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Title: Structural order in near-frictionless diamond-like carbon films probed at three length scales in the transmission electron microscope.

Abstract

A series of hydrogenated diamondlike carbon films grown using plasma-enhanced chemical-vapor deposition is systematically studied as a function of source gas composition using transmission electron microscopy. The structure of the films is examined at three distinct length scales. Both plan-view and cross-sectional studies are undertaken to reveal any large-scale inhomogeneities or anisotropy in the films. The degree of medium-range order in the films is measured by performing fluctuation electron microscopy on the plan-view and cross-sectional specimens. Electron-energy-loss spectroscopy is employed to measure the mass density and sp{sup 2}:sp{sup 3} carbon bonding ratios of the samples. Thus, inhomogeneity as a function of depth in the film is revealed by the measurements of the short- and medium-range orders in the two different sample geometries. Soft, low-density diamondlike carbon films with low coefficients of friction are found to be more homogeneous as a function of depth in the film and possess reduced medium-range order in the surface layer. We find that these properties are promoted by employing a high hydrogen content methane and hydrogen admixture as the growth ambient. In contrast, harder, denser films with higher coefficients of friction possess a distinct surface layer with a relatively elevated level of carbon sp{sup 3}more » bonding and a higher degree of medium-range order. The structure of the films is examined in the light of the energetics of the growth process. It appears that a high flux of penetrating hydrogen ions modifies the surface layer containing the remnant damage from the carbon ions, homogenizing it and contributing to a lowering of the coefficient of friction.« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
948794
Report Number(s):
ANL/MSD/JA-58390
Journal ID: ISSN 0163-1829; PRBMDO; TRN: US200907%%249
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Rev. B; Journal Volume: 75; Journal Issue: 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
03 NATURAL GAS; 08 HYDROGEN; ANISOTROPY; BONDING; CARBON; CARBON IONS; DEPOSITION; ELECTRON MICROSCOPES; ELECTRON MICROSCOPY; FLUCTUATIONS; FRICTION; HYDROGEN; HYDROGEN IONS; METHANE; SPECTROSCOPY; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Liu, A. C. Y., Arenal, R., Miller, D. J., Chen, X., Johnson, J. A., Eryilmaz, O. L., Erdemir, A., Woodford, J. B., and Cedarville Univ.. Structural order in near-frictionless diamond-like carbon films probed at three length scales in the transmission electron microscope.. United States: N. p., 2007. Web. doi:10.1103/PhysRevB.75.205402.
Liu, A. C. Y., Arenal, R., Miller, D. J., Chen, X., Johnson, J. A., Eryilmaz, O. L., Erdemir, A., Woodford, J. B., & Cedarville Univ.. Structural order in near-frictionless diamond-like carbon films probed at three length scales in the transmission electron microscope.. United States. doi:10.1103/PhysRevB.75.205402.
Liu, A. C. Y., Arenal, R., Miller, D. J., Chen, X., Johnson, J. A., Eryilmaz, O. L., Erdemir, A., Woodford, J. B., and Cedarville Univ.. Mon . "Structural order in near-frictionless diamond-like carbon films probed at three length scales in the transmission electron microscope.". United States. doi:10.1103/PhysRevB.75.205402.
@article{osti_948794,
title = {Structural order in near-frictionless diamond-like carbon films probed at three length scales in the transmission electron microscope.},
author = {Liu, A. C. Y. and Arenal, R. and Miller, D. J. and Chen, X. and Johnson, J. A. and Eryilmaz, O. L. and Erdemir, A. and Woodford, J. B. and Cedarville Univ.},
abstractNote = {A series of hydrogenated diamondlike carbon films grown using plasma-enhanced chemical-vapor deposition is systematically studied as a function of source gas composition using transmission electron microscopy. The structure of the films is examined at three distinct length scales. Both plan-view and cross-sectional studies are undertaken to reveal any large-scale inhomogeneities or anisotropy in the films. The degree of medium-range order in the films is measured by performing fluctuation electron microscopy on the plan-view and cross-sectional specimens. Electron-energy-loss spectroscopy is employed to measure the mass density and sp{sup 2}:sp{sup 3} carbon bonding ratios of the samples. Thus, inhomogeneity as a function of depth in the film is revealed by the measurements of the short- and medium-range orders in the two different sample geometries. Soft, low-density diamondlike carbon films with low coefficients of friction are found to be more homogeneous as a function of depth in the film and possess reduced medium-range order in the surface layer. We find that these properties are promoted by employing a high hydrogen content methane and hydrogen admixture as the growth ambient. In contrast, harder, denser films with higher coefficients of friction possess a distinct surface layer with a relatively elevated level of carbon sp{sup 3} bonding and a higher degree of medium-range order. The structure of the films is examined in the light of the energetics of the growth process. It appears that a high flux of penetrating hydrogen ions modifies the surface layer containing the remnant damage from the carbon ions, homogenizing it and contributing to a lowering of the coefficient of friction.},
doi = {10.1103/PhysRevB.75.205402},
journal = {Phys. Rev. B},
number = 2007,
volume = 75,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}