Summer 2011 Intern Project- Thomas Neulinger

EPITAXIAL GROWTH AND CHARACTERIZATION OF  THIN-FILM HALF-HEUSLER NiTiSn


Thomas Neulinger

Physics
UC Santa Barbara

Mentor: Jason Kawaski
Faculty Advisor: Chris Pamlstrom
Department: Materials and Electrical and Computer Engineering

The half-Heusler phase of NiTiSn has a number of interesting properties: it is semiconducting--though its constituents are metals, and it promises to be a good thermoelectric because of its narrow band gap and high Seebeck coefficient. Currently, NiTiSn has been studied only in bulk form, and its fundamental properties are not fully understood. Further studies require higher-quality single crystals, for which growth by molecular beam epitaxy (MBE) is well-suited. We demonstrate the growth of NiTiSn on MgO (001) substrate. Reflection high energy electron diffraction (RHEED), low energy electron diffraction (LEED), and X-ray diffraction (XRD) confirm that the films are single-crystal and epitaxial, with a 45 degree rotated cube-on-cube relationship. Preliminary electrical transport measurements suggest that the films are semiconducting at low temperatures.

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