Influence of SiO2 layer on the dielectric function of gold nanoparticles on Si substrate
Chen, T. P.
Liu, Y. C.
Yu, S. F.
Date of Issue2011
School of Electrical and Electronic Engineering
The dielectric functions of gold nanoparticle (Au NP) self-assembled on Si substrates without and with a SiO2 layer (3, 10 and 30 nm in thickness) have been examined. For Au NP on Si substrate without a SiO2 layer, a splitting in surface plasmon resonance (SPR) band in the imaginary part of the dielectric function ɛ2 is observed, i.e., besides the typical SPR peak at ∼2 eV, a pronounced peak at ∼1 eV emerges, which is due to the hot spot, that is, a narrow gap between the Au NP and the mirror image. The splitting in the SPR band is greatly suppressed for the 3 nm SiO2 layer and disappears for the 10 nm and 30 nm SiO2 layers, showing that the resonant intensity from the hot spot rapidly attenuates with the gap distance. In addition, the SiO2 layer also has significant influence on the interband transitions of Au NP. These observations are discussed in terms of the image charge effect and the formation of the percolated conductive Au layer on the SiO2 layer.
Electrical and Electronic Engineering
Electrochemical and solid-state letters
© 2011 ECS - The Electrochemical Society. This paper was published in Electrochemical and Solid-State Letters and is made available as an electronic reprint (preprint) with permission of ECS - The Electrochemical Society. The paper can be found at the following official DOI: [http://dx.doi.org/10.1149/2.021201esl]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.