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R. Stern, B. Dongre, G. Madsen:
"Extrinsic doping of the half-Heusler compounds";
Nanotechnology, 27 (2016), 1 - 6.

Controlling the p- and n-type doping is a key tool to improve the power-factor of thermoelectric
materials. In the present work we provide a detailed understanding of the defect thermochemistry
in half-Heusler compounds. We calculate the formation energies of intrinsic and extrinsic defects
in state of the art n-type TiNiSn and p-type TiCoSb thermoelectric materials. It is shown how the
incorporation of online repositories can reduce the workload in these calculations. In TiNiSn we
find that Ni- and Ti-interstitial defects play a crucial role in the carrier concentration of TiNiSn.
Furthermore, we find that extrinsic doping with Sb can substantially enhance the carrier
concentration, in agreement with experiment. In case of TiCoSb, we find ScTi, FeCo and SnSb
being possible p-type dopants. While experimental work has mainly focussed on Sn-doping of
the Sb site, the present result underlines the possibility to p-dope TiCoSb on all lattice sites.

half-Heusler compounds, defect thermochemistry, DFT repository

http://dx.doi.org/10.1088/0957-4484/27/33/334002