Thermoelectric transport properties of porous silicon nanostructure

We evaluated the in-plane thermoelectric transport properties of self-supporting porous silicon samples which were prepared through anodization of degenerate silicon wafer. Rapid decrease of both electrical and thermal conductivity were observed alter the anodization. The thermal conductivities decreased by two orders, while the electrical conductivities were three to five orders of magnitude lower than that of initial silicon at room temperature. Increase of Seebeck coefficient was observed for the 69% porous PS sample and the figure of merit was larger than that of initial silicon. It was found that the reduction in electrical conductivity is larger than that of thermal conductivity. Low conductivity of PS indicates localized carriers due to depletion of carrier and strong scattering taking place in residual silicon nanostructure.