Thermal biasing at the nanoscale

We present an innovative strategy to control a thermal bias in nanoscale electronic conductors which is based on the contact heating scheme. This straightforward approach allows one to apply a known thermal bias across nanostructures directly through metallic leads, avoiding conventional substrate intermediation. We show, by using the average noise thermometry and local noise sensing technique in InAs nanowire based devices, that a nanoscale metallic constriction on a SiO2 substrate acts like a diffusive conductor with negligible electron-phonon relaxation and non-ideal leads. The non-universal impact of the leads on the achieved thermal bias, which depends on their dimensions, shape and material composition, can be quantified via a proper design of the nanodevice. Our results are relevant for accurate thermoelectric or similar measurements at nanoscale, allowing to reduce the issue of the thermal bias calibration to the knowledge of the heater resistance.