Characterization of CuInS2 thin films prepared by aerosol jet deposition

CuInS2 thin films were prepared using an aerosol jet deposition (AJD) technique with an aqueous solution of CuCl2, InCl3 and thiourea on a heated glass substrate. X-ray diffraction patterns showed that well-crystallized thin films with a preferential (112) orientation could be deposited at 400 °C and [Cu]/[In] molar ratio of 1.2. Field emission scanning electron microscopy revealed well-crystallized grains in the films produced at high temperature of 400 °C. In addition, energy dispersive X-ray spectroscopy confirmed that excess Cu and S were required to achieve well-crystallized CuInS2 films. As the [Cu]/[In] molar ratio increased from 0.8 to 1.4, the highest intensity of the (112) orientation and better crystallization were obtained at a [Cu]/[In] ratio of 1.2. The [Cu]/[In] ratios in the film were always higher than those in the precursor solution. All the CuInS2 thin films turned out to be p-type and had a band gap of 1.4 eV. The depth profiles of Cu, In and S in the CuInS2 thin films deposited at the optimal [Cu]/[In] and [S]/[In] ratios of 1.2 and 3, respectively, were relatively constant throughout the films. Overall, the CuInS2 thin films deposited using the AJD method have well grown grains with good crystallinity.