Thermoelectric thin-film high-temperature measurements by computer control

Abstract

This paper describes the design and performance of a novel automated apparatus for measuring the Seebeck coefficient (S) and the electrical conductivity (σ) of thin-film thermoelectric materials continuously over the temperature range of 20 to 1000 °C. An inert substrate coated with a thin film thermoelectric material is increased and decreased in temperature at a predetermined rate set by program control while maintaining a constant temperature gradient across the sample. A fully automated computer data acquisition system is used to control instrumentation, measurements, and data storage. This approach is particularly useful for studying the transition from amorphous to crystalline structure in the semiconducting materials. Thin-film thermoelectric materials were prepared by magnetron sputtering and rf glow discharge. Parameters S and σ were measured as a function of temperature, histology, type, and amount of doping. Materials studied had the compositions Bi2Te3, GeTe, Ge80Te20, PbTe, and S.