Influence of Post-Annealing Conditions on the Formation of Delafossite-CuCrO 2 Films

Abstract

The influence of post-annealing conditions, the partial oxygen pressures (pO2) and temperatures, on the formation of CuCrO2 films is examined in this study. The sol-gel derived films were annealed at 500°C in air and post-annealed at 600°C to 850°C in pO2 = 10 -3 atm to pO2 = 0.21 atm. The CuO and CuCr 2O4 phases appeared above pO2 = 10-2 atm and 600°C of post-annealing, whereas a pure delafossite-CuCrO 2 phase was detected when the films were post-annealed in pO 2 = 10-3 atm above 600°C. The binding energies of Cu-2p3/2 at 932.2 and 934.3 eV, and satellites were observed because the post-annealed films had CuO and CuCr2O 4 phases. The binding energy of Cu-2p3/2 was 932.2 eV because the post-annealed films had a delafossite-CuCrO2 phase. A binding energy of Cr-2p3/2 at 576.2 eV was observed when the post-annealed films had CuCr2O4 or delafossite-CuCrO 2 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) × 10-2 Scm-1 with the carrier concentrations of (1.3-1.9) × 1017 cm-3. © 2012 The Electrochemical Society. All rights reserved.