Argon-hydrogen plasma jet investigated by active and passive spectroscopic means

Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement: A combination of experiment ͓optical emission and cavity ring-down spectroscopy ͑CRDS͒ of electronically excited H atoms͔ and two-dimensional ͑2D͒ modeling has enabled a uniquely detailed characterization of the key properties of the Ar/ H 2 plasma within a ഛ10-kW, twin-nozzle dc arc jet reactor. The modeling provides a detailed description of the initial conditions in the primary torch head and of the subsequent expansion of the plasma into the lower pressure reactor chamber, where it forms a cylindrical plume of activated gas comprising mainly of Ar, Ar + , H, ArH + , and free electrons. Subsequent reactions lead to the formation of H 2 and electronically excited atoms, including H͑n =2͒ and H͑n =3͒ that radiate photons, giving the plume its characteristic intense emission. The modeling successfully reproduces the measured spatial distributions of H͑n Ͼ 1͒ atoms, and their variation with H 2 flow rate, F H 2 0 . Computed H͑n =2͒ number densities show near-quantitative agreement with CRDS measurements of H͑n =2͒ absorption via the Balmer-␤ transition, successfully capturing the observed decrease in H͑n =2͒ density with increased F H 2 0 . Stark broadening of the Balmer-␤ transition depends upon the local electron density in close proximity to the H͑n =2͒ atoms. The modeling reveals that, at low F H 2 0 , the maxima in the electron and H͑n =2͒ atom distributions occur in different spatial regions of the plume; direct analysis of the Stark broadening of the Balmer-␤ line would thus lead to an underestimate of the peak electron density. The present study highlights the necessity of careful interco...

Section: Introductionmentioning

confidence: 99%

Measurement and modeling of a diamond deposition reactor: Hydrogen atom and electron number densities in an Ar∕H2 arc jet discharge

Rennick

Engeln

Smith

et al. 2005

“…As discussed in our previous papers this is due to efficient wall association of atomic hydrogen and a less efficient arc operation at high hydrogen admixture. 21,22,[24][25][26] In Fig. 3 the silane depletion ͑ϭrelative consumption͒ D as calculated for the various mass peaks of the cracking pattern of silane is shown as a function of the hydrogen flow admixed in the arc.…”

Section: Resultsmentioning

confidence: 99%

“…For example, for a pure argon plasma the fluence of argon ions can be determined from electron and ion density measurements by means of Thomson-Rayleigh scattering and Langmuir probe. [20][21][22][23][24][25][26] This fluence of ions and electrons than interacts with, e.g., silane or hydrogen injected in the chamber. The silane injected is dissociated and deposits on the wall.…”

Section: Resultsmentioning

confidence: 99%

“…The influence of hydrogen dilution of the argon carrier gas will be interpreted in view of previously published results obtained by Thomson-Rayleigh scattering and Langmuir probe measurements and related to the depletion of silane downstream. [20][21][22][23][24][25][26] The results will be compared to the results obtained using other types of remote plasmas and conventional plasma enhanced chemical vapor deposition ͑PECVD͒ of a-Si:H.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Plasma chemistry aspects of a-Si:H deposition using an expanding thermal plasma

Sanden

Severens

Kessels

et al. 1998

Self Cite

118

The plasma chemistry of an argon/hydrogen expanding thermal arc plasma in interaction with silane injected downstream is analyzed using mass spectrometry. The dissociation mechanism and the consumption of silane are related to the ion and atomic hydrogen fluence emanating from the arc source. It is argued that as a function of hydrogen admixture in the arc, which has a profound decreasing effect on the ion-electron fluence emanating from the arc source, the dissociation mechanism of silane shifts from ion-electron induced dissociation towards atomic hydrogen induced dissociation. The latter case, the hydrogen abstraction of silane, leads to a dominance of the silyl (SiH 3 ) radical whereas the ion-electron induced dissociation mechanism leads to SiH x (xϽ3) radicals. In the pure argon case, the consumption of silane is high and approximately two silane molecules are consumed per argon ion-electron pair. It is shown that this is caused by consecutive reactions of radicals SiH x (xϽ3) with silane. Almost independent of the plasma conditions used, approximately one H 2 is produced per consumed SiH 4 molecule. Disilane production is observed which roughly scales with the remaining silane density. Possible production mechanisms for both observations are discussed.

“…With less than 2%-3% of H 2 (D 2 ), the ion composition consists of Ar þ , ArH þ (ArD þ ), and H þ 3 (D þ 3 ). [72][73][74] In gas mixtures with a higher H 2 content, that role is again fulfilled by H þ 3 . 75 The cascaded arc and plasma expansion itself have been characterized in more detail elsewhere, e.g.…”

Section: A Expanding Thermal Plasmamentioning

confidence: 99%

Synergistic etch rates during low-energetic plasma etching of hydrogenated amorphous carbon

Hansen

Weber

Colsters

et al. 2012

Self Cite

The etch mechanisms of hydrogenated amorphous carbon thin films in low-energetic (<2 eV) high flux plasmas are investigated with spectroscopic ellipsometry. The results indicate a synergistic effect for the etch rate between argon ions and atomic hydrogen, even at these extremely low kinetic energies. Ion-assisted chemical sputtering is the primary etch mechanism in both Ar/H2 and pure H2 plasmas, although a contribution of swift chemical sputtering to the total etch rate is not excluded. Furthermore, ions determine to a large extent the surface morphology during plasma etching. A high influx of ions enhances the etch rate and limits the surface roughness, whereas a low ion flux promotes graphitization and leads to a large surface roughness (up to 60 nm).