Title: Characterisation of aluminium and alumina thin films coatings using different deposition methods for enhancement of optical properties

Authors: Harinandan Kumar; M. Muralidhar Singh; P. Sivaiah

Addresses: Department of Petroleum and Earth Sciences, University of Petroleum and Energy Studies, Bidholi, Via Prem Nagar, Dehradun, Uttarakhand 248007, India ' Department of Mechanical Engineering, Madanapalle Institute of Technology and Science, P.O. Box 14, Kadiri Road Angallu (V), Madanapalle-517325, Chittoor District, Andhra Pradesh, India ' Department of Mechanical Engineering, Madanapalle Institute of Technology and Science, P.O. Box 14, Kadiri Road Angallu (V), Madanapalle-517325, Chittoor District, Andhra Pradesh, India

Abstract: The enhancement of optical properties such as transmittance, absorptance, and reflectance is possible by applying selective metal and ceramic coatings to the surfaces. Aluminium oxide coatings have potential advantages in this regard. The coating is used for passivation, wear resistance, anti-reflection purpose, etc. in combination with other materials. The aluminium-based coating characteristics include transmittance, reflectance, absorptance, surface roughness, etc. depending on the type of deposition method, operating principles involved, and working conditions maintained during the deposition process. In this study, aluminium and alumina thin films of different thicknesses were deposited on borosilicate glass substrates using thermal evaporation, E-beam, and sputtering method with a substrate temperature from 25°C to 100°C. The optical properties like transmittance, reflectance, and absorptance were evaluated for the thin film coating. The surface roughness of the thin film was also analysed. The Rrms values of aluminium and alumina thin films deposited using thermal evaporation and sputtering process with a coating thickness from 100 nm to 300 nm varied from 2 to 5 nm and 1 nm. An increase in reflectance of aluminium coatings was observed with surface roughness.

Keywords: thin films; aluminium coating; alumina coating; thermal evaporation method; E-beam method; sputtering method.

DOI: 10.1504/IJMATEI.2021.116943

International Journal of Materials Engineering Innovation, 2021 Vol.12 No.3, pp.165 - 187

Received: 11 Sep 2020
Accepted: 05 Nov 2020

Published online: 28 Jul 2021 *

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