Electronic structure and thermoelectric properties of epitaxial Sc1−xVxNy thin films grown on MgO(001)

• Published in: Physical review. B 2024-09, Vol.110 (11)
• Main Authors: Chowdhury, Susmita, Singh, Niraj Kumar, Honnali, Sanath Kumar, Greczynski, Grzegorz, Eklund, Per, le Febvrier, Arnaud, Magnuson, Martin
• Format: Article
• Language: English
• ISSN: 2469-9950; 2469-9969
• DOI: 10.1103/physrevb.110.115139

The electronic structure of S⁢c1−x⁢Vx⁢Ny epitaxial films with different alloying concentrations of V are investigated with respect to effects on thermoelectric properties. Band structure calculations on S⁢c0.75⁢V0.25⁢N indicate that V 3⁢d 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⁢c1−x⁢Vx⁢Ny 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 2⁢p x-ray absorption spectroscopy spectra. The reference ScN and S⁢c1−x⁢Vx⁢Ny samples up to x=0.12 were n type, exhibiting carrier concentration of 1021 c⁢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⁢c1−x⁢Vx⁢Ny 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.