Thermal stability of amorphous hard carbon films produced by cathodic arc deposition

Anders, S.; Dı́az, J.; Ager, Joel W.; Lo, Roger Yu; Bogy, David B.

doi:10.1063/1.120339

Cited by 102 publications

(43 citation statements)

References 26 publications

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“…S1). Since TEY detected NEXAFS is a surface sensitive technique with electron escape depth~5 nm [43], this result indicates no change to surface composition. The increased intensity at 300 eV is likely due to the subtle structural rearrangement of SeP3MEET with more side-chains at the film/air interface after annealing.…”

Section: Molecular Doping Of the Polar Layermentioning

confidence: 88%

The effect of thermal annealing on dopant site choice in conjugated polymers

Rochester

Jacobs

et al. 2016

Organic Electronics

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a b s t r a c tSolution-processed organic electronic devices often consist of layers of polar and non-polar polymers. In addition, either of these layers could be doped with small molecular dopants. It is extremely important for device stability to understand the diffusion behavior of these molecular dopants under the thermal stress and whether the dopants have preference for the polar or the non-polar polymer layers. In this work, a widely used molecular dopant 2, 3,5,7,8, was chosen to investigate dopant site preference upon thermal annealing between the polar thiophene poly(thiophene-3-[2-(2-methoxy-ethoxy)ethoxy]-2,5-diyl) (SeP3MEET) and non-polar thiophene poly(3-hexylthiophene) (P3HT). F4TCNQ is able to p-type dope both P3HT and SeP3MEET. Further doping studies of SeP3MEET using near edge X-ray absorption fine structure spectroscopy, conductivity measurements and atomic force microscopy show that the F4TCNQ additive competes for doping sites with the covalently attached dopants on the SeP3MEET. Calorimetry measurements reveal that the F4TCNQ interacts strongly with the side-chains of the SeP3MEET, increasing the melting temperature of the side-chains by 30 C with 5 wt% dopant loading. Next, the thermal stability of doping in the polar/ non-polar (SeP3MEET/P3HT) bilayer architectures was investigated. Steady-state absorbance and fluorescence results show that F4TCNQ binds much more strongly in SeP3MEET than P3HT and very little F4TCNQ is found in the P3HT layer after annealing. In combination with reflectometry measurements, we show that F4TCNQ remains in the SP3MEET layer with annealing to 210 C even though the sublimation temperature for neat F4TCNQ is about 80 C. In contrast, F4TCNQ slowly diffuses out of P3HT at room temperature. We attribute this difference in binding the F4TCNQ anion to the ability of the ethyl-oxy side-chains of the SeP3MEET to orient around the charged dopant molecule and thereby to stabilize its position. This study suggests that polar side-chains could be engineered to increase the thermal stability of molecular dopant position.

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Section: Molecular Doping Of the Polar Layermentioning

confidence: 88%

The effect of thermal annealing on dopant site choice in conjugated polymers

Rochester

Jacobs

et al. 2016

Organic Electronics

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“…The C 1s → ‫ء‬ peak in the graphite spectrum is located at 285.5 eV, which is the proper location for ordered sp 2 bonding, and the C 1s → ‫ء‬ transition begins at a higher energy ͑Ͼ290 eV͒ which is a known characteristic of ordered sp 2 -bonded carbon. The NEXAFS TEY spectrum of as-deposited ta-C exhibits a peak at 285.0 eV due to the C 1s → ‫ء‬ transition for disordered carboncarbon sp 2 -hybridized bonds, 21 and a broad hump starting above 288 eV and extending up to 305 eV due to the C 1s → ‫ء‬ transition for disordered carbon-carbon bonds. These are all typical features of amorphous carbon films.…”

Section: Resultsmentioning

confidence: 99%

“…Alam et al 12 used nuclear magnetic resonance ͑NMR͒ spectroscopy to reveal than the sp 3 content of an initially 82% sp 3 -bonded ta-C film ͑grown using the same method and growth system in this work͒ changed by Ͻ2% when heated to 650°C for annealing times up to 4 min. Raman and near-edge x-ray absorption fine structure ͑NEXAFS͒ spectroscopies were employed by Anders et al 21 on ta-C films deposited by cathodic arc and annealed up to 850°C for 15 min, and they found that while Raman showed only subtle spectral changes, NEXAFS revealed significant increases in the sp 2 character for films annealed above 700°C. Orwa et al used transmission electron microscopy ͑TEM͒ combined with EELS and Raman spectroscopy to determine if the sp 2 bonds ta-C ͑filtered cathodic arc grown͒ tend to cluster at higher annealing temperatures ͑up to 1100°C͒.…”

