Research on the properties of ZnO_(1-x)S_(x) thin films modified by sulfur doping for CIGS solar cells

ZnO_(1-x)S_(x) thin films modified by sulfur doping were prepared on glass substrates by chemical bath deposition(CBD) for studying the effect of thiourea concentration on the thin film properties. The obtained ZnO_(1-x)S_(x) thin films were characterized by scanning electron microscopy(SEM), which shows the surfaces of ZnO_(1-x)S_(x) thin films deposited under the thiourea concentration of 0.14 M are more compact. X-ray diffraction(XRD) measurement shows that the ZnO_(1-x)S_(x) thin films with hexagonal crystal structure had strong diffraction peaks and better crystallinity. The optical transmittance of the ZnO_(1-x)S_(x) thin films with 0.14 M thiourea concentration is above 80% in the wavelength range of 300-900 nm. According to the measurement results from spectrophotometer, the ZnO_(1-x)S_(x) band gap energy value Eg varies nonlinearly with different S/(S+O) ratio x, and increases with the increase of x. There is a band gap value of 2.97 eV in the ZnO_(1-x)S_(x) thin films deposited under 0.14 M thiourea concentration. Therefore, the thin films have better structural, optical and electric properties, and are more suitable for the buffer layers of copper indium gallium selenide(CIGS) thin film solar cells.