Characteristics of p-type transparent conductive CuCrO2 thin films

Cu-Cr-O films were prepared using reactive magnetron sputtering deposition followed by annealing at temperatures ranging from 550 to 625 °C in 25 °C increments. Correlations between the optoelectronic and microstructural properties of the p-type CuCrO2 films are discussed. The as-deposited film was amorphous; after annealing at 550 and 575 °C, films adopted mixed CuO and CuCr2O4 phases. Annealing at 600 °C led to the formation of a dominant phase of delafossite CuCrO2. The 625 °C-annealed film was single-phase CuCrO2 which had a bar- and polygonal-like mixed surface appearance, with a root mean square roughness of 17.7 nm. CuCrO2 is an intrinsic p-type semiconductor which exhibits electrical conductivity and transparency over the visible wavelength range. Two higher-energy subband transitions at 3.69 and 4.82 eV were observed in the band structure of CuCrO2. Point defects were the main reason source of hole carrier scattering in the material. The single-phase CuCrO2 film had the lowest resistivity of the films, 4.31 Ω cm, and had a direct band gap of 3.14 eV and light transmittance of 62% at 600 nm.