Self-Assembly of Ordered SiO2@Au Core-Shell Nanoparticle Arrays

This paper presents a wet-based self-assembly process for nano-fabricating 1-D arrays of spherical nanoparticles and/or gold-nanoshells with controllable inter-particle distance for near infrared optical communications and for plasmon polariton waveguides featured with the lateral mode size below the optical diffraction limit. The process entails two main procedures. First, the SiO₂ nanoparticle colloidal solution was restricted to flow through the gap between the patterned substrate and the cover slip, and the particles, trapped in the patterned, recessed regions, self-assembled to form closely arranged SiO₂ particle arrays. These SiO₂ particle arrays then acted as a template with which SiO₂@Au nanoshell particle arrays of interest with desirable interparticle distance were obtained by repeating the above procedure with SiO₂@Au dispersed solution. The needed high quality SiO₂@Au core-shell nanoparticles with tunable surface plasma resonance also were synthesized in our laboratory using the seed-and-grow method. Results show that, with this method, the interparticle distance of the nanoshell particle arrays can be controlled by a proper selection of the patterned groove and the sizes of SiO₂ and SiO₂@Au nanoshell particles. As demonstrated by experiment, the method is general and can be applied to obtain nanoparticle particle arrays of other materials with controllable distance.