Enhancement of thermoelectric figure of merit of nanostructured FeSb$_{2}$ by adding Cu nanoparticles

We present the enhancement of thermoelectric properties of FeSb$_{2}$ through modulation doping by Cu nanoparticles. Since, FeSb$_{2}$ and Cu have matched work function, the electrical conductivity of this Kondo-like system can be increased dramatically without affecting Seebeck coefficient. The optimized nanocomposite FeSb$_{2}$Cu$_{0.045}$ has enhancement of power factor by 90{\%} compared to pure nanostructured FeSb$_{2}$. The further reduction of thermal conductivity from FeSb$_{2}$/Cu interface gives the total enhancement of figure of merit (ZT) by 110{\%}. This strategy has been widely used on other semiconductors to improve ZT. Our result demonstrates that the potential of the modulation doping technique can also be extended to Kondo insulator systems.