Thermoelectric semiconductor and electrode fabrication and evaluation of SiGe/electrode

Joints between a Silicon-Germanium thermoelectric semiconductor and electrodes were prepared by hot-pressing. Tungsten or carbon electrodes were joined to either side of n-type Si0.8Ge0.2 (P 0.3 atomic %) respectively, with thin sheets of titanium foil inserted between them, and then pressed and joined at 1523K in vacuum. The size of the resulting electrode/SiGe semiconductor/electrode units measured 5mm x 5mm x 9mm. Observations through SEM and EPMA showed the presence of many voids in the junction layers of the SiGe/tungsten electrodes, whereas the SiGe/carbon electrodes exhibited no voids in their junction layers. In the SiGe/carbon electrodes, the titanium atoms were enriched in the junction layer, and other atoms also remained undiffused. In the SiGe/tungsten electrodes, the tungsten and silicon atoms showed counter diffusion.