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Journal of Materials Science

, Volume 43, Issue 18, pp 6159–6166 | Cite as

Formation of nano-columnar amorphous carbon films via electron beam irradiation

  • Tatsuhiko AizawaEmail author
  • E. Iwamura
  • T. Uematsu
Article

Abstract

Electrical beam (EB) irradiation is used to chemically modify the amorphous carbon film, a-C:H, which is prepared by the DC magnetron sputtering. The starting a-C:H film has vague columnar structure with lower density intercolumns as predicted by Thornton structure model. The EB-irradiated a-C:H film has fine nano-columnar structure with the average columnar size of 10–15 nm. This size is equivalent to the measured in-plain correlation length by the Raman spectroscopy. Little change in the sp2/sp3 bonding ratio is observed in the columnar matrix before and after EB-irradiation. Increase of sp2/sp3 ratio is noted in the intercolumns of irradiated a-C:H films. No change is detected in the hydrogen content of a-C:H films before and after EB-irradiation: 35 at% hydrogen in a-C:H. Increase of the in-plain density via EB-irradiation, is attributed to the increase of local atomic density in the intercolumns, which is measured by the electron energy zero-loss spectroscopy. This local densification is accompanied with ordering or graphitization in the intercolumns of the EB-irradiated a-C:H film. The nano-columnar a-C:H film modified by EB-irradiation has non-linear elasticity where indentation displacement should be reversible up to 8% of film thickness. Owing to this ordering and densification via EB-irradiation, softening both in stiffness and hardness takes place with increasing the irradiation time.

Keywords

Hydrogen Content Amorphous Carbon Bonding State Electron Beam Irradiation Bonding Ratio 

Notes

Acknowledgement

Authors would like to express their gratitude to Mr. T. Fukuda and Mr. H. Morishita, R & D center, Mitsue Die and Mold Co. Ltd. for experimental help in use of Raman spectroscopy.

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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.AsiaSEED-InsituteTokyoJapan
  2. 2.Japan R&D LaboratoryUniversity of TorontoOta-CityJapan
  3. 3.Arakawa Chemical Co. Ltd.OsakaJapan
  4. 4.Tokyo Metropolitan Industrial Research InstituteOta-CityJapan

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