Effect of the annealing process on CuInS2 thin films prepared by using aerosol jet deposition

CuInS2 thin films were prepared on soda lime glasses by using the aerosol jet deposition (AJD) method. The effects of the [Cu]/[In] ratio and the annealing process on the properties of the CuInS2 thin films were studied. The X-ray diffraction (XRD) analysis showed that well-crystallized films were deposited at a [Cu]/[In] ratio of 1.2 and a [S]/[In] ratio of 3. In order to improve the quality of the films, we explored various post-deposition annealing processes including furnace annealing in Ar, one-step sulfurization and two-step sulfurization. XRD and field emission scanning electron microscopy revealed that highly-crystallized grains were obtained in the films when two-step sulfurization was used. Energy dispersive X-ray analysis confirmed that two-step sulfurization in a H2S ambient eliminated the deficiency of sulfur and removed impurities such as oxygen and chlorine. The depth profiles of Cu, In and S for the CuInS2 films confirmed the effectiveness of two-step sulfurization for fabricating high quality CuInS2 films. Finally, deposition of high-quality CuInS2 films by using the AJD method could be achieved by the introduction of two-step sulfurization.