Seebeck voltage measurement in undoped metal oxide semiconductors

Abstract

The wide-ranging inaccuracies in experimental data on the Seebeck coefficient (S) and its temperature dependence in metal oxides with no deliberate doping is attributed to the high resistivity ( ∼ 1 M Ω m ) of these materials and the poor quality of the metallic contacts formed on them. Here, we report measuring Seebeck voltages generated in such samples with a ‘zero-current’ technique that eliminates the high internal resistance-caused errors and removes the need for ohmic quality contacts. After performance demonstrations on standard samples, the method is applied for the measurement of S in undoped zinc oxide ceramic samples at different temperatures. The observed variation trends are consistent with the classic model describing thermoelectricity in semiconductors. The substantial magnitude of the room temperature S values in our ceramic samples underscores the importance of thermoelectric research on oxide ceramic materials.