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Título
On the Effect of Thin Film Growth Mechanisms on the Specular Reflectance of Aluminium Thin Films Deposited via Filtered Cathodic Vacuum Arc
Autor(es)
Materia
Surface engineering
Filtered cathodic vacuum arc
Total and specular reflectance
Thin film deposition conditions
Structural characterisation
Fecha de publicación
2018-09-13
Editor
MDPI
Citación
Rincón-Llorente, G.; Heras, I.; Guillén Rodríguez, E.; Schumann, E.; Krause, M.; Escobar-Galindo, R. (2018). On the Effect of Thin Film Growth Mechanisms on the Specular Reflectance of Aluminium Thin Films Deposited via Filtered Cathodic Vacuum Arc. Coatings, 8, 321.
Resumen
[EN]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]
URI
ISSN
2079-6412
DOI
10.3390/coatings8090321
Versión del editor
Colecciones
- GIOETFE. Artículos [48]