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Proceedings Paper

Infrared transparent conductive coatings deposited by activated reactive evaporation
Author(s): Orna Marcovitch; Hedva Zipin; Zeev Klein; Iftah Lubezky
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Paper Abstract

Infrared transparent conductive coatings were developed for ZnS substrates. The conductive layer was an indium oxide film deposited in a reactive atmosphere consisting of low energy oxygen ions. Activation of the gas molecules was performed by an ion source of the hollow cathode type. The deposited films were characterized by their transparency, conductivity and environmental durability. It was found that the positioning of the ion source relative to the substrates was critical for the film properties. High transmission and low sheet resistance of the film were obtained by optimization of the evaporation parameters which included oxygen pressure, cathode current, deposition rate, film thickness and substrate temperature. Application of the conductive film for both 3-5jim and 8-12im infrared atmospheric windows was possible. The transmission of the indium oxide film depend on the infrared free carriers absorption and the reflections at the substrate and air interfaces. Improvement of the optical performance was accomplished by depositing antireflective and induced transmission dielectric stacks. Several dielectric stacks were designed and matched to indium oxide layers of 50Q/sq and 30Q/sq sheet resistance for maximum transmission, either at a single wavelength or for a wide band in the 3-5pm and 8-11.5pm spectral regions. Typical average transmittance values of ZnS substrates coated with conductive stacks were 82% and 7L% in the 3-5pm region and 77% and 63% in the 8-'l2pm region for sheet resistances of 50Q/sq and 30Q/sq, respectively. At 1O.5pm peak transmittance values higher than 80% were obtained. The coatings were durable and passed adhesion, humidity and moderate abrasion tests in accordance with MIL-C--675C.

Paper Details

Date Published: 1 April 1991
PDF: 1 pages
Proc. SPIE 1442, 7th Mtg in Israel on Optical Engineering, (1 April 1991); doi: 10.1117/12.49045
Show Author Affiliations
Orna Marcovitch, Rafael (Israel)
Hedva Zipin, Rafael (Israel)
Zeev Klein, Rafael (Israel)
Iftah Lubezky, Rafael (Israel)

Published in SPIE Proceedings Vol. 1442:
7th Mtg in Israel on Optical Engineering
Moshe Oron; Itzhak Shladov, Editor(s)

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