CuInS₂Thin Films Obtained By Solid-State Sulfurization

Copper indium disulfide (CuInS2) is one of the most promising absorber materials for thin film solar cells because of its direct band gap (1.50eV) at room temperature being close to the ideal band gap (1.45eV), and high optical absorption coefficient (105cm-1) for considerable conversion efficiency. CuInS2thin films were prepared by sulfurization of Cu-In precursors which were prepared by magnetron sputtering method. This paper investigated the influencing factors of preparing the CuInS2thin film by solid-state sulfurization and its photoelectric properties. The obtained films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), UV-vis spectrophotometer and Hall effect measurement. The CuInS2thin films obtained at different sulfurization temperatures and sulfurization times were investigated. The CuInS2thin film was successfully prepared for solar cells.The results show that15W was the best sputtering power for forming Cu-In precursor films. The CuInS2thin films sulfurized at450℃for20min were chalcopyrite structure,(112) preferred orientation and1.48eV of the band gap. The study also show that almost no change in the composition of the films, the crystallization of the film was better and the band gap of the film was lager by increasing the sulfurization temperature. The influence on the film composition was tiny, the crystallization of the film was becoming better and better, the resistivity of the film was increasing, the band gap of the film was bigger and bigger with the increase of the sulfurization time.