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Title: Optical thin film formation by gas-cluster ion beam assisted deposition

Journal Article · · AIP Conference Proceedings
DOI:https://doi.org/10.1063/1.59165· OSTI ID:21207973
; ; ; ;  [1]; ; ;  [2]
  1. Ion Beam Engineering Experimental Laboratory, Kyoto University, Sakyo, Kyoto 606-8501 (Japan)
  2. Adachi New Industrial Co. Ltd., ANICS Bldg. 10F, 1-14-20, Itachibori, Nishi-ku, Osaka 550-0012 (Japan)

We have developed a gas cluster ion beam assisted deposition system for high-quality optical thin film formation (SiO{sub 2} and TiO{sub 2} etc.) with high packing density. Cluster ions can transport thousands of atoms per ion with very low energy per constituent atoms. Consequently, densification of films, which is commonly required for optical coatings, can be achieved without the introduction of increased surface roughness and irradiation-induced defects, which are critical issues for conventional ion assisted deposition processes. In this work maximizing the intensity of gas-cluster ion beam current is discussed based upon a few experiments increasing the neutral cluster beam intensity and designing an ionizer for achieving an efficient transportation of the cluster ion beam. As a result, we successfully obtained a high intensity gas-cluster ion current up to {approx}30 {mu}A, which is one order of magnitude larger than that obtained so far. TiO{sub 2} films were grown on Si substrates by electron beam evaporation of TiO{sub 2} at ambient temperature under O{sub 2}-cluster ion bombardment with acceleration energies (V{sub acc}) up to 12 keV. Refractive index, n of the films was increased steeply to n={approx}2.30 above V{sub acc}=4 keV. Water-soaking tests for 12 hrs of the samples revealed that an increase in n values due to moisture absorption becomes smaller with increasing V{sub acc}, which suggests that the films become more dense with increasing V{sub acc} from optical point of view.

OSTI ID:
21207973
Journal Information:
AIP Conference Proceedings, Vol. 475, Issue 1; Conference: 15. international conference on the application of accelerators in research and industry, Denton, TX (United States), 4-7 Nov 1998; Other Information: DOI: 10.1063/1.59165; (c) 1999 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
Country of Publication:
United States
Language:
English