Heat flow, transport and fluctuations in etched semiconductor quantum wire structures

Low-dimensional transport in semiconductor meso-and nanostructures is a topical field of fundamental research with potential applications in future quantum devices. However, thermal non-equilibrium may destroy phase-coherence and remains to be explored experimentally. Here, we present effects of thermal non-equilibrium in various implementations of low-dimensional (non-interacting) electron systems, fabricated by etching AlGaAs/GaAs heterostructures. These include narrow quasi-two-dimensional (2D) channels, quasi-one-dimensional (1D) waveguide networks, quantum rings (QRs), and single 1D constrictions, such as quantum point contacts (QPCs). Ther-mal non-equilibrium is realized by current heating. The charge carrier temperature is determined by noise thermometry. The electrical conductance and the voltage-noise are measured with respect to bath temperatures, heating currents, thermal gradients, and electric fields. We determine and discuss heat transport processes, electron-energy loss rates, and electronphonon interaction, and our results are consistent with the Wiedemann-Franz relation. Additionally, we show how non-thermal current fluctuations can be used to identify electric conductance anomalies due to charge states. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim