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The effects of Ge partial substitution for Si on the thermoelectric properties of CoSi1−xGex alloys were investigated by means of thermal and electrical transport measurements. Electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) measurements were performed on a series of CoSi1−xGex alloys with x varying from 0 to 0.15. A substantial decrease in electrical resistivity and lattice thermal conductivity was noticed with increasing substitution level, whereas the Seebeck coefficient shows a weak variation with respect to Ge concentration. The thermoelectric efficiency was found to be enhanced by an order of magnitude in CoSi with Ge substitution. These observations were interpreted on the basis of the changes in the electronic band structure induced by Ge substitution.

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An innovative concept of twin-enhanced thermoelectricity was proposed to fundamentally resolve the high electrical resistance while not degrading the phonon scattering of the thermoelectric nanoassemblies. Under this frame, a variety of highly oriented and twinned bismuth antimony telluride (BixSb2-xTe3) nanocrystals were successfully fabricated by a large-area pulsed-laser deposition (PLD) technique on insulated silicon substrates at various deposition temperatures. The significant presence of the nonbasal- and basal-plane twins across the hexagonal BiSbTe nanocrystals, which were experimentally and systematically observed for the first time, evidently contributes to the unusually high electrical conductivity of ~2700 S cm(-1) and the power factor of ~25 μW cm(-1) K(-2) as well as the relatively low thermal conductivity of ~1.1 W m(-1) K(-1) found in these nanostructured films.