Abstract

Periodic noble metal nanoparticles offer a wide spectrum of applications including chemical and biological sensors, optical devices, and model catalysts due to their extraordinary properties. For sensing purposes and catalytic studies, substrates made of glass or fused-silica are normally required as supports, without the use of metallic adhesion layers. However, precise patterning of such uniform arrays of silica-supported noble metal nanoparticles, especially at sub-100 nm in diameter, is challenging without adhesion layers. In this paper, we report a robust method to large-scale fabricate highly ordered sub-20 nm noble metal nanoparticles, i.e., gold and platinum, supported on silica substrates without adhesion layers, combining displacement Talbot lithography (DTL) with dry-etching techniques. Periodic photoresist nanocolumns at diameters of ~110 nm are patterned on metal-coated oxidized silicon wafers using DTL, and subsequently transferred at a 1:1 ratio into anti-reflection layer coating (BARC) nanocolumns with the formation of nano-sharp tips, using nitrogen plasma etching. These BARC nanocolumns are then used as a mask for etching the deposited metal layer using inclined argon ion-beam etching. We find that increasing the etching time results in cone-shaped silica features with metal nanoparticles on the tips at diameters ranging from 100 nm to sub-30 nm, over large areas of 3×3 cm2. Moreover, subsequent annealing these sub-30 nm metal nanoparticle arrays at high-temperature results in sub-20 nm metal nanoparticle arrays with ~1010 uniform particles.

Highlights

  • Noble metal nanoparticles (NPs) have been studied intensively due to their widespread applications in both academic research and industry

  • We report and demonstrate a robust fabrication method that allows rapid patterning of highly ordered noble metal (Au and Pt) nanoparticles supported on oxidized silicon substrates, without the need of metallic adhesion layers

  • Well-defined and highly ordered bottom anti-reflection layer coating (BARC) nanocolumns with a high uniformity in the height and diameter were obtained over the large area of 3×3 cm[2] (Supplementary Figures S1–S3 and Table S1)

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Summary

Introduction

Noble metal nanoparticles (NPs) have been studied intensively due to their widespread applications in both academic research and industry. The most compelling optical property of metallic NPs is their localized surface plasmon resonance (LSPR)[3]. When excited by incident light, the conduction electrons in metallic NPs are stimulated to collectively oscillate at a resonant frequency, absorbing the incident light at a specific wavelength. By manipulating this LSPR property of metallic NPs, especially in an ordered arrangement, various applications have been demonstrated including optical devices[4], chemical and biological sensors[5,6], fuel and solar cells[7,8], and surface-enhanced Raman spectroscopy (SERS)[9], showing the great benefits of using noble metal-NP arrays.

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