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Effect of surface treatment by hydrogen peroxide solution on Cu
 2
 ZnSnS
 4
 thin films

Cu2ZnSnS4 (CZTS) is one of the promising materials of absorber layer used in thin film solar cells. In this paper, we revealed the effects of surface treatment by hydrogen peroxide solution on the chemical and structural properties of CZTS thin films in order to improve the conversion efficiency. On the Raman spectra, the full width at half maximum (FWHM) of A1 peak at around 338 cm−1 is not affected by H2O2 solution treatment. However, Raman scattering spectroscopy results showed that the existence of not only CZTS but also oxide was confirmed by the H2O2 solution treatment. From the XPS spectra, Zn, and S were dissolved by H2O2 solution. The surface oxidation takes place in a very short period of time. The sulfate phase is existence on the CZTS surface by H2O2 surface treatment.