Structure and spectroscopic properties of C-Ni and CN{sub x}-Ni nanocomposite films

Journal Article · Mon Aug 01 00:00:00 EDT 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2001746· OSTI ID:20714030

Kovacs, Gy J; Koos, A; Bertoni, G; Safran, G; Geszti, O; Serin, V; Colliex, C; Radnoczi, G ^[1]

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1. Research Institute for Technical Physics and Materials Science, H-1525 Budapest, P.O. Box 49 (Hungary)

Magnetron-sputtered carbon-nickel and carbon-nitride-nickel thin films were investigated by high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy, electron-energy-loss spectroscopy (EELS), and scanning tunneling microscopy/spectroscopy (STM/STS) to clarify the relationship between the structure and the spectroscopic properties. The films were deposited in argon or nitrogen plasma at temperatures from 25 to 800 deg. C. The microstructures can be described as a nanocomposite, built from Ni or Ni{sub 3}C nanocrystals in a carbon/CN{sub x} matrix. The nanocomposite shows columnar structure up to 200 deg. C deposition temperature, and above this temperature gradually changes to globular morphology. The C/CN{sub x} matrix also grows thicker as the deposition temperature increases. The matrix is amorphous at high nitrogen content and low deposition temperature and it is ordered into 3-5 layer thick graphitic shells around the Ni{sub 3}C or Ni crystallites at higher temperatures. The surface roughness of the nanocomposite ranges between 0.7 and 2.3 nm, increasing with increasing deposition temperature. EELS measurements confirm the expected chemical interaction between nickel and carbon. EELS suggests that the nitrogen is incorporated only into the matrix in CN{sub x}-Ni samples, mainly with sp{sup 1} bonds for deposition temperature below 500 deg. C. STS investigations show that the conductivity increases with increasing deposition temperature. A conductivity gap of 1-2 V exists in the nanocomposite films. A structural model based on the HRTEM investigation is given that can describe the spectroscopic properties and their behavior with the deposition temperature.

• OSTI ID: 20714030
• Journal Information: Journal of Applied Physics, Vol. 98, Issue 3; Other Information: DOI: 10.1063/1.2001746; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
ARGON
CARBON
CARBON NITRIDES
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ENERGY-LOSS SPECTROSCOPY
MICROSTRUCTURE
MORPHOLOGY
NANOSTRUCTURES
NICKEL
NITROGEN
PLASMA
ROUGHNESS
SCANNING TUNNELING MICROSCOPY
SPUTTERING
STRUCTURAL MODELS
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY SPECTROSCOPY