An automated microprobe for temperature dependent spatial scanning of the Seebeck coefficient

The common principle of scanning the Seebeck coefficient at the surface of a thermoelectric material is based on simultaneous measurement of two thermo-voltages, caused by a temperature gradient between a tip-shaped hot microprobe and the sample. A pointed probe mounted to a three dimensional micro-positioning system allows the determination of the individual thermopower of each single sample position. So far, this method has only been working at ambient temperature. Recent improvement of the measuring device by the implementation of a cooling/heating system led to an expansion of the sample temperature ranging between about 30 K below and above room temperature and enables computer controlled repeated scans on the sample surface at different stabilised temperatures set in user defined steps. In this way, along with the sample homogeneity, the temperature dependence of the Seebeck coefficient near room temperature can be determined at different locations of the sample, facilitating an advanced analysis of thermoelectric materials.