The National Institute of Advanced Industrial Science and Technology’s (AIST) Laboratory for Advanced Optical Technology (LAOtech), directed by Junji Tominaga, has developed a technology for the formation of three-dimensional Ag nanoparticle and nanowire clusters with a uniform diameter of 20-30 nm on a polycarbonate optical disk substrate, by hydrogen-dry-etching of sputtered silver oxide (AgOx) thin film.

Conventional Ag nanoparticle and nanowire production methods involve aggregation of Ag ions in aqueous solution with heating or production of two-dimensional island structures on the substrate surface using a vapor deposition method, followed by heat treatment. However, the application of optical devices using Ag nanoparticles has been limited, because the lack of uniformity in the Ag ion aggregate generation or two-dimensional island structures means a uniform film cannot be formed over a wide area, and the films cannot be produced on the surface of materials with low melting points, such as plastics.

LAOtech at the AIST has developed a method for hydrogen-dry-etching of sputtered AgOx thin film, whereby a uniform layer of 20-30 nm Ag nanoparticles and nanowires can be produced in around 5 minutes at room temperature without heating the substrate on which the AgOx thin film is formed. The method also enables formation of three-dimensional nanoparticles, which is not possible with conventional vacuum deposition techniques. Therefore, the research is expected to have applications in next-generation ultra-high density optical data storage for electromagnetic field-enhanced readouts from nanopits and photonic crystals.

The detailed results from this research are scheduled for presentation at Micro- and Nano-Engineering 2002 (MNE 2002), held in Switzerland between 16 and 19 September 2002.