Transparent conductive CuFeO2 thin films prepared by sol–gel processing

In this study, transparent conductive CuFeO2 thin films were deposited onto a quartz substrate using a low-cost sol–gel process and sequential annealing in N2. The sol–gel derived films were annealed at 500 °C for 1 h in air and then annealed at 700 °C in N2 for 2 h. The CuO and CuFe2O4 phases appeared as the film annealed in air, and a single CuFeO2 phase (delafossite, R3m) appeared as the film annealed in N2. X-ray photoelectron spectroscopy showed that the chemical composition of the CuFeO2 thin films was similar to the stoichiometry. The optical bandgap of the CuFeO2 thin films was 3.1 eV. The p-type characteristics of the films were verified by Hall-effect measurements. The electrical conductivity and carrier concentration of the CuFeO2 thin films were 0.358 S cm−1 and 5.34 × 1018 cm−3, respectively. These results show that the proposed low-cost sol–gel process provides a feasible method of depositing transparent CuFeO2 thin films.