Ultrahigh-temperature vacuum prober for electrical and thermal measurements

We develop an ultrahigh-temperature vacuum probe station (UHT-VPS) featuring a sample holder heated by thermal radiation from a silicon carbide heater. This contactless configuration electrically isolates the sample from the high-power heating source through a vacuum gap, ensuring reliable measurements under extreme conditions. The capability of this UHT-VPS to measure electrical signals from 30 nV upward on bulk sapphire is demonstrated through the 3ω/2ω method. The measurements are continuously operated from 300 to 1150 K, under a high vacuum of 2 × 10-6 mbar, for a total of about 66 h without readjusting the contact, and yield the linear and quadratic temperature coefficients of resistance of chromium/platinum micro-resistances, as well as the sapphire's thermal conductivity and thermal diffusivity. By recording the heater and sensor temperature signals up to 30 kHz and fitting them with theoretical models that take into account the quadratic temperature coefficient of resistance of Cr/Pt microwires, we obtain values in agreement with the literature data determined by optical methods. In this range of temperature, we also measure thermal conductivity, which cannot be directly accessed by optical methods. Our system thus provides an effective solution for simultaneously retrieving the electrical and thermal properties of materials using a single set of 3ω/2ω data up to unprecedented temperature levels.