Influence of Post-Annealing Conditions on the Formation of Delafossite-CuCrO2 Films

The influence of post-annealing conditions, the partial oxygen pressures (pO(2)) and temperatures, on the formation of CuCrO2 films is examined in this study. The sol-gel derived films were annealed at 500 degrees C in air and post-annealed at 600 degrees C to 850 degrees C in pO(2) = 10(-3) atm to pO(2) = 0.21 atm. The CuO and CuCr2O4 phases appeared above pO(2) = 10(-2) atm and 600 degrees C of post-annealing, whereas a pure delafossite-CuCrO2 phase was detected when the films were post-annealed in pO(2) = 10(-3) atm above 600 degrees C. The binding energies of Cu-2p(3/2) at 932.2 and 934.3 eV, and satellites were observed because the post-annealed films had CuO and CuCr2O4 phases. The binding energy of Cu-2p(3/2) was 932.2 eV because the post-annealed films had a delafossite-CuCrO2 phase. A binding energy of Cr-2p(3/2) at 576.2 eV was observed when the post-annealed films had CuCr2O4 or delafossite-CuCrO2 phases. The formation of a delafossite-CuCrO2 phase in the post-annealing processing is in good agreement with thermodynamics. The transmittance of delafossite-CuCrO2 films was 60-75% in the visible region and the direct optical bandgap of delafossite-CuCrO2 films was 3.0-3.05 eV. The positive Seebeck coefficients revealed the p-type characteristics in the delafossite-CuCrO2 films. The electrical conductivity of the delafossite-CuCrO2 films was (2.0-3.8) x 10(-2) Scm(-1) with the carrier concentrations of (1.3-1.9) x 10(17) cm(-3). (C) 2013 The Electrochemical Society.