Optimization of Au:CuO thin films by plasma surface modification for high-resolution LSPR gas sensing at room temperature

In this study, thin films composed of gold nanoparticles embedded in a copper oxide matrix (Au:CuO), manifesting Localized Surface Plasmon Resonance (LSPR) behavior, were produced by reactive DC magnetron sputtering and post-deposition in-air annealing. The effect of low-power Ar plasma etching on t...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2022-09, Vol.22 (18), p.7043
Main Authors: Proença, Manuela, Rodrigues, Marco S., Meira, Diana I., Castro, M. Cidalia R., Rodrigues, Pedro V., Machado, A. V., Alves, Eduardo, Barradas, Nuno P., Borges, Joel, Vaz, F.
Format: Article
Language:English
Subjects:
Annealing
Argon plasma
Au nanoparticles
Ciências Físicas
Ciências Naturais
Copper oxide
Copper oxides
Cuprite
Dielectric films
Dielectric properties
Gas sensors
Gases
Gold
high-resolution LSPR spectroscopy
Magnetron sputtering
Metal oxides
Microscopy
Nanocomposites
nanostructural evolution
optical gas sensing
Optical properties
Plasma etching
plasmonics
Room temperature
Science & Technology
Sensors
Surface properties
Thin films
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Summary:In this study, thin films composed of gold nanoparticles embedded in a copper oxide matrix (Au:CuO), manifesting Localized Surface Plasmon Resonance (LSPR) behavior, were produced by reactive DC magnetron sputtering and post-deposition in-air annealing. The effect of low-power Ar plasma etching on the surface properties of the plasmonic thin films was studied, envisaging its optimization as gas sensors. Thus, this work pretends to attain the maximum sensing response of the thin film system and to demonstrate its potential as a gas sensor. The results show that as Ar plasma treatment time increases, the host CuO matrix is etched while Au nanoparticles are uncovered, which leads to an enhancement of the sensitivity until a certain limit. Above such a time limit for plasma treatment, the CuO bonds are broken, and oxygen is removed from the film’s surface, resulting in a decrease in the gas sensing capabilities. Hence, the importance of the host matrix for the design of the LSPR sensor is also demonstrated. CuO not only provides stability and protection to the Au NPs but also promotes interactions between the thin film’s surface and the tested gases, thereby improving the nanocomposite film’s sensitivity. The optimized sensor sensitivity was estimated at 849 nm/RIU, which demonstrates that the Au-CuO thin films have the potential to be used as an LSPR platform for gas sensors. This research was sponsored by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020 and by the project CO2Plasmon with reference EXPL/CTM-REF/0750/2021. M.P. acknowledges her Ph.D. Scholarship from FCT, with reference SFRH/BD/137076/2018. Diana I. Meira acknowledges her Ph.D. Scholarship from FCT, with reference SFRH/BD/143262/2019.
ISSN:1424-8220
1424-8220
DOI:10.3390/s22187043