Ag fractals formed on top of a porous TiO2 thin film

Abstract

This work demonstrates the formation of Ag fractals on top of a Ag:TiO2 thin film. The dendrite-type objects emerged from a homogeneous and highly transparent Ag:TiO2 nanocomposite, via the mechanism of diffusion-limited-aggregation of Ag atoms, during heat-treatment at 500 ºC. A porous TiO2 matrix was also formed during this process, opening a wide range of possible applications, namely in sensing-based ones, together with surface enhanced spectroscopies. Furthermore, fractals incorporate a wide range of shapes and spatial scales, inducing a potentially interesting optical response, over the whole visible range, presumably related with localized surface plasmon modes with very broad spectral distribution.