Synthesis and Characteristics of Zn-Doped CuCrO2 Transparent Conductive Thin Films

The effects of doping a p-type CuCrO2 film with zinc on its structural and optoelectronic properties were investigated by experiments using CuCr1−xZnxO2 thin films (x = 0, 0.025, 0.065, 0.085). An increase in the amount of zinc dopant in the thin films affected the lattice constant and increased its Gibbs free energy of phase transformation. Cross-sectional images of the CuCrO2 thin film samples exhibited a dense polygonal microstructure and a surface morphology with protruding nanoscale granules. With the increase in the amount of Zn dopant, the surface roughness decreased, thereby increasing the amount of incident photons as well as the visible-light transmittance and ultraviolet-light absorption of the thin films. With the zinc doping in the CuCrO2 thin films, the band gap increased from 3.09 to 3.11 eV. The substitution of Cr3+ with Zn2+ forms hole carriers in the crystals, which was demonstrated by X-ray photoelectron spectroscopy and Hall effect measurements. The conductivities and carrier concentrations of the Zn-doped CuCrO2 thin films were greater than those of undoped CuCrO2. The CuCr1−xZnxO2 film (x = 0.065) exhibited the best optoelectronic properties; its carrier concentration and resistivity were 1.88 × 1017 cm−3 and 3.82 Ωcm, respectively.