Zinc-indium-oxide sol-gel thin film: surface patterning, morphology and photocatalytic activity

We report the fabrication of surface patterned zinc indium oxide thin films by pressure assisted capillary force lithography from the precursor solutions of varying indium content (55% maximum). The presence of various morphologies (spherical, hexagonal plate, cotton ball, flower-and island-like) of hexagonal ZnO together with the formation of light surface patterns was observed from electron microscopes (field emission scanning electron microscope, TEM) for the films deposited from the precursors of <= 45% indium. However, at 55% indium (ZI55), the development of high fidelity surface patterns (average periodicity similar to 1.5 mu m; peak height similar to 15 nm) was observed from atomic force microscopy (AFM) study. A gradual increase in photocatalytic activity (PA) of the films towards decomposition of rhodamine 6G dye under UV (254 nm) was found on increasing indium content. Moreover, an improvement of the PA over 13 times was noticed by nano-Au coating on ZI55. This fabrication strategy could be used for PA improvement of metal oxide semiconductors.