Cu 2 ZnSnS 4 (CZTS) is a p-type semiconductor that has been seen as a possible low-cost replacement for Cu(In,Ga)Se 2 in thin film solar cells. So far compound has presented difficulties in its growth, mainly, because of the formation of unwanted phases like ZnS, Cu x SnS x+1 , Sn x S y , Cu 2−x S and MoS 2 . X-ray diffraction analysis (XRD), which is mostly used for phase identification cannot resolve some of these phases from the kesterite/stannite CZTS and thus the use of a complementary technique is needed. Raman scattering analysis can help distinguishing these phases not only laterally but also in depth. Knowing the absorption coefficient and using different excitation wavelengths in Raman scattering analysis, one is capable of profiling the different phases present in multi-phase CZTS thin films.This work describes in a concise form the methods used to grow chalcogenide compounds, such as, CZTS, Cu x SnS x+1 , Sn x S y and cubic ZnS based on the sulphurization of stacked metallic precursors. The results of the films' characterization by XRD, electron backscattered diffraction and scanning electron microscopy/energy dispersive spectroscopy techniques are presented for the CZTS phase. The limitation of XRD to identify some of the possible phases that can remain after the sulphurization process are investigated. The results of the Raman analysis of the phases formed in this growth method and the advantage of using this technique in identifying them are presented. Using different excitation wavelengths it is also analysed the CZTS film in depth showing that this technique can be used as non destructive methods to detect unwanted phases.

Abstract:In the present work we report the results of the growth, morphological and structural characterization of Cu 2 ZnSnS 4 (CZTS) thin films prepared by sulfurization of DC magnetron sputtered Cu/Zn/Sn precursor layers. The adjustment of the thicknesses and the properties of the precursors were used to control the final composition of the films. Its properties were studied by SEM/EDS, XRD and Raman scattering. The influence of the sulfurization temperature on the morphology, composition and structure of the films has been studied. With the presented method we have been able to prepare CZTS thin films with a kesterite structure.