Characteristics of p-type transparent conductive CuCrO_2 thin films

摘要

Cu-Cr-O films were prepared using reactive magnetron sputtering deposition followed by annealing at temperatures ranging from 550 to 625 ℃ in 25 ℃ increments. Correlations between the optoelectronic and microstructural properties of the p-type CuCrO_2 films are discussed. The as-deposited film was amorphous; after annealing at 550 and 575 ℃, films adopted mixed CuO and CuCr_2O_4 phases. Annealing at 600℃ led to the formation of a dominant phase of delafossite CuCrO_2. The 625 C-annealed film was single-phase CuCrO_2 which had a bar- and polygonal-like mixed surface appearance, with a root mean square roughness of 17.7 nm. CuCrO_2 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 CuCrO_2. Point defects were the main reason source of hole carrier scattering in the material. The single-phase CuCrO_2 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.