device behaviour. The 10 mu m long wires were formed in GaAs/AlGaAs heterojunctions using split-gates. Ba llistic phonon pubes, with an approximately Planckian frequency spectr um, were generated by a resistive film heater on the opposite side oi the substrate. The interaction of the phonons with the quantum wire wa s detected via changes in conductance of the device. Oscillations in t he phonoconductivity were observed with increasing (negative) gate bia s. These oscillations were related to the Fermi level position relativ e to the one-dimensional subband structure which was determined from e lectrical transport measurements. We give a qualitative explanation of the results in terms of phonon induced inter- and intra- 1D subband e lectronic transitions leading to changes in the electron temperature w hich in turn affect the conductance. From our results we obtain a valu e for the effective width of the quantum wire.