Four-probe measurements of the in-plane thermoelectric properties of nanofilms

Measuring in-plane thermoelectric properties of submicron thin films has remained a challenging task. Here we report a method based on a suspended microdevice for four-probe measurements of the Seebeck coefficient, thermal conductivity, electrical conductivity, and thermoelectric figure of merit of patterned indium arsenide (InAs) nanofilms assembled on the microdevice. The contact thermal resistance and intrinsic thermal resistance of the 40 nm thick InAs nanofilm sample were measured by using the nanofilm itself as a differential thermocouple to determine the temperature drops at the contacts. The microdevice was also used to measure a 190 nm thick silicon dioxide (SiO2) film and the results were compared with those reported in the literature. A through-substrate hole under the suspended microdevice allows for transmission electron microscopy characterization of the nanofilm sample assembled on the device. This capability enables one to correlate the measured thermoelectric properties with the crystal structures of the nanofilm. © 2007 American Institute of Physics.