Reactive sputtering preparation of CuInS2 thin films and their optical and electrical characteristics

In this paper a preparation method for CuInS2 films by reactive sputtering together with vacuum rapid annealing was presented, and the surface morphology, microstructure, composition and photo-electrical characteristics of the CuInS2 films were investigated. X-ray diffraction (XRD) analyses revealed that the annealed samples are CuInS2 with the single chalcopyrite phase and a preferential crystalline orientation along (112). The free-void and compact film with the grain size of about 200 nm, as shown by scanning electron microscopy and stylus profiler (α-step) measurements, has been obtained by optimizing the processing parameters. The samples were also characterized by energy dispersive X-ray analysis, showing the constituent ratio [Cu + In]/[S] and [Cu]/[Cu + In] of about 1 and 0.5, respectively. All CuInS2 films have a good homogeneity in shape and size of the grains and in distribution of constituent and defects as revealed by fourier transform infrared spectrometer analysis. The experiment indicated that the reactive sputtering together with vacuum rapid annealing treatment is beneficial to promote genuine realization of the large-scale production of the ultra-high efficiency Cu-III-VI2 thin film solar cells.