DESIGN OF A MEMS-BASED THERMO-MAGNETOELECTRICAL MEASUREMENT PLATFORM Kurt P. Pernstich, Curt A. Richter, David J. Gundlach National Institute of Standards and Technology (NIST) Gaithersburg, MD-20899
Converting heat into electricity by using thermoelectric materials (TE) for remote sensing applications or body-heat-powered devices has increased the interest in the study of TE materials.
The development of an accurate and ready-to-use measurement facility has been identified to be of crucial importance for the rapidly growing TE community [Rowe, Thermoelectrics Handbook (2006)]. Introduction of a standardized, integrated test structure and measurement protocol that is compact, readilyavailable, and easily implemented provides such a measurement solution and enables studies that yield fundamental insights to speed up the optimization anddissemination of TE materials.
We present the design of a MEMS based test structure that enables the simultaneous measurement of electrical (field-effect transistor and sheet resistivity), thermo-electrical (Seebeck), magneto-electrical (Hall), thermomagneto-electrical (Nernst), and possibly also thermal (thermal conductivity) properties of presently employed and novel TE materials from cryogenic temperatures to above room temperature.
This integrated measurement platform enables one for the first time to i) measure these fundamental microscopic properties in a single sample to remove sampleto-sample variations, ii) to study single-crystal and thin-film samples with greater precision than currently attainable, and iii) systematically change the free charge carrier concentration by using the gate electrode or optical pumping. Majoradvantages of the proposed measurement platform are the low thermal mass,which allows the modulation of the temperature, the use of lock-in techniques to improve measurement precision, and the possibility to employ the measurementplatform in any cryostat, e.g. cryostats with an optical window to simultaneouslyrecord the Raman spectra.
The presented design provides a low-cost, commercializable test structure, which will yield robust measurement data (accurate and repeatable) to enable rapidscientific and technological advancements for industrial growth.