Energy-loss rate of a two-dimensional electron gas measured using a mesoscopic thermometer

Abstract

Using a simple setup, the linear thermopower is measured in etched one-dimensional (1D) constrictions with large subband energy spacings, allowing the temperature of the two-dimensional electron gas on one side of the constriction to be determined as a function of the applied heating power. As tested by the Cutler-Mott relation, the 1D constriction acts as a reliable electron thermometer for lattice temperatures in the range TL=4.2-13 K. The power dissipated per electron, measured as a function of electron temperature, reveals that at TL=4.2 K the acoustic phonon scattering is dominated by T5 behavior due to an unscreened deformation potential. At higher lattice temperatures the scattering can be described by an interpolation between the Gruneisen-Bloch and equipartition regimes.