Structural, optical and electrical characterization of ZnO:Ga thin films for organic photovoltaic applications

摘要

Gallium-doped zinc oxide (ZnO:Ga) films were prepared on glass substrates by RF magnetron sputtering. The effect of growth temperature on microstructure, optical and electrical properties of the films was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectrophotometer and four-point probe. The results show that all the films are polycrystalline and (002) oriented, and that the growth temperature significantly affects the microstructure and optoelectrical properties of the films. The film deposited at 670K has the largest grain size of 71.9nm, the lowest resistivity of 8.3×10~(-4)Ω·cm and the highest figure of merit of 2.1 × 10~(-2) Ω~(-1). Furthermore, the optical energy gaps and optical constants were determined by optical characterization methods. The dispersion behavior of the refractive index was also studied using the Sellmeir's dispersion model and the oscillator parameters of the films were obtained.