Template-directed dewetting of a gold membrane to fabricate highly SERS-active substrates

Abstract

Highly SERS-active substrates can be prepared by heating a discontinuous gold film (thickness about 5 nm) on ordered bowl templates. Nanoparticles (about 20 nm) will uniformly locate on the inner surface of the bowls with an interparticle distance of about 5 nm after heating the discontinuous gold membrane, which is quite different from the morphology of annealing a continuous gold film (>10 nm) (a nanodot array will be obtained in this case). The dewetting process for continuous and discontinuous gold films is discussed. The main difference between the dewetting processes of continuous and discontinuous gold membranes on bowl templates are the hole nucleation sites. For a continuous gold membrane, hole nucleation first takes place at the edge of the bowl. However, hole nucleation emerges uniformly in the discontinuous gold film. This study deepens our understanding of the influence of film thickness on the dewetting process.