Apparatus for Seebeck Coefficient Measurements on High-Resistance Bulk and Thin-film Samples

The main challenge in thermoelectric metrology is an accurate Seebeck coefficient measurement on high electrical resistance bulk and thin-film samples, as the loading by the measuring device causes a considerable voltage drop on the internal resistance of the sample. It has been shown that this technical problem can be solved by utilizing the zero current technique of measurement. Here, an apparatus for the simultaneous measurement of the Seebeck coefficient and electrical resistance of bulk and thin-film samples using zero current measurement technique is presented, which automatically measures these quantities at different temperature profiles at steady-state, quasi-steady-state, and transient conditions in different atmospheres. Thick-film tin oxide microheaters are utilized to provide the desired temperature gradient along with the sample from room temperature up to 1200 K, and zero current method is used to eliminate errors originating from the high internal resistance of the sample. As examples, Seebeck voltages and electrical resistances are measured on the bulk and thin-film zinc oxide samples with internal resistances in the megohm (M Omega) range. Operating the device for measurements involving time-varying temperature gradients is demonstrated.