Engineering Au Nanoparticle Arrays on SiO2 Glass by Pulsed UV Laser Irradiation

K Grochowska,A Iwulska,N Nedyalkov,P Atanasov,G Obara,M Sawczak,G Śliwiński,M Obara

doi:10.1007/s11468-012-9428-3

Abstract

We study semi-regular arrays of Au nanoparticles (NP) obtained via UV laser irradiation of thin Au films on glass substrate. The NP structures are prepared from films of a thickness up to 60 nm produced by discharge sputtering or pulsed laser deposition, and annealed by nanosecond laser pulses at 266 or 308 nm, respectively, at fluencies in the range of 60–410 mJ/cm2. For the rare- and close-packed NP structures, consistent description of optical properties is derived from microscopic observation, measurements of the absorption, and Raman spectra, and modeling of the near-field intensity distributions. The absorption bands centered at 540–570 nm are ascribed to resonant absorption of the surface plasmons. For the band positions, half widths, and intensities, the dependence on the NP shape (partial spheres), size, size distribution, and also excitation energy is observed. The structures are characterized by markedly reduced dephasing times of ∼3 fs. It is shown, that laser annealing of thin Au films provides reliable and cost effective method for controlled preparation of semi-regular NP arrays favorable for photonic applications.

Highlights

Optical properties of gold nanoparticles evoke much interest due to their potential nonlinear applications such as light harvesting, optical tweezers, and ultrasensitive detection
For the thin films deposited on glass substrates by both the sputtering and pulsed laser deposition (PLD) techniques, the uniform, fine-grained polycrystalline structures were deduced from SEM images
No film discontinuities and other surface defects were noticed. This indicates that such films as base material for nanostructuring when produced under similar conditions and at the same deposition rates are of similar structure and properties

Summary

Introduction

Optical properties of gold nanoparticles evoke much interest due to their potential nonlinear applications such as light harvesting, optical tweezers, and ultrasensitive detection. Gold represents one of the most preferred materials because of large enhancement of the local field provided under irradiation in the visible and near-infrared part of the spectrum, high stability of the structures, biocompatibility, corrosion resistance, and sufficiently matured preparation techniques of nanoparticles (NPs) [3,4,5]. The NP structures produced by techniques based on the thin film annealing seem to be advantageous compared to deposited by the electron or ion beam lithography, chemically or colloidal ones. This is confirmed by comparative studies showing that annealing ensures controllable process performance and results in agglomerate-free NP structures of tunable properties [6,7,8,9]. A number of works confirm that this technique is sufficiently flexible to provide conclusive research data and offers unexplored application potential, too [9, 11,12,13]

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