Abstract:
BaCuQF (Q=S,Se) materials, candidate transparent p-type conductors, were prepared by
solid-state reaction, and their bulk electrical and optical properties were evaluated. The
room-temperature Seebeck coefficient and electrical conductivity of undoped BaCuQF pellets were
+56 μV/K and 0.088 S/cm, respectively, for the sulfide fluoride, and +32 μV/K and 0.061 S/cm,
respectively, for the selenide fluoride. The conductivity was greatly enhanced by the substitution of
several percent of K for Ba; the highest conductivities were 82 S/cm for Ba₀.₉K₀.₁CuSF and 43 S/cm
for Ba₀.₉K₀.₁SeF. The band gaps for Q=S and Q=Se were measured to be 3.2 and 3.0 eV,
respectively. Undoped BaCuSF exhibits strong red luminescence near 630 nm under ultraviolet
excitation.