Section: Introductionmentioning

confidence: 99%

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Thermal stability and rehybridization of carbon bonding in tetrahedral amorphous carbon

Grierson¹,

Sumant²,

Konicek

et al. 2010

Journal of Applied Physics

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We preform a quantitative investigation of the energetics of thermally induced sp 3 → sp 2 conversion of carboncarbon bonds in tetrahedral amorphous carbon (ta-C) films by using near edge x-ray absorption fine structure (NEXAFS) and Raman spectroscopy. We investigate the evolution of the bonding configuration in ta-C thin films subjected to high temperature annealing in flowing Argon gas using a rapid thermal annealing furnace over the range of 200-1000 ºC. We observe no substantial change in bonding structure below 600 ºC, and by 1000 ºC a significant increase in the sp 2 bonding in the film is observed. No oxygen bonding is detected in the NEXAFS spectra, but we do observe an isosbestic point, demonstrating that the thermally driven sp 3 → sp 2 conversion reaction occurs without passing through an intermediate transition state. This allows us to use NEAFS spectra of thermally annealed ta-C films to quantitatively determine that the activation energy for directly converting the sp 3 -bonded carbon to the sp We perform a quantitative investigation of the energetics of thermally induced sp 3 → sp 2 conversion of carbon-carbon bonds in tetrahedral amorphous carbon ͑ta-C͒ films by using near-edge x-ray absorption fine structure ͑NEXAFS͒ and Raman spectroscopy. We investigate the evolution of the bonding configuration in ta-C thin films subjected to high temperature annealing in flowing Argon gas using a rapid thermal annealing furnace over the range of 200-1000°C. We observe no substantial change in bonding structure below 600°C. Changes in the NEXAFS and Raman spectra start to appear above 600°C, and by 1000°C a significant increase in the sp 2 bonding in the film is observed. No oxygen bonding is detected in the NEXAFS spectra, but we do observe an isosbestic point, demonstrating that the thermally driven sp 3 → sp 2 conversion reaction occurs without passing through an intermediate transition state. This allows us to use NEXAFS spectra of thermally annealed ta-C films to quantitatively determine that the activation energy for directly converting the sp 3 -bonded carbon to the sp 2 -bonded configuration is 3.5Ϯ 0.9 eV.

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“…Traditionally DLC has been prepared by Pulsed Laser Deposition (PLD) [4], Filtered Cathodic Arc (FCA) [5,6] and Mass Selected Ion Beam (MSIB) [7]. DLC is currently used as overcoats in magnetic disks and heads, as an ultra thin layer (less than 10 nm), for protection of the magnetic media against wear and environmental degradation.…”

Section: Introductionmentioning

confidence: 99%

Engineering Properties of Superhard Films with Ion Energy and Post-Deposition Processing

Monteiro

Delplancke‐Ogletree²

2003

AIP Conference Proceedings

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Abstract. Recent developments in plasma synthesis of hard materials using energetic ions are described. Metal Plasma Immersion Ion Implantation and Deposition (MePIIID) has been used to prepare several hard films: from diamondlike carbon (DLC) to carbides, from nitrides to oxides. The energy of the depositing species is controlled to maximize adhesion as well as to change the physical and chemical properties of the films. Adhesion is promoted by the creation of a graded interface between the film and the substrate. The energy of the depositing ions is also used to modify and control the intrinsic stresses and the microstructure of the films. The deposition is carried out at room temperature, which is important for temperature sensitive substrates. A correlation between intrinsic stresses and the energetics of the deposition is presented for the case of DLC films, and means to reduce stress levels are discussed.

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Thermal stability of amorphous hard carbon films produced by cathodic arc deposition

Abstract: The thermal stability of amorphous hard carbon films produced by cathodic arc deposition was studied by Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, Raman spectroscopy. and nanoindentation evaluation. Pure carbon films of

Cited by 102 publications

References 26 publications

The effect of thermal annealing on dopant site choice in conjugated polymers

The effect of thermal annealing on dopant site choice in conjugated polymers

Thermal stability and rehybridization of carbon bonding in tetrahedral amorphous carbon

Engineering Properties of Superhard Films with Ion Energy and Post-Deposition Processing

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