Thermal stability and nano-structure of metal-doped carbon layers

Journal of Nuclear Materials

De‐Juan‐Pardo

et al. 2007

Self Cite

The erosion by 30 and 200 eV/D at temperatures between 300 and 1100 K was investigated for magnetron-sputtered films, consisting of carbon and metal (2-7 at% W, Ti, Zr) present as nanometre-sized carbide crystallites. The total erosion yield was determined from weight-loss measurements and film thickness changes measured by RBS. The chemical erosion yield was obtained from the CD 4 signal of mass spectrometry. The total erosion yield of doped films is reduced by a factor of 3 to 20 compared to pure C films. The CD 4 production yield decreases less implying that the distribution of the chemically eroded species was changed by the dopants. Therefore, measuring only CD 4 production or its spectroscopic signature could yield to misleading values and interpretations.

Section: Discussionmentioning

confidence: 99%

Section: Film Production and Characterisationmentioning

confidence: 99%

Section: Film Production and Characterisationmentioning

confidence: 99%

“…The flux density was ~10set-up as well as to stabilize the chemical structure of the films, avoiding temperature-related changes during the erosion experiment [13,14].…”

Section: Erosion Experimentsmentioning

confidence: 99%

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Chemical erosion by deuterium impact on carbon films doped with nanometer-sized carbide crystallites

Journal of Nuclear Materials

De‐Juan‐Pardo

et al. 2007

Self Cite

“…They order on atomic scale by annealing (below 1000 K) [15,16]. Annealing at higher temperatures leads to growth of nano-crystallites detectable with XRD by width changes of the diffraction peaks [14,26], e.g., at ~1100 K for 0.25 h, 6, 3, and ~2 nm large carbide grains are formed in 8.5 at% V, 7 at% Zr, and 6 at% Ti-doped films, respectively. For lower concentrations of these dopants, the diffracted intensity is too low and too strongly widened to be separated from the background.…”

Section: Tih 38mentioning

confidence: 99%

Characterization and erosion of metal-containing carbon films

2007

Phys. Scr.

The annealing of magnetron-sputtered carbon films doped with up to 8.5 at% W, Ti, V, and Zr prior the erosion experiments led to formation of carbide cyrstallites of several nm. Ti, V, and Zr always reduces the total erosion yield by a factor of up to 20 compared to a pure C film. A temperature dependency of the metal erosion was observed. The methane production yield was studied by mass spectrometry. The CD 4 production yield decreases less than the total yield or even increases. This implies that the distribution of the chemically eroded species is changed by the dopants. It can be speculated that the re-deposition of carbon is reduced by doping.

Erosion Behaviour of Metal‐Doped Carbon Layers in Deuterium Low Pressure Plasmas and the Determination by Optical Emission Spectroscopy

Starke

2007

Contrib. Plasma Phys.

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The erosion behaviour of doped carbon materials was investigated in deuterium low pressure discharges. Therefore, amorphous carbon films on silicon substrates (film thickness ∼1 µm) with varying dopant species (V, Ti and W), dopant concentration (between 1 at% and 8.5 at%) and dopant distribution were exposed to the plasma. The dopant distribution is either atomically disperse or, by heating up to 1100 K, carbide grains in nm size are formed. All important plasma parameters are obtained by a combination of several diagnostic techniques like optical emission spectroscopy, energy resolved mass spectroscopy and Langmuir probe measurements. The morphology of the plasma treated surfaces was investigated afterwards by scanning electron microscopy and atomic force microscopy, the layer composition by ion beam analysis. Every investigated sample shows a strong decrease of the erosion yield with increasing fluence. The achieved erosion yields are clearly below the yield of undoped amorphous carbon and depend strongly on the dopant concentration. The lowest yields were achieved with the samples with atomically disperse dopant distribution due to metal enrichment at the surface.