Low-emittance copper-coating system using atomic-layer-deposited aluminum oxide

•First thermal radiative measurement of copper with thin-film aluminum oxide coating.•Thin-film aluminum oxide coating preserves the low thermal emissivity of copper.•Analysis of dielectric thin-film coating on highly reflective metallic surfaces. Copper, due to its unique properties, has a huge tec...

Full description

Saved in:
Bibliographic Details
Published in:Thin solid films 2022-05, Vol.749, p.139179, Article 139179
Main Authors: Nyman, Leo, Frolec, Jiří, Pudas, Marko, Králík, Tomáš, Musilová, Věra, Kallio, Esa
Format: Article
Language:English
Subjects:
Atomic layer deposition
Copper
Cryogenics
Emissivity
Nanophotonics
Spacecraft
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:•First thermal radiative measurement of copper with thin-film aluminum oxide coating.•Thin-film aluminum oxide coating preserves the low thermal emissivity of copper.•Analysis of dielectric thin-film coating on highly reflective metallic surfaces. Copper, due to its unique properties, has a huge technological importance to our society. However, the oxidation of copper remains an issue in numerous application areas. This is especially the case in visible and IR-band optics, where even minuscule oxide layers degrade the thermo-optical properties of copper surfaces. A solution possibly resides in the application of protective coatings, which can simultaneously impair the low thermal emittance of bare copper surfaces. The present paper examines the use of thin Al2O3 layers as a protective coating for copper. Al2O3 layers with thickness of 4.5, 9.1, 18.5 or 28.3 nm were deposited on polished copper discs using atomic layer deposition (ALD). The total hemispherical emissivity and absorptivity of these coated copper discs were measured from 20 K up to room temperature. The emissivity and absorptivity of the copper with ALD-deposited Al2O3 layers increased with rising temperature and layer thickness. Nonetheless, the observed values stayed below 1.8%, allowing the use of the coated copper in systems where low emission or absorption of thermal radiation is needed. Alongside the experiments, we present a computer-based analysis and interpretation, which may be generally applied for prediction of temperature-dependent emittance of metallic surfaces coated with a thin polar dielectric layer.
ISSN:0040-6090
1879-2731
DOI:10.1016/j.tsf.2022.139179