Nanofabrication of gold particles in glass films by AFM-assisted local reduction

Gold (Au) nanoparticles were fabricated in thin glass films by a sol-gel process and atomic force microscopy (AFM). Using a conductive AFM cantilever, local reduction of Au(III) ions doped in a dip-coated silica/titania gel film generated Au particles embedded at a certain position of the film. The size of the particles were controlled by the voltages applied between the cantilever and an indium-tin oxide coated glass substrate. Scanning the biased cantilever produced Au particles dispersing in the scan area which exhibited a visible absorption spectrum corresponding to the typical surface plasmon band of nanometer scale Au particles. Further scanning resulted in Au clusters heaped up at the scan area, which gave a red-shifted absorption band due to aggregation.