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Dielectric function of sub-10 nanometer thick gold films

Ze Mei, Shuo Deng, Lijie Li Orcid Logo, Xiaoyan Wen, Haifei Lu, Min Li

Applied Physics A, Volume: 127, Issue: 6

Swansea University Author: Lijie Li Orcid Logo

Abstract

A smooth gold (Au) film with thickness below 10 nanometer (nm) is hard to fabricate as well as to accurately measure its thickness and the corresponding dielectric function. Here, we report 5.4, 6.6 and 7.5 nm thick continuous Au films prepared on Chromium (Cr) seed layer. The thickness and dielectr...

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Published in: Applied Physics A
ISSN: 0947-8396 1432-0630
Published: Springer Science and Business Media LLC 2021
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa56933
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Abstract: A smooth gold (Au) film with thickness below 10 nanometer (nm) is hard to fabricate as well as to accurately measure its thickness and the corresponding dielectric function. Here, we report 5.4, 6.6 and 7.5 nm thick continuous Au films prepared on Chromium (Cr) seed layer. The thickness and dielectric function of the Au films are obtained using spectroscopic ellipsometry and first principles calculation. From the fitting results of the ellipsometric parameters, the value of the real part of dielectric function (ε1) is negative almost in the whole spectrum region indicating that the Au films are continuous. For the imaginary part of dielectric function (ε2), it decreases with increasing of the Au film thickness because the surface electrons scattering decreases. Moreover, the calculated and measured results of 5.4, 6.6 and 7.5 nm thick Au films present a good agreement in the wavelength range from 400 to 1600 nm. From the results of the first principles calculation, both ε1 and ε2 decrease with increasing of the Au film thickness. These precise measurement and calculation results of dielectric function are beneficial to nano-photoelectronic devices design with sub-10 nm Au films involved.
Keywords: Sub-10 nm thick au flm; Dielectric function; Spectroscopic ellipsometry; First principles calculation
College: Faculty of Science and Engineering
Issue: 6