Optical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications

Abstract Copper oxide films hold substantial promise as anti-stiction coatings in micro-electromechanical (MEMS) devices and with shrinking dimensions on the nanometre scale on nano electromechanical (NEMS) devices. The Hamaker constant will play a very significant role in understanding stiction and...

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Autores principales:	Abraham Ogwu, T. H. Darma
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/b91f70ee719f404f8ce7e9a80e1ed8c4
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spelling	oai:doaj.org-article:b91f70ee719f404f8ce7e9a80e1ed8c42021-12-02T14:21:43ZOptical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications10.1038/s41598-021-83653-82045-2322https://doaj.org/article/b91f70ee719f404f8ce7e9a80e1ed8c42021-02-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-83653-8https://doaj.org/toc/2045-2322Abstract Copper oxide films hold substantial promise as anti-stiction coatings in micro-electromechanical (MEMS) devices and with shrinking dimensions on the nanometre scale on nano electromechanical (NEMS) devices. The Hamaker constant will play a very significant role in understanding stiction and tribology in these devices. We used an approximate but sufficiently accurate form of the Lifshitz theory using the multiple oscillator model to calculate the Hamakers constant of symmetric copper oxide thin films based on experimentally obtained dielectric data in the wavelength range 190-850 nm using spectroscopic ellipsometry. We also used the Tabor–Winterton approximation (TWA) and Surface energy measurements to determine the Hamaker constant. There was better agreement in the Hamaker constant values obtained by the limited Lifshitz theory and TWA approach than with the Surface energy approach. The difference is explained through the influence of surface roughness on the surface energy using extensions of the stochastic KPZ growth model and the Family-Vicsek scaling relation and rigorous treatment of the Cassie-Baxter and Wenzel models as optimisations of a surface free energy functional linking roughness and surface tension. The dominance of the Cu2O phase in the films and of the London dispersion force on the surface of the films was previously confirmed by FTIR Cu(I)–O vibrational mode observation and XPS Cu 2p 3/2 binding energy peak and its fitted satellites. The use of the limited Lifshitz theory and ellipsometry data would seem to provide a suitable best first approximation for determining the Hamaker constant of predominantly dispersive anti-stiction coatings in technologically important MEMS/NEMS devices.Abraham OgwuT. H. DarmaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-11 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Abraham Ogwu T. H. Darma Optical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications
description	Abstract Copper oxide films hold substantial promise as anti-stiction coatings in micro-electromechanical (MEMS) devices and with shrinking dimensions on the nanometre scale on nano electromechanical (NEMS) devices. The Hamaker constant will play a very significant role in understanding stiction and tribology in these devices. We used an approximate but sufficiently accurate form of the Lifshitz theory using the multiple oscillator model to calculate the Hamakers constant of symmetric copper oxide thin films based on experimentally obtained dielectric data in the wavelength range 190-850 nm using spectroscopic ellipsometry. We also used the Tabor–Winterton approximation (TWA) and Surface energy measurements to determine the Hamaker constant. There was better agreement in the Hamaker constant values obtained by the limited Lifshitz theory and TWA approach than with the Surface energy approach. The difference is explained through the influence of surface roughness on the surface energy using extensions of the stochastic KPZ growth model and the Family-Vicsek scaling relation and rigorous treatment of the Cassie-Baxter and Wenzel models as optimisations of a surface free energy functional linking roughness and surface tension. The dominance of the Cu2O phase in the films and of the London dispersion force on the surface of the films was previously confirmed by FTIR Cu(I)–O vibrational mode observation and XPS Cu 2p 3/2 binding energy peak and its fitted satellites. The use of the limited Lifshitz theory and ellipsometry data would seem to provide a suitable best first approximation for determining the Hamaker constant of predominantly dispersive anti-stiction coatings in technologically important MEMS/NEMS devices.
format	article
author	Abraham Ogwu T. H. Darma
author_facet	Abraham Ogwu T. H. Darma
author_sort	Abraham Ogwu
title	Optical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications
title_short	Optical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications
title_full	Optical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications
title_fullStr	Optical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications
title_full_unstemmed	Optical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications
title_sort	optical and surface energy probe of hamaker constant in copper oxide thin films for nems and mems stiction control applications
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/b91f70ee719f404f8ce7e9a80e1ed8c4
work_keys_str_mv	AT abrahamogwu opticalandsurfaceenergyprobeofhamakerconstantincopperoxidethinfilmsfornemsandmemsstictioncontrolapplications AT thdarma opticalandsurfaceenergyprobeofhamakerconstantincopperoxidethinfilmsfornemsandmemsstictioncontrolapplications
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Optical and surface energy probe of Hamaker constant in copper oxide thin films for NEMS and MEMS stiction control applications

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