Photo-electrochemical deposition of platinum on TiO2 with resolution of twenty nanometers using a mask elaborated with electron-beam lithography

We report the patterning of Pt on a TiO2-rutile single crystal (the fundame ntal absorption band starts at 396 nm) by direct deposition from a water so lution of H2PtCl6 (10-20 mmol/dm(3)) using laser beam writing at 390-396 nm , or by Hg-lamp illumination (i-line at 365 nm). Pt deposition was corrobor ated by microchemical analysis. A resolution of the Pt patterning down to 2 0-30 nm was achieved. To create a Pt pattern with resolution of twenty nano meters. we employed a mask elaborated with electron-beam (EB) drawing litho graphy. The mask was transparent to the writing illumination. The Pt was re duced from the solution by laser beam scanning over resist-covered regions, while the pattern was formed in the openings of the resist. Separation of the growth and illumination regions, typically, by 0.5-2 mum, facilitates t he deposition of reproducible, high-aspect-ratio patterns. It is demonstrat ed that Pt was deposited through a process of diffusion of the light-excite d carriers. The possibility of fabrication of a three-dimensional Pt patter n by the overgrowth of the resist is discussed.