Structural and electrical properties of CuIn _1-x Al _x Se ₂ thin films prepared by radio-frequency magnetron sputtering process

The CuIn _1-x Al _x Se ₂ (CIAS) thin films have been prepared by radio-frequency magnetron sputtering process. X-ray diffraction patterns indicate that the lattice constants of the CIAS thin films show about a 2% reduction with the Al content from 0 to 12%. The results of Raman scatting spectroscopy show that the A ₁ mode position exhibits a blueshift with the increasing Al content. The grain size becomes smaller evidently with the increase of Al content. From the current-voltage characteristics of the interface for Al-ZnO/CIAS thin films, the threshold voltage decreases varying from darkness to illumination, the barrier heights are 0.775 eV in the dark and 0.697 eV under light illumination, respectively, and the values of ideality factor vary from 2.19 to 1.96 in the dark and under light illumination from the d(V)/d(ln I) versus I curve. The AZO/CIAS thin film exhibits good spectral response in wavelengths ranging from 450 nm to 750 nm. The results indicate that the CIAS thin film is a potential material for photodetector application.