In-plane thermoelectric properties characterization of a Si/Ge Superlattice using a microfabricated test structure

摘要

In this work we present an experimental technique for the characterization of thermoelectric properties of thin films in the in-plane direction. The technique employs a micro-fabricated array of heaters/sensors deposited onto the film in order to monitor the temperature, the Seebeck voltage and the electrical voltage of the thermoelectric film. The thermal diffusivity and thermal conductivity of the film are determined from the decay of the temperature profile detected over a wide frequency range by arrays of temperature sensors around a microscale heater. The temperature profile and the Seebeck voltage monitored by the voltage electrodes are used to determine the Seebeck coefficient of the thermoelectric films in the in-plane direction. The substrate influence on the thermoelectric properties measurements is eliminated by the removal of the substrate over a wide area underneath the heater and the monitoring electrodes. Electrical conductivity measurements are carried out without heating based on the 4-probe method. Test structures are fabricated and thermoelectric properties characterization is carried out for a Si/Ge superlattice.