Porous silicon (Si) nanostructures with heavily doping concentrations possess many intriguing properties different from bulk Si, but the fabrication remains greatly challenging for the large-quantity production. Therefore, in this study, the heavily doped Si nanowires with highly porous features were prepared using a co-solvent mediated metal-assisted chemical etching (MaCE). Unlike the conventional MaCE method with sole water as solvents, the mixed co-solvents, with the addition of highly volatile methanol at ambient temperature are found to facilitate the significant sidewall etching through the evaporation of solvents when etching reaction proceeds. In addition, thermoelectric performances of incorporating such porous Si nanowires as inclusions with (BiSb)2Te3 particles as matrix were investigated. The beneficial effects, examined from three various amounts of Si nanowires dispersed in (BiSb)2Te3 matrix, are originated from the supplement of increased carrier concentrations. Meanwhile, the increase of thermal conductivity is not obvious due to the existence of porous Si nanowires, thus leading to the improved figure of merit (ZT) value, which is more than 1.3 times higher than that of pure (BiSb)2Te3 samples.
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