Electronic structure and thermoelectric properties of epitaxial S c 1 − x V x N y thin films grown on MgO(001)

The electronic structure of S{c}_1−x{V}_x{N}_y epitaxial films with different alloying concentrations of V are investigated with respect to effects on thermoelectric properties. Band structure calculations on S{c}_0.75{V}_0.25N indicate that V 3d states lie in the band gap of the parent ScN compound in the vicinity of the Fermi level. Thus, theoretically, the presence of light (dispersive) bands at the Γ point with band multiplicity is expected to lead to lower electrical resistivity, while flat (heavy) bands at X−W−K symmetry points are associated with higher Seebeck coefficients than that of ScN. Hence, to probe the thermoelectric properties experimentally, epitaxial S{c}_1−x{V}_x{N}_y thin film samples were deposited on MgO(001) substrates. All the samples showed N substoichiometry and pseudocubic crystal structure. The N-vacancy-induced states were visible in the Sc 2p x-ray absorption spectroscopy spectra. The reference ScN and S{c}_1−x{V}_x{N}_y samples up to x=0.12 were n type, exhibiting carrier concentration of {10}²¹c{m}⁻³ , typical for degenerate semiconductors. For the highest V alloying of x=0.15 , holes became the majority charge carriers, as indicated by the positive Seebeck coefficient. The underlying electronic structure and bonding mechanisms in S{c}_1−x{V}_x{N}_y influence the electrical resistivity, Seebeck coefficient, and Hall effect. Thus, this paper contributes to the fundamental understanding to correlate defects and thermoelectric properties to the electronic structure in the Sc-N system with V alloying. Published by the American Physical Society 2024