Cost-effective large-area Ag nanotube arrays for SERS detections: effects of nanotube geometry

Yi-Xiang Yang; Jinn P Chu

doi:10.1088/1361-6528/ac1636

Cost-effective large-area Ag nanotube arrays for SERS detections: effects of nanotube geometry

Nanotechnology. 2021 Sep 1;32(47). doi: 10.1088/1361-6528/ac1636.

Authors

Yi-Xiang Yang¹, Jinn P Chu^{1

2}

Affiliations

¹ Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
² Applied Research Center for Thin-Film Metallic Glass, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.

PMID: 34284366
DOI: 10.1088/1361-6528/ac1636

Abstract

This study demonstrated highly-ordered metallic nanotube arrays (MeNTAs) with a precisely controlled geometric shape to promote surface-enhanced Raman scattering (SERS). Using both simulation and experimental methods, we designed and fabricated MeNTAs with nanotube geometries that possess a large surface area to absorb probe molecules as well as geometric features capable of inducing hot spots for SERS enhancement. The proposed top-down wafer-scale lithographic and sputter-deposition process is a simple and cost-effective approach to the fabrication of 1 mm × 1 mm MeNTA at room temperature. Simulation results of nanotubes with various materials (Au, Ag, and Cu), diameters (100-1500 nm), geometric shapes (circle, equilateral triangle and square) and triangle corner curvatures (ranging from 0 to 300 nm) identified Ag triangles with sharp tips as the geometry best suited to SERS enhancement. The SERS spectra of crystal violet molecules generated from the Ag MeNTAs verified the patterns observed in computational simulations, wherein the effects of MeNTA on SERS decreased with an increase in the size of the nanotubes. Enhancement factor of 1.06 × 10⁹was obtained from our triangular Ag MeNTA, confirming its efficacy as an ultrahigh sensitivity SERS-active substrate.

Keywords: Ag; SERS; crystal violet (CV); enhancing surface-enhanced Raman scattering; metallic nanotube array.