Experimental observation of valence band dispersion and increased hole conductivity in CuCr1−xLixO2−ySy

Abstract Delafossite compounds are layered ternary oxides known for simultaneous exhibition of significant carrier conduction and optical transparency. To survey effect of simultaneous cationic and anionic hole doping in prototype delafossite CuCrO2, we have analyzed the structural, optical, impedance and transport mechanism of CuCr 1 − x Li x O 2 − y S y (x and y ranging 0–2 atomic %) prepared by solid state heating. The substitutional site occupancy of Li Cr • • and S O × are confirmed and quantified by Rietveld analysis. Valence band dispersion is demonstrated upon Li Cr • • and S O × co-doping by x-ray photoelectron spectroscopy with extended contribution from shallow S 3p antibonding states. From diffuse reflectance spectra, the optical gap (~3.5 eV) is evaluated to be wide even upon co-doping. Carrier density and hole mobility for CCO / ( Li Cr • • + S O × ) to be 5.32 × 1015 cm−3 and 23.50 cm2V−1s−1, respectively. This scheme of band engineering is indicative of a more persuasive alternative to reach the hole conductivity bottleneck threshold.