A simple structure of planar silicon nanowire (SiNW)-based thermoelectric (TE) generators (TEGs) is presented in this paper, which has the ability to sustain temperature difference along SiNW under ultrashort channel length for achieving mW/cm2-class power output from environmental heat energy. The TE performance of the proposed SiNW-based TEGs was evaluated by finite-element simulation and analytic modeling. The channel length, pad length, and the thickness of the SiO2 layer were varied in the model while keeping a series of constant proportions toward finding the optimal SiNW-based TEG structure for high power generation. Based on the analysis, we demonstrated that decreasing the dimension of SiNW-based TEG is beneficial to improving the total TE power density. A very high power density of 4.2 mW/cm2 is possible to be achieved at SiNW length of μm and pad length of μm under a temperature difference of 5 K across the hot and cold regions. The miniaturized SiNW-based TEG has a great potential to obtain the output power density which is 100-1000 times higher than conventional planar TEGs with air cavity but has a simple structure and can easily be fabricated.
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