Enhanced thermoelectric performance of InSb through deep level impurity donor state induced by La doping

As one member of III-V semiconductors that have a variety of applications, InSb also shows great potential in thermoelectrics owing to its high mobility. In this work, the thermoelectric performance of n-type polycrystalline InSb is improved by La doping, which induces deep level impurity donor state and massive defects, synergistically optimizing both electrical and thermal transport properties. The peak power factor of La-doped InSb is enhanced from 42 to 58 μW cm−1 K−2 at 773 K due to the enlarged carrier concentration provided by the deep level donor state. Meanwhile, lattice thermal conductivity decreases from 3.2 to 1.7 W m−1 K−1 at 773 K due to In precipitates, point defects and local atomic disorder. Consequently, the peak zT of La-doped InSb is promoted to 0.85 at 773 K, which is among the best value in III-V compounds.