Article

2020; 20(3): 391-399

Published online January 7, 2020 https://doi.org/10.1016/j.cap.2019.12.005

Copyright © The Korean Physical Society.

FDTD simulation of the optical properties for a gold nanoparticle-over-nanosheet hybrid structure

Chen Y., Wang J., Xu T., Liu M., Liu J., Huang H., Ouyang F.

School of Physics and Electronics, and Institution of Super-microstructure and Ultrafast Process in Advanced Materials, Central South University, Changsha, 410083, China; Powder Metallurgy Research Institution and State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, China

Correspondence to:Chen, Yu
Physics, Central South University

Received: October 14, 2019; Accepted: December 18, 2019

Abstract

The optical properties of a two-dimensional gold nanoparticle-over-nanosheet (2D-AuNP/NS) have been studied using Finite-Difference Time-Domain (FDTD) method. 2D-AuNP/NS hybrid structure exhibits three typical localized surface plasmon (LSP) resonances, which occur in nanogaps between NP-NP, NP-NS and coupled upper and lower surface of NS respectively. Thus, the influence of AuNP-size, surface AuNP-coverage, NP-NP-spacing and NS-thickness on the localized electric field was analyzed in details. The LSP resonance between NP-NS has been predicted to be the most important effect on SERS, which is dominant, stable and can maintain the SERS intensity even at a relatively low NP-coverage. If a slight deviation of AuNPs away from their original periodic positions was permitted, a disordered model was then constructed which would more closely approximate the real AuNP/NS hybrid structure and was able to calculate the influence of disorder on LSP resonance. A blue shift (rather than red shift) of the resonance peak was observed and its peak intensity would increase first and decrease then with the increase of NP-NP-spacing. FDTD simulations have finally illustrated that NP-coverage should be controlled ranging from 80.0 % to 87.0% or just equal to 100%, if both AuNP-size and NP-thickness is controlled to 10 nm. The FDTD simulation results are qualitative agreement with the existing experimental data and are very useful in the future materials designs for AuNS-based nanocomposite. © 2019

Keywords: Finite-Difference Time-Domain, Gold nanoparticle-over-nanosheet, Gold nanosheet, Surface-enhanced Raman scattering

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