On the ionic chemistry in DC cold plasmas of H2 with Ar

Méndez, Isabel; Tanarro, Isabel; Herrero, Vı́ctor J.

doi:10.1039/b925202a

Cited by 18 publications

(32 citation statements)

References 49 publications

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“…Ion densities were calculated but only compared to uncalibrated signal intensities of the ion species from Gudmundsson 19,20 . Comparable quantitative comparisons between experimental and modeling results were previously published for hollow cathode dc discharges in H 2 -Ar mixtures by Méndez and coworkers 21,22 . Their glow discharge is operated at a high voltage of several hundred volts and the sheath is relatively thick.…”

Section: Introductionsupporting

confidence: 55%

Ion chemistry in H2-Ar low temperature plasmas

Sode

Schwarz-Selinger

Jacob

2013

Journal of Applied Physics

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A rate equation model is devised to study the ion composition of inductively coupled H 2 -Ar plasmas with different H 2 -Ar mixing ratios. The model is applied to calculate the ion densities n i , the wall loss probability of atomic hydrogen β H , and the electron temperature T e . The calculated n i 's of Ar + , H + , H + 2 , H + 3 and ArH + are compared with experimental results. Calculations were made for a total gas pressure of 1.0 Pa. The production and loss channels of all ions are presented and discussed in detail. With the production and loss rates the density dependence of each ion on the plasma parameters are explained. It is shown that the primary ions H + 2 and Ar + which are produced by ionization of the background gas by electron collisions are effectively converted into H + 3 and ArH + . The high density of ArH + and Ar + is attributed to the low loss to the walls compared to hydrogen ions. It is shown that the H + /H + 2 density ratio is strongly correlated to the H/H 2 density ratio. The dissociation degree is around 1.7 %. From matching the calculated to the measured atomic hydrogen density n H the wall loss probability of atomic hydrogen on stainless steel β H was determined to be β H = 0.24. The model results were compared with recently published experimental results. The calculated and experimentally obtained data are in fair agreement.

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Section: Introductionsupporting

confidence: 55%

Ion chemistry in H2-Ar low temperature plasmas

Sode

Schwarz-Selinger

Jacob

2013

Journal of Applied Physics

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“…Much of the H þ 3 flux is from the reaction with H 2 of low energy H þ 2 produced by energetic electrons injected into the low electric field regions of the negative glow. Because of this behavior and the very much simplified model, it is desirable to extend to hydrogen the recent examination of this region by Donkó and coworkers; 60 to utilize the results of recent studies of electron-ion recombination of hydrogenic ions by Glosík et al, 66 Kreckel et al, 67 and others; and to consider the low-energy, ion-molecule reactions in hydrogen examined by Méndez et al 68 Critical to such a model is the calculation of the self-consistent electric field that governs the ion motion and the competition among electron-ion recombination, ambipolar diffusion, etc.…”

Section: Discussionmentioning

confidence: 99%

The cathode-fall of low-pressure hydrogen discharges: Absolute spectral emission and model

Jelenković

Phelps

2011

Physics of Plasmas

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Account of nonlocal ionization by fast electrons in the fluid models of a direct current glow discharge Phys. Plasmas 19, 093503 (2012) Long range temporal correlation in the chaotic oscillations of a dc glow discharge plasma Phys. Plasmas 19, 082313 (2012) Numerical simulation of operation modes in atmospheric pressure uniform barrier discharge excited by a sawtooth voltage Phys. Plasmas 19, 083505 (2012) Extraction of negative ions from pulsed electronegative capacitively coupled plasmas Absolute excitation probabilities from very low to moderate-current hydrogen discharges in parallel-plane geometry are measured and used to test models. Relative emission data are obtained for the H a line, the H 2 (a 3 R ! b 3 P) near-UV continuum, and the H 2 G 1 R ! B 1 P þ u À Á band at pressures of 0.5 and 2 Torr, a 1.05 cm gap, and voltages from 300 to 900 V. Electron behavior is traced using the first negative (A 2 R g ! X 2 P u , v 00 ¼ 0 ! v 0 ¼ 0) band of N þ 2 by adding 2% N 2 . Relative measurements of H a , H 2 near-UV, and N 2 1st negative emission are placed on a absolute scale by normalization to published measurements and Boltzmann calculations of electron excitation. Emission probabilities calculated using a multi-beam kinetics model for the electrons, H þ , H þ 2 , H þ 3 , H À , H, and H 2 are compared with the calibrated experiments. Fast H atoms are calculated to produce H a excitation that is comparable with that of electrons. The calculated emission intensities for H a and H 2 near-UV continuum are within a factor of three of the absolute measurements for a range of 5000:1 in current and 4:1 in hydrogen pressure. Calculations at 2 Torr show that most of the space charge electric field responsible for the cathode fall is produced by H þ 3 ions. [

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“…The three panels display the regions of interest. Note the different scales in the intensity of the signals (vertical axis) of the left panel and the other ones, which is due, not only to the efficient production of H 2 as major stable product of the discharge, but also to the higher detection efficiency at low masses, commonly found in quadrupole mass spectrometers [34,43]. In what follows, only relative variations of signal intensities are taken into account and, hence, the diverse efficiencies for the various species are not significant.…”

Section: Methodsmentioning

confidence: 99%

Plasma diagnostics and device properties of AlGaN/GaN HEMT passivated with SiN deposited by plasma-enhanced chemical vapour deposition

Romero¹,

Sanz²,

Tanarro³

et al. 2010

J. Phys. D: Appl. Phys.

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In this work, silicon nitride thin films have been deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD) on both silicon samples and AlGaN/GaN High Electron Mobility Transistors (HEMT) grown on sapphire substrates. Commercial parallel-plate RF plasma equipment has been used. During depositions, the dissociation rates of SiH 4 and NH 3 precursors and the formation of H 2 and N 2 have been analysed by mass spectrometry as a function of the NH 3 /SiH 4 flow ratio and the RF power applied to the plasma reactor. Afterwards, the properties of the films and the HEMT electrical characteristics have been studied. Plasma composition has been correlated with the SiN deposition rate, refractive index, H content and the final electric characteristics of the passivated transistors.

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On the ionic chemistry in DC cold plasmas of H2 with Ar

Cited by 18 publications

References 49 publications

Ion chemistry in H2-Ar low temperature plasmas

Ion chemistry in H2-Ar low temperature plasmas

The cathode-fall of low-pressure hydrogen discharges: Absolute spectral emission and model

Plasma diagnostics and device properties of AlGaN/GaN HEMT passivated with SiN deposited by plasma-enhanced chemical vapour deposition

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