Dissociation kinetics of molecular hydrogen in a microwave plasma and its influence on the hydrogen content in diamond films

Sharda, T.; Misra, D.; Avasthi, D.K.; Mehta, Goverdhan

doi:10.1016/0038-1098(96)00040-3

Cited by 39 publications

(19 citation statements)

References 17 publications

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“…In an earlier study,17 characteristics of the plasma formed in our microwave plasma chemical vapor deposition (MPCVD) system had been investigated. At a pressure of 70 Torr (1 Torr = 133.322 Pa) and a temperature of 925 °C the mixture of hydrogen and methane gases (with 99.2% H 2 ) yielded the following temperature and density of electrons: T eV ≈ 10 eV and n ≈ 10 18 m −3 .…”

Section: Introductionmentioning

confidence: 99%

Enhanced Field Emission and Improved Supercapacitor Obtained from Plasma‐Modified Bucky Paper

Roy

Bajpai

Soin

et al. 2011

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The surface morphology of bucky papers (BPs) made from single-walled carbon nanotubes (CNTs) is modified by plasma treatment resulting in the formation of vertical microstructures on the surface. The shapes of these structures are either pillarlike or conelike depending on whether the gas used during plasma treatment is Ar or CH(4) . A complex interplay between different factors, such as the electric field within the plasma sheath, polarization of the CNT, intertubular cohesive forces, and ion bombardment, result in the formation of these structures. The roles played by these factors are quantitatively and qualitatively analyzed. The final material is flexible, substrate-free, composite-free, made only of CNTs, and has discrete vertically aligned structures on its surface. It shows enhanced field emission and electrochemical charge-storage capabilities. The field enhancement factor is increased by 6.8 times, and the turn-on field drops by 3.5 times from an initial value of 0.35 to 0.1 V μm(-1) as a result of the treatment. The increase in Brunauer-Emmett-Teller surface area results in about a fourfold improvement in the specific capacitance of the BP electrodes. Capacitance values before and after the treatments are 75 and 290 F g(-1) , respectively. It is predicted that this controlled surface modification technique could be put to good use in several applications based on macroscopic CNT films.

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Section: Introductionmentioning

confidence: 99%

Enhanced Field Emission and Improved Supercapacitor Obtained from Plasma‐Modified Bucky Paper

Roy

Bajpai

Soin

et al. 2011

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“…The lifetime of hydrogen active groups is much longer than CH3 active group, and the CH3 active group is sensitive to the chamber pressure [33] . Second, the concentration of hydrogen atoms was reduced with reduced pressure [34] . Therefore, the ratio of CH3 groups to H groups on substrate increases with the decreased chamber pressure.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of strong SiV photoluminescent diamond particles on silica optical fiber by chemical vapor deposition

Zheng¹,

Mei²,

Chen³

et al. 2018

Chinese Phys. B

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The separated silicon-vacancy (SiV) photoluminescent diamond particles were synthesized on silica optical fiber by hot filament chemical vapor deposition (HFCVD). The effects of pre-treated method and chamber pressure on the microstructure and photoluminescence of diamond particles are investigated. The results show that diamond particles are homogeneously distributed on the surface of optical fiber, which is dip-coated into the slurry consisting of nanodiamond particles for 2-5 minutes. With chamber pressure increasing from 1.6 to 3.5 kPa, the shape of particles transits from flake to circle, while diamond particles cannot be deposited on the fiber with pressure further increasing to 4.5 kPa. The samples synthesized under 2.5 kPa chamber pressure are composed of diamond particles with size around 200-400 nm, exhibiting stronger SiV photoluminescence with the width of around 6 nm.

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“…It has been shown previously that the dissociation rate of molecular hydrogen increases with the increase in the MPD. 6 This is inspite of the increased recombination at higher pressure because of the considerable reduction in the size of the plasma ball. In agreement with Loh and Capelli, 29 we also observe that as the size of the plume decreases the temperature of the plasma ͑plasma ball͒ as well as the atomic H content increases.…”

Section: Discussionmentioning

confidence: 99%

“…Microwave plasma chemical vapor deposition ͑MPCVD͒ is one of the techniques that has been used extensively to grow the films. 1,5 The high density and energy of the electrons in a microwave plasma dissociate H 2 molecules to provide the high concentration of atomic hydrogen ͑H͒, 6 which not only preferentially etches sp 2 carbon but also enhances the density of sp 3 carbon species. 7 However, owing to the nature of the plasma processes, various growth parameters such as T s , growth pressure, and microwave power become dependent upon each other making it difficult to identify the parameters affecting the growth significantly.…”

Section: Introductionmentioning

confidence: 99%

Stoichiometry of the diamond/silicon interface and its influence on the silicon content of diamond films

Sharda

Vaidya

Misra

et al. 1998

Journal of Applied Physics

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Atomically flat interface between a single-terminated LaAlO3 substrate and SrTiO3 thin film is insulating AIP Advances 2, 012147 (2012) Interfaces between nonpolar and semipolar III-nitride semiconductor orientations: Structure and defects J. Appl. Phys. 111, 033507 (2012) Direct patterning of functional interfaces in oxide heterostructures Appl. Phys. Lett. 100, 041601 (2012) Evolution of nanoscale roughness in Cu/SiO2 and Cu/Ta interfaces Appl. Phys. Lett. 100, 024106 (2012) Additional information on J. Appl. Phys. Thin films of diamond were grown by microwave plasma chemical vapor deposition at growth pressures of 10, 20, 40, and 60 Torr keeping the substrate temperature constant at 975°C. Increase in the growth pressure reduced the size of the plasma ball resulting in an increase in the microwave power density ͑MPD͒. The films were characterized by scanning electron microscopy, micro-Raman, and photoluminescence ͑PL͒ spectroscopy. A systematic variation was observed in surface morphology and quality of the films. The intensity of the peak at 1.68 eV in the PL spectra of the films, which is assigned to Si impurities was also observed to increase consistently with the MPD. The stoichiometry of the diamond/silicon interface was studied by x-ray photoelectron spectroscopy ͑XPS͒ and found to be a sensitive function of the MPD. XPS results showed the formation of nonstoichiometric SiC along with other carbon phases in the initial stages of the growth. A correlation was observed between the composition of the interface and the intensity of the 1.68 eV peak. The above results are explained in terms of the increase in the impingement flux density of atomic hydrogen with the MPD.

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Dissociation kinetics of molecular hydrogen in a microwave plasma and its influence on the hydrogen content in diamond films

Cited by 39 publications

References 17 publications

Enhanced Field Emission and Improved Supercapacitor Obtained from Plasma‐Modified Bucky Paper

Enhanced Field Emission and Improved Supercapacitor Obtained from Plasma‐Modified Bucky Paper

Synthesis of strong SiV photoluminescent diamond particles on silica optical fiber by chemical vapor deposition

Stoichiometry of the diamond/silicon interface and its influence on the silicon content of diamond films

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