Pulsed laser deposition of plasmonic-metal nanostructures

Abstract

Pulsed laser deposition (PLD) is shown to be highly effective for growing plasmonic metal nanoparticle (PMN) films exhibiting strong surface plasmon resonance (SPR) under different process parameters. For PLD of PMN films the threshold fluences of ablation for the commonest plasmonic metals such as gold and silver are found to be in the range 1.3–1.6 J cm−2 using a KrF excimer laser. It is also found that the PLD-grown metal nanoparticle films generally have high packaging density of the nanoparticles, typically in the range 1010–1011 particles cm−2, which makes particles' shapes, particle–particle and particle–substrate interactions significant parameters for the ensuing plasmonic properties. The PLD is also shown to be a viable methodology of growing silver/gold alloy nanoparticle plasmonic films. The morphological and compositional characteristics of the metals and their alloy nanoparticle films are found to be controllable by the deposition parameters such as laser fluence, number of laser ablation pulses, target-to-substrate distance, substrate temperature and the gaseous ambience during the PLD or by the post-growth thermal annealing. These morphological and compositional characteristics in turn influence the plasmonic responses of the metal nanoparticle films, which enable one to vary the SPR wavelength typically in the spectral range of about 400–750 nm. The PMNs embedded in different dielectric layers with tuneable plasmon resonance characteristics, which can be grown effectively using PLD, appear to hold significant potential for the future photonic, photovoltaic and biomedical applications.