Filament poisoning at typical carbon nanotube deposition conditions by hot-filament CVD

Oliphant, Clive J.; Arendse, Christopher J.; Malgas, Gerald F.; Motaung, David E.; Muller, T.F.G.; Halindintwali, S.; Julies, B.; Knoesen, D.

doi:10.1007/s10853-009-3341-y

Cited by 11 publications

(11 citation statements)

References 23 publications

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“…The observation of crystalline W 2 C is similar to our recent study using TMDSCB 12,20 and other studies. [10][11][12]19 For the W filaments exposed to DSCB for longer time of 3 hr and beyond, weak XRD peaks due to W 5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 the parabolic law where the thickness is linearly proportional to the square root of time. This suggests that the growth is diffusion controlled.…”

Section: Resultsmentioning

confidence: 99%

“…The catalytic dissociation reactions are key to the success of the actual deposition since they initiate the gas-phase reaction chemistry and thin film growth. However, the heterogeneous reactions between the gaseous reactive species and the heated metal wire itself also result in the formation of metal alloys, such as metal silicides − and metal carbides, − on the wire surface. Several studies showed that the filament alloying affects the catalytic ability of the metal wire , as well as the quality of the deposited thin films. , A more detrimental effect from the filament alloying is the shortening of its lifetime.…”

Section: Introductionmentioning

confidence: 99%

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Structural Changes in Tungsten and Tantalum Wires in Catalytic Chemical Vapor Deposition Using 1,3-Disilacyclobutane

2015

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Metal wires (typically made of W or Ta) serve as catalysts to decompose the precursor gases to form reactive species in the technique of catalytic chemical vapor deposition. The reactions of these reactive species with the heated wire cause structure changes in the wire, which affects its catalytic properties and lifetime. Here, we report a systematic study on characterizing the structural changes in W and Ta wires when they are exposed to 1,3-disilacylobutane, a useful single-source precursor for SiC film deposition. We have shown that filament temperature, reaction time, and filament material are among the important factors in determining the nature of metal alloys formed. Formation of crystalline W 2 C, SiC, and W 5 Si 3 (weak) was observed on W, whereas crystalline TaC, SiC, and Ta 5 Si 3 (weak) were formed on Ta. While both filaments proved to form cubic crystalline 3C-SiC at low temperatures, alloying has taken different paths at higher temperatures. Between 1400 -2400 °C, alloying in W was dominated by the formation of W 2 C with little contribution from WC. For Ta, the main alloy formed was TaC in the temperature range of 1400 -2000 °C. Heating the aged Ta filament to temperatures higher than 2000 ºC tended to recover the metal wire. This same practice does not seem to work for W wires since more W 2 C are formed at high temperatures. It is concluded that Ta outperforms W for SiC film growth in its resistance to forming more carbides and its ability to recover at high temperatures.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural Changes in Tungsten and Tantalum Wires in Catalytic Chemical Vapor Deposition Using 1,3-Disilacyclobutane

2015

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“…W, one of the most widely used wire materials, can easily be carburized when exposed to organic material gases [1][2][3][4][5]. Silicidation is a problem when we use SiH 4 or organosilicon compounds, although the silicidation by SiH 4 is rather minor at high temperatures, i.e., over 1.810 3 K [3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Hot metal wires as sinks and sources of B atoms

Umemoto

Miyata

2017

Thin Solid Films

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Metal wires, such as W, Mo, and Ta, can be boronized to become sinks of B atoms by heating them in the presence of a mixture of H 2 and H 3 NBH 3 or (BH) 3 (NH) 3. These boronized wires behave as sources of B atoms when heated in vacuum. The density of B atoms released to the gas phase increases with the addition of H 2 and can be more than 10 11 cm-3 , which is enough for surface doping. The release is stable and continues for more than several hours when boronized for 1 h. Since the metal wires are not nitrided, contamination by N atoms is not expected. H 3 NBH 3 and (BH) 3 (NH) 3 are not explosive, and wires boronized by these species can be used as safe and contamination-free sources of B atoms for surface doping.

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“…Versatility of the hot-wire chemical vapor deposition (HWCVD) technique is reflected in its application to synthesize a diverse range of materials such as hydrogenated silicon thin films (Mahan et al, 1991), diamond films (Moustakas, 1989), carbon microcoils (Chen et al, 2008; Oliphant et al, 2009 a ), polymer films (Pryce Lewis et al, 2009), and carbon nanotubes (CNTs) (Dillon et al, 2003). During the HWCVD process, the precursors are dissociated by a resistively heated filament resulting in reactive species that can react with each other en route to a substrate where eventual material deposition occurs.…”

Section: Introductionmentioning

confidence: 99%

EBSD Analysis of Tungsten-Filament Carburization During the Hot-Wire CVD of Multi-Walled Carbon Nanotubes

et al. 2014

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Filament condition during hot-wire chemical vapor deposition conditions of multi-walled carbon nanotubes is a major concern for a stable deposition process. We report on the novel application of electron backscatter diffraction to characterize the carburization of tungsten filaments. During the synthesis, the W-filaments transform to W2C and WC. W-carbide growth followed a parabolic behavior corresponding to the diffusion of C as the rate-determining step. The grain size of W, W2C, and WC increases with longer exposure time and increasing filament temperature. The grain size of the recrystallizing W-core and W2C phase grows from the perimeter inwardly and this phenomenon is enhanced at filament temperatures in excess of 1,400°C. Cracks appear at filament temperatures >1,600°C, accompanied by a reduction in the filament operational lifetime. The increase of the W2C and recrystallized W-core grain size from the perimeter inwardly is ascribed to a thermal gradient within the filament, which in turn influences the hardness measurements and crack formation.

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Filament poisoning at typical carbon nanotube deposition conditions by hot-filament CVD

Cited by 11 publications

References 23 publications

Structural Changes in Tungsten and Tantalum Wires in Catalytic Chemical Vapor Deposition Using 1,3-Disilacyclobutane

Structural Changes in Tungsten and Tantalum Wires in Catalytic Chemical Vapor Deposition Using 1,3-Disilacyclobutane

Hot metal wires as sinks and sources of B atoms

EBSD Analysis of Tungsten-Filament Carburization During the Hot-Wire CVD of Multi-Walled Carbon Nanotubes

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