Microstructure of TiO2 and ZnO films fabricated by the sol-gel method

Titanium dioxide and zinc oxide films were fabricated by spin-on and dip-coating methods. Both types of films exhibited columnar grains when the single coating was thin, similar to 10 nm. The columnar TiO2 films were dense, as confirmed by their density values calculated from the refractive index and TEM results, The addition of Al cations into the ZnO suppressed grain growth, because Zn had a lower diffusivity in the doped films, The doped ZnO films had nearly the same electrical resistivity as that of the undoped films.