Thermoelectric figure of merit of II-VI semiconductor nanowires

The room temperature thermoelectric figure of merit and power factor are calculated for bulk and nanowires made of CdTe, ZnTe, ZnSe, and ZnS, of the zincblende structure. To this end, an iterative solution of the Boltzmann transport equation is used to obtain the electronic transport properties. The lattice thermal conductivity is estimated using a full dispersion transmission function approach. A saturation to finite values is predicted for the power factor in the small thickness limit. The figure of merit increase upon thickness reduction is largest for CdTe, followed by ZnTe, ZnSe, and ZnS. II-VI nanowires show smaller increases of the figure of merit as compared with III-V nanowires, despite their bulk values are of comparable magnitude in the two groups. The reasons for this are explained. (C) 2004 American Institute of Physics.