Absolute densities of N and excited N2 in a N2 plasma

Agarwal, Sumit; Hoex, Bram; Sanden, M.C.M. van de; Maroudas, Dimitrios; Aydil, Eray S.

doi:10.1063/1.1630843

Cited by 71 publications

(46 citation statements)

References 20 publications

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“…These highly reactive species can affect the surface and thus deposition chemistry, especially the properties of the deposited thin film of GaN depend on the concentration of N and excited N 2 species during the film growth. (7) The main aim of this work is to obtain reliable information about the concentration of the active species (significant atoms, molecules and ions) of N 2 plasma, which determine the nitridation process in the plasma reactor and then to adjust optimum discharge conditions for the desired treatment of the samples in a simple and cost-effective manner.…”

Section: Introductionmentioning

confidence: 99%

Optical Emission Spectroscopy of Abnormal Glow Region in Nitrogen Plasma

Qayyum

Zeb

Ali

et al. 2005

Plasma Chem Plasma Process

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Optical emission spectroscopy of the active species in N 2 plasma is carried out to investigate their concentration as a function of discharge parameters such as filling pressure (2.0-7.0 mbar), source power (100-200 W) and gas flow rate (50-300 mg/min). The primary motivation of this work is to obtain reliable information about the concentration of the active species of N 2 plasma, which play an important role in plasma surface nitriding processes. Emission intensity from the selected electronic excited states of molecular and atomic species is evaluated as a function of discharge parameters to investigate their concentration. The emission intensity ratio I (N + 2 )/I (N 2 ) and I (N + )/I (N ) of the electronic transitions is also evaluated as a function of discharge parameters to investigate the relative dependence of their concentrations. It is observed that the concentration of the active species of N 2 plasma is strongly affected by the filling pressure and source power whereas flow rate has no significant effect. An increased occurrence of N + 2 molecular ions in comparison with N 2 molecules, and N + ions in comparison with N atoms is observed with source power whereas decreased occurrence of N + 2 molecular ions in comparison with N 2 molecules, and N + ions in comparison with N atoms is observed with the rise in filling pressure.

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Section: Introductionmentioning

confidence: 99%

Optical Emission Spectroscopy of Abnormal Glow Region in Nitrogen Plasma

Qayyum

Zeb

Ali

et al. 2005

Plasma Chem Plasma Process

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“…The radical wall loss time which is an important model input parameter is determined by monitoring the radical density in the temporal afterglow of the plasma with ionization threshold mass spectroscopy (ITMS) [47][48][49][50][51][52][53] . This technique takes advantage of the fact that the threshold energy for direct ionization of a radical, e.g., e − + N → N + + 2e − is lower than the threshold energy for the corresponding dissociative ionization of the mother molecules leading to the same ion, e.g., e − + N 2 → N + + N + 2e − .…”

Section: F Radical Wall Loss Timesmentioning

confidence: 99%

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

Sode

Jacob

Schwarz-Selinger

et al. 2015

Journal of Applied Physics

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A comprehensive experimental investigation of absolute ion and neutral species densities in an inductively coupled H 2 -N 2 -Ar plasma was carried out. Additionally, the radical and ion densities were calculated using a zero-dimensional rate equation model. The H 2 -N 2 -Ar plasma was studied at a pressure of 1.5 Pa and an rf power of 200 W. The N 2 partial pressure fraction was varied between f N 2 = 0 % and 56 % by a simultaneous reduction of the H 2 partial pressure fraction. The Ar partial pressure fraction was held constant at about 1 %. NH 3 was found to be produced almost exclusively on the surfaces of the chamber wall. NH 3 contributes up to 12 % to the background gas.To calculate the radical densities with the rate equation model it is necessary to know the corresponding wall loss times t wrad of the radicals. t wrad was determined by the temporal decay of radical densities in the afterglow with ionization threshold mass spectrometry during pulsed operation and based on these experimental data the absolute densities of the radical species were calculated and compared to measurement results.Ion densities were determined using a plasma monitor (mass and energy resolved mass spectrometer). H + 3 is the dominant ion in the range of 0.0 ≤ f N 2 < 3.4 %. For 3.4 < f N 2 < 40 % NH + 3 and NH + 4 are the most abundant ions and agree with each other within the experimental uncertainty. For f N 2 = 56 % N 2 H + is the dominant ion while NH + 3 and NH + 4 have only a slightly lower density. Ion species with densities in the range between 0.5 and 10 % of n i,tot are H + 2 , ArH + , and NH + 2 . Ion species with densities less than 0.5 % of n i,tot are H + , Ar + , N + , and NH + . Our model describes the measured ion densities of the H 2 -N 2 -Ar plasma reasonably well. The ion chemistry, i.e., the production and loss processes of the ions and radicals, are discussed in detail. The main features, i.e., the qualitative abundance of the ion species and the ion density dependence on the N 2 partial pressure fraction, are well reproduced by the model.

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“…[1][2][3][4] It is capable of detection of a variety of lowdensity reactive gas phase species at a substrate position without the limitations, inherent to some of the optical techniques, such as the existence of suitable optical transitions of the radical or the molecule of interest. TIMS has been successfully applied for the radical density measurements, for example, in SiH 4 -CH 4 -H 2 glow discharge plasma, 2 Cl 2 plasma used for Si etching, 5 O 2 and N 2 plasmas, 1, 6 and hot filament diamond chemical vapor deposition ͑CVD͒.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Agarwal et al reported TIMS measurement of absolute densities of electronically excited N 2 in an inductively coupled N 2 plasma. 6 Although TIMS is a versatile technique, it requires a carefully designed differentially-pumped housing for the quadrupole mass spectrometer ͑QMS͒ and a proper calibration procedure to accurately determine the absolute number density of the radicals. Knowledge of the absolute density of various reactive species in a plasma is essential for the validation of plasma chemistry models, since their results are often dependent on unknown reaction rates and reaction branching ratios.…”

Section: Introductionmentioning

confidence: 99%

Threshold ionization mass spectrometry of reactive species in remote Ar∕C2H2 expanding thermal plasma

Benedikt

Agarwal

Eijkman

et al. 2005

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's 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 ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Triple stage threshold ionization mass spectrometry is successfully implemented in an Ar/ C 2 H 2 expanding thermal plasma setup. More than 20 hydrocarbon radicals and molecules formed in the plasma, including for example the C 2 H, C 3 , C 3 H, and C 3 H 2 radicals or C 3 H 4 or C 4 H 2 molecules, are measured and their absolute densities are determined. Thanks to a careful design, a high sensitivity of the instrument is achieved and species with densities as low as 1 ϫ 10 16 m −3 can be detected. Issues related to the absolute density calibration procedure are considered. The proper determination of the background signal by means of a beam chopper and the influence of the chopper on the measurement are discussed and the possible composition distortion of the sampled beam due to the collisions in the sampling orifice is checked. Furthermore, reported values of electron impact ionization cross sections of hydrocarbon species are compared and, based on their similarity in the near threshold energy region, the C 2 H 2 electron impact ionization cross section is proposed as a reasonable approximation for other hydrocarbon radicals. The results for C, CH, and C 2 radicals are compared with previous cavity ringdown absorption spectroscopy measurements and a good agreement is obtained.

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Absolute densities of N and excited N2 in a N2 plasma

Abstract: Agarwal, S.; Hoex, B.; van de Sanden, M.C.M.; Maroudas, D.; Aydil, E.S.

Cited by 71 publications

References 20 publications

Optical Emission Spectroscopy of Abnormal Glow Region in Nitrogen Plasma

Optical Emission Spectroscopy of Abnormal Glow Region in Nitrogen Plasma

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

Threshold ionization mass spectrometry of reactive species in remote Ar∕C2H2 expanding thermal plasma

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