Improving the optical and crystalline properties on CdS thin films growth on small and large area by using CBD technique

Abstract

CdS polycrystalline thin films have been used as window layer in solar cells; the optical and crystalline quality of the CdS-partner plays an important role in the photovoltaic device performance. CdS thin films were deposited by using Chemical Bath Deposition (CBD). The SnO$_2$:F substrates used were chemically treated with HCl (0.1M) and others were thermally annealed in different atmospheres (Ar y O$_2$). The physical properties of CdS thin films were influenced by the HCl treatment, position, size and the substrates movement inside the reaction beaker. The CdS samples were deposited in areas of 4 cm$^2$, 50 cm$^2$ and 100 cm$^2$. Finaly CdS thin films with thickness of 35-300~nm with good optical and crystalline quality on a uniform morphology were obtained. Transmittance values were obtained for all samples about 85-90% with an average of gap energy of 2.5 eV.