A modified high-resolution TEM for thermoelectric properties measurements of nanowires and nanotubes

Nanowires are interesting candidates for thermoelectric applications because of their potentially low thermal conductivity and high power factor. However, measurements at the single-wire level are challenging and tend to lack detailed information about the atomic-level structure of the sample and contacts. We are modifying a high-resolution transmission electron microscope (HRTEM) with integrated scanning tunneling microscope (STM) for in-situ measurements of the thermoelectric properties of individual nanowires and nanotubes. A slender hot-wire probe is used to make electrical and thermal contact to the free end of a nanowire or nanotube. The electrical conductance of the nanowire/nanotube can be measured with the usual STM mode of operation. The Seebeck coefficient can be extracted from the transient response to a step change in the joule heating of the hot-wire probe. The thermal conductance can be calculated from the temperature and heat leakage of the hot-wire probe. These measurements are combined with detailed HRTEM observations.