Sponge-like carbon thin films: The dealloying concept applied to copper/carbon nanocomposite

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Ionized Physical Vapour Deposition combined with PECVD, for synthesis of carbon–metal nanocomposite thin films

International audienceCarbon–metal composite thin films were synthesized by a hybrid process combining magnetron sputtering and PECVD in an argon–methane plasma. Titanium was chosen as the target metal. The paper is focused on the impact of three types of deposition process (DC magnetron, RF magnetron or Ionized Physical Vapour Deposition – IPVD) on thin films' deposition and microstructure. The effect of the methane fraction in gas discharge was also studied. Films were analysed by EDX, XPS and XRD. Results indicate steady deposition conditions for RF or IPVD operation whatever the methane fraction in the discharge without any problem of discharge instability commonly observed in DC operation. The presence of TiC crystallites in a-C:H matrix was detected at intermediary methane fraction in discharge whatever the operating mode. Nevertheless, at constant methane fraction in discharge, strong difference between film microstructure and composition was observed according to the operating mode

Synthesis of nickel-filled carbon nanotubes at 350 degrees C

International audienceThe deposition of nickel/amorphous carbon (Ni/a-C) films by a hybrid plasma process combining magnetron sputtering of a Ni target and plasma enhanced chemical vapor deposition using methane gas has been investigated. The formation of nickel nanowires encapsulated by a-C matrix has been demonstrated by transmission electron microscopy (TEM). The obtained nanowires array can be easily dispersed or can be simply converted to a Ni-filled CNTarray by annealing at 350 C as confirmed by TEM analysis. The developed fabrication method of Ni-filled CNT array is a low temperature technique compatible with substrates of low melting point

X-ray reflectometry study of diamond-like carbon films prepared by plasma enhanced chemical vapor deposition in a low pressure inductively coupled plasma

International audienceIn this work we probe the structural properties of amorphous hydrogenated carbon thin films prepared by plasma-enhanced chemical vapor deposition in a low pressure inductively coupled plasma using X-ray reflectometry in order to study the effect of varying the ion energy on the density of these films. The ion energy is varied by varying the RF power used to bias the substrate. It is shown that a very low ion energy is already sufficient to obtain a dense diamond-like carbon (DLC) film, in contrast with other deposition techniques where much higher ion energies are required to obtain a dense DLC film. The results of this study are corroborated by Raman spectroscopy and ellipsometry measurements. The X-ray reflectometry data analysis is detailed in order to highlight some methodological problems encountered during the data fitting which could lead to an incorrect interpretation of the measured curves

EELS and NEXAFS structural investigations on the effects of the nitrogen incorporation in a-CNx films deposited by r.f. magnetron sputtering

This work presents the changes induced at the nanometer scale by the nitrogen incorporation into amorphous carbon nitride a-CNx films deposited by radio-frequency (r.f.) magnetron sputtering. High N content films (20 to 33 at.%) have been analysed by electron energy loss spectroscopy (EELS) and by near edge X-ray absorption fine structure (NEXAFS). EELS spectra at C K and N K edges roughly indicate the increase of the corresponding π* features, associated to N sp2 and C sp2 bonds, vs. the N content. Fine structures of the π* region of the N K edge spectra show at least three contributions, with different evolution depending on the N content. The discrepancies between the results recorded by these two techniques are only outward and they can be explained by the influence of the plasma parameters (pressure lying from 0.5 to 13 Pa and various Ar/N2 mixtures) on the deposition process. All the results are in good agreement with the XPS analysis of the N 1s data

Electrical behavior of nickel/carbon nanocomposite thin films

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Relation between residual stresses and microstructure in Mo(Cr) thin films elaborated by ionized magnetron sputtering

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Dealloying of gold-copper alloy nanowires: From hillocks to ring-shaped nanopores.

We report on a novel fabrication approach of metal nanowires with complex surface. Taking advantage of nodular growth triggered by the presence of surface defects created intentionally on the substrate as well as the high tilt angle between the magnetron source axis and the normal to the substrate, metal nanowires containing hillocks emerging out of the surface can be created. The approach is demonstrated for several metals and alloys including gold, copper, silver, gold-copper and gold-silver. We demonstrate that applying an electrochemical dealloying process to the gold-copper alloy nanowire arrays allows for transforming the hillocks into ring-like shaped nanopores. The resulting porous gold nanowires exhibit a very high roughness and high specific surface making of them a promising candidate for the development of SERS-based sensors

Dealloying of gold–copper alloy nanowires: From hillocks to ring-shaped nanopores

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Highly ordered ultralong magnetic nanowires wrapped in stacked graphene layers

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