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Abstract:
Half-Heusler compounds XYZ crystallize in the space group F (4) over bar
3m and can be viewed as a zinc-blende-like (YZ)(-) lattice partially
filled with He-like X(+) interstitials. In this work, we investigated
I-II-V (eight-electrons) half-Heusler compounds by first-principles
calculations in order to find suitable semiconductors for
optoelectronics such as Cd-free buffer layer materials for
chalcopyrite-based thin-film solar-cell devices. We report a systematic
examination of band gaps and lattice parameters, depending on the
electronegativities and the ion radii of the involved elements.
Half-Heusler buffer materials should have a band gap of more than 2 eV
to avoid absorption losses and a lattice constant of about 5.9 angstrom
to match the crystal structure of the absorber material. With these
criteria we selected seven half-Heusler compounds as candidates for a
buffer layer material.
