Next Article in Journal
Improvement of Corrosion Resistance of Hastelloy-N Alloy in LiF-NaF-KF Molten Salt by Laser Cladding Pure Metallic Coatings
Previous Article in Journal
Capturing the Competing Influence of Thermal and Mechanical Loads on the Strain of Turbine Blade Coatings via High Energy X-rays
Previous Article in Special Issue
Interconnections between Electronic Structure and Optical Properties of Multilayer Nanolaminate TiAlN/Ag and Al2O3/Ag Coatings
Article Menu
Issue 9 (September) cover image

Export Article

Open AccessArticle
Coatings 2018, 8(9), 321; https://doi.org/10.3390/coatings8090321

On the Effect of Thin Film Growth Mechanisms on the Specular Reflectance of Aluminium Thin Films Deposited via Filtered Cathodic Vacuum Arc

1
Physics of Surfaces and Materials, IK4-TEKNIKER, 20600 Eibar, Spain
2
Department of Applied Physics, University of Salamanca, 37008 Salamanca, Spain
3
Functional Surfaces and Nanostructures, Profactor GmbH, Im Stadtgut A2, 4407 Steyr-Gleink, Austria
4
Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
5
Department of Materials Science, Metallurgical Engineering and Inorganic Chemistry, IMEYMAT, University of Cadiz, 11510 Puerto Real, Spain
*
Author to whom correspondence should be addressed.
Received: 31 July 2018 / Revised: 10 September 2018 / Accepted: 12 September 2018 / Published: 13 September 2018
(This article belongs to the Special Issue Surface Engineering and Nanofilms)
Full-Text   |   PDF [5226 KB, uploaded 13 September 2018]   |  

Abstract

The optimisation of the specular reflectance of solar collectors is a key parameter to increase the global yield of concentrated solar power (CSP) plants. In this work, the influence of filtered cathodic vacuum arc deposition parameters, particularly working pressure and deposition time, on the specular and diffuse reflectance of aluminium thin films, was studied. Changes in specular reflectance, measured by ultraviolet–visible and near-infrared spectroscopy (UV-vis-NIR) spectrophotometry, were directly correlated with thin film elemental concentration depth profiles, obtained by Rutherford backscattering spectrometry (RBS), and surface and cross-sectional morphologies as measured by scanning electron microscopy (SEM) and profilometry. Finally, atomic force microscopy (AFM) provided information on the roughness and growth mechanism of the films. The two contributions to the total reflectance of the films, namely diffuse and specular reflectance, were found to be deeply influenced by deposition conditions. It was proven that working pressure and deposition time directly determine the predominant factor. Specular reflectance varied from 12 to 99.8% of the total reflectance for films grown at the same working pressure of 0.1 Pa and with different deposition times. This transformation could not be attributed to an oxidation of the films as stated by RBS, but was correlated with a progressive modification of the roughness, surface, and bulk morphology of the samples over the deposition time. Hence, the evolution in the final optical properties of the films is driven by different growth mechanisms and the resulting microstructures. In addition to the originally addressed CSP applications the potential of the developed aluminium films for other application rather than CSP, such as, for example, reference material for spectroscopic diffuse reflectance measurements, is also discussed. View Full-Text
Keywords: filtered cathodic vacuum arc; total and specular reflectance; thin film deposition conditions; structural characterisation filtered cathodic vacuum arc; total and specular reflectance; thin film deposition conditions; structural characterisation
Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Rincón-Llorente, G.; Heras, I.; Guillén Rodríguez, E.; Schumann, E.; Krause, M.; Escobar-Galindo, R. On the Effect of Thin Film Growth Mechanisms on the Specular Reflectance of Aluminium Thin Films Deposited via Filtered Cathodic Vacuum Arc. Coatings 2018, 8, 321.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Coatings EISSN 2079-6412 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top