Photochemistry of silicon compounds.  IV.  Mercury photosensitization of disilane

Pollock, T. L.; Sandhu, H. S.; Jodhan, A.; Strausz, O. P.

doi:10.1021/ja00785a005

Cited by 91 publications

(17 citation statements)

References 3 publications

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“…Ethene 31,34,36-38 and propene 31,34 are known to be good free radical scavengers. This fact is in agreement with work done by Pollock et al 37 in which they found that the trapping reaction of silyl radical (ÁSiH 3 ) by ethene is two to three orders of magnitude faster than its addition to alkyl radicals and also more rapid than the addition reaction of the trimethylsilyl radical to ethene. Among these radicals, some are methylsubstituted silyl radicals [e.g., (CH 3 ) 3 SiÁ, (CH 3 ) 2 HSiÁ], others are (silyl-substituted) alkyl radicals] e.g., (CH 3 ) 2 SiHCH 2 Á, ÁCH 3 ].…”

Section: Radical Recombination Reactionssupporting

confidence: 93%

Effect of trimethylsilane pressure on hot-wire chemical vapor deposition chemistry using vacuum ultraviolet laser ionization mass spectrometry

Toukabri

Shi

2013

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

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Detecting free radicals during the hot wire chemical vapor deposition of amorphous silicon carbide films using single-source precursors J. Vac. Sci. Technol. A 24, 542 (2006); 10.1116/1.2194023 Vacuum ultraviolet mass-analyzed threshold ionization spectroscopy of hexafluorobenzene: The Jahn-Teller effect and vibrational analysisIn this study, the authors investigated the effect of sample pressure on the reaction chemistry of trimethylsilane (TriMS) in the hot-wire chemical vapor deposition (CVD) process. The secondary gasphase reaction products were examined in a reactor with varying TriMS pressures. The reaction products were analyzed using a laser ionization source with a vacuum ultraviolet wavelength of 118 nm, coupled with mass spectrometry. By increasing TriMS pressure, methane formation was observed. To our knowledge, this is the first successful use of either open-chain alkylsilanes or four-membered-ring (di)silacyclobutane molecules as an independent precursor gas in the hot-wire CVD reactor to achieve methane formation. Our results showed that methane was formed mainly from the radical chain reactions with minor contributions from molecular elimination. The increase in the sample pressure also led to the formation of other small hydrocarbon molecules including acetylene, ethene, propyne, and propene. The formation of hydrogen molecules was enhanced when the sample pressure was increased. In addition, the change in the sample pressure had a direct effect on the radical recombination and disproportionation reactions. This is reflected in the different behavior assumed by the main products from these two types of reactions, i.e., tetramethylsilane, hexamethyldisilane from the former, and three methyl-substituted disilacyclobutanes from the latter. The trapping of free radicals resulting from the in-situ produced ethene and propene molecules is responsible for the observed difference.

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Section: Radical Recombination Reactionssupporting

confidence: 93%

Effect of trimethylsilane pressure on hot-wire chemical vapor deposition chemistry using vacuum ultraviolet laser ionization mass spectrometry

Toukabri

Shi

2013

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

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“…In this case, a simple approach consists to balance the creation and loss rate of AB* in order to derive the effective rate constants kl,eff for the total reaction and k~,~f f and ks,eff for the production of C + D or AB, 1: BECERRA et al [204]; m: the association excited product Si3HT should easily dissociate along the proposed exothermic channel and little pressure dependence is expected, as opposed to the reaction of SiH with SiH4 producing Si2H: for which the dissociation into SizH~fHz is nearly thermoneutral; n: POLLOCK et al [205]; 0: ITABASHI et al [206]; p: LOH et al [207]; q: KosHI et al [208] +SiHz where Po and To are standard pressure and temperature. Such expressions can be used to fit experimental data obtained at different pressures.…”

Section: A + B -A B * -C + D mentioning

confidence: 99%

Cross‐Sections, Rate Constants and Transport Coefficients in Silane Plasma Chemistry

Perrin

Leroy

Bordage

1996

Contrib. Plasma Phys.

342

260

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This paper presents a critical review of the basic data concerning the physics and chemistry of low pressure SiH4 glow discharges used to deposit hydrogenated amorphous silicon films (a&: H). Starting with an updated table of thermochemical data, we analyze the gas-phase elementary processes consisting of i) electron-molecule collisions, ii) ion-molecule collisions, iii) neutral-neutral collisions, iv) other electron and ion collisions involving electron-ion and ion-ion recombination, electron attachment on radicals and detachment of anions, and v) cluster growth kinetics in dusty plasmas. Experimental data or theoretical estimates are given and discussed in terms of cross-sections, collision and reaction rate constants, and transport coefficients. We also analyze the surface processes and reaction probabilities of ions, radicals and molecules.

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“…Several studies have claimed that ethene efficiently traps methylsilyl radicals. [28][29][30][31] Neudorfl and Strausz 29,30 studied the pyrolysis of MMS and DMS in the presence of ethene as a radical scavenger. In the presence of ethene, they found that the products generated from the free radical chain reaction are completely suppressed, while the ones evolved from the reaction of silene−silylene intermediates are still detected but with reduced yield.…”

Section: Intensity (Au)mentioning

confidence: 99%

“…This observation was obtained by several other studies when using ethene as a free-radical scavenger. 24,25,28,31 Therefore, ethene can react with both silyl radicals and silylene species. The trapping adduct formed from the reaction of ethene with the parent silyl (·SiH 3 ) radical and silylene (:SiH 2 ) species is ethylsilane and silacyclopropane, respectively.…”

Section: Intensity (Au)mentioning

confidence: 99%

Effect of pressure on the gas-phase chemistry when using monomethylsilane and dimethylsilane in hot-wire chemical vapor deposition

ToukabriRim

ShiYujun

2015

Can. J. Chem.

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The effect of source gas pressure on the gas-phase reaction chemistry of dimethylsilane (DMS) and monomethylsilane (MMS) in the hot-wire chemical vapor deposition process has been studied by examining the secondary gas-phase reaction products in a reactor using a soft laser ionization source coupled with mass spectrometry. For DMS, the increase in sample pressure has resulted in the formation of small hydrocarbons, including ethene, acetylene, propene, and propyne. This leads to a switch from silylene dominant chemistry to a free radical dominant one with the pressure increase at low filament temperatures of 1200 and 1300°C. At the lower pressure of 0.12 Torr, the formation of 1,1,2,2-tetramethyldisilane by dimethylsilylene insertion reaction into the Si-H bond in DMS is favored over trimethylsilane produced from a free radical recombination reaction for a short reaction