Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 24: Thermoelectricity
HL 24.3: Vortrag
Dienstag, 17. März 2015, 10:00–10:15, EW 202
First principles calculations of point defects to optimize the thermoelectric efficiency of half-Heusler compounds. — •Robin Stern and Georg Madsen — Ruhr-Universität Bochum, ICAMS
In future, thermoelectric materials can play a significant role in enhanced energy efficiency. The thermoelectric performance of a material is determined by the power-factor, S2σ and the thermal conductivity κ. Half-Heusler compounds, consisting of three interpenetrating fcc sublattices, are an interesting class of materials, since they exhibit a relatively large Seebeck coefficient S. Furthermore, each sublattice can be doped independently to increase the power-factor and lower the thermal conductivity. The power-factor is strongly influenced by the carrier concentration. We used DFT point-defect calculations to evaluate the defect formation energies of various dopants and studied the influence on the carrier concentration. Using the example of NiTiSn, we discuss how the growth conditions of the half-Heusler compound influences the intrinsic carrier concentration and how extrinsic doping can significantly increase the latter.