Effects of ion beam mixing on the depth profiles of thin metal layer in TiO2

Thin films of TiO2 prepared by a sol-gel method were irradiated with 100 keV Ar ions. A bilayer (Mo/TiO2) and multilayers (TiO2/Mo,Cr,Ag/TiO2) of the thin metal films and TiO2 were used. After the irradiation, concentration profiles and the structure of the surface layer were studied by Rutherford backscattering spectroscopy (RBS), X-ray photoelectron spectroscopy (XPS) and glancing angle X-ray diffraction (G-XRD). It was found that a ballistic mixing was predominant in the redistribution of Mo and Cr atoms embedded in TiO2, and oxides of Mo and Cr were decomposed in metallic states with increasing ion fluence. In the case of TiO2/Ag/TiO2, Ag colloids were formed in process of a dip-coating of the sol-gel method, and the Ag atoms were dispersed into deeper layer by a grain boundary diffusion. Ion beam mixing in the TiO2 films produced a slight increase in the optical absorption of visible light.