Study of textured ZnO:Al thin film and its optical properties for thin film silicon solar cells

The study addresses the optical properties and morphologies of Al-doped ZnO (AZO) films textured by the chemical wet-etching method using three different acid solutions: HCl, HNO₃, and H₃PO₄. An initial AZO film was sputtered on a glass substrate by rf magnetron sputtering. The film surface was then textured by wet-etching using diluted HCl, HNO ₃, or H₃PO₄. The average transmittance of all the post-treated ZnO:Al films remains around 7580% as measured by a UVvis analyzer. A haze ratio calculation shows that the light scattering properties can be significantly controlled by varying the etchant species, acid concentration, and etching time. Further, the HNO₃ etchant gives the highest haze ratio of 43.0% at a wavelength of 550 nm. Compared with solar cells deposited on non-textured ZnO:Al films, a significant enhancement in the short-circuit current density of 17.8% for the a-Si solar cells with textured ZnO:Al films was achieved.