Epitaxial growth and thermoelectric properties of TiNiSn and Zr0.5Hf0.5NiSn thin films

Due to their exceptional thermoelectric properties Half-Heusler alloys like MNiSn (M = Ti,Zr,Hf) have moved into focus. The growth of single crystalline thin film TiNiSn and Zr0.5Hf0.5NiSn by dc magnetron sputtering is reported. Seebeck and resistivity measurements were performed and their dependence on epitaxial quality is shown. Seebeck coefficient, specific resistivity and power factor for Zr0.5Hf0.5NiSn at room temperature were measured to be 63 μV K− 1, 14.1 μΩ m and 0.28 mW K− 2 m− 1, respectively. Multilayers of TiNiSn and Zr0.5Hf0.5NiSn are promising candidates to increase the thermoelectric figure-of-merit by decreasing thermal conductivity perpendicular to the interfaces. The epitaxial growth of multilayers containing TiNiSn and Zr0.5Hf0.5NiSn is demonstrated by measuring satellite peaks in the X-ray diffraction pattern originating from the additional symmetry perpendicular to the film surface.