Plasmonic properties of gold nanoparticle arrays fabricated using a sequential dewetting process

A scalable, cost-effective technique to fabricate ordered gold nanoparticle arrays with fine control over nanoparticle size and interparticle distance is presented. The array is grown in the pores of an anodic aluminum oxide membrane by the solid-state dewetting process. Control over the nanoparticle size and spacing between particles was achieved by sequential metal deposition and annealing processes, yielding nanoparticles with diameters (D) ranging from 50 to 70 nm and corresponding interparticle distances ranging from 12 to 30 nm. The advantage of this technique is that the nanoparticle size, spherical shape, and hexagonal close-packed ordering of the array can be precisely controlled, allowing for fine tuning of the plasmonic absorption properties. The important parameters that determine the size, shape, and distribution of nanoparticles in the array are the template morphology (dimple geometry) and the thickness of the evaporated metal layer. Above a certain critical film thickness, the nanoparticles coalesce to form nano-islands. The significance of this work is that it provides a reliable technique to assemble metal nanoparticles into high density arrays, with good control over particle shape and distribution. Such arrays can be used to generate highly concentrated electromagnetic fields for plasmonic sensor applications.