Preparation of p-type conductive transparent CuCrO_2:Mg thin films by chemical solution deposition with two-step annealing

摘要

Mg-doped copper-chromium oxide (CuCrO_2:Mg) thin films are prepared on glass substrate by chemical solution deposition. Metal acetate salts are examined as metal sources in the precursor solution for the preparation of CuCrO_2:Mg thin films. Annealing conditions, such as ambient gas and temperature, are investigated in order to produce pure CuCrO_2 phase p-type conductive thin films at a relatively lower process temperature. Single-phase delafossite CuCrO_2 structures are obtained by subsequent two-step annealing at 400 °C in 5% forming gas ambient, followed by a rise to sintering temperature in a nitrogen atmosphere. Annealing in forming gas reduces Cu(II) ion to Cu(I) and inhibits the formation of spinel-type CuCr_2O_4, thus allowing CuCrO_2 to form at 500 °C. The transmittance of the CuCrO_2 thin films is above 50% in the visible region and increases with increases in the sintering temperature. The highest conductivity is obtained with sintering at 600 °C, and a resistivity of 0.31 Ω cm is achieved.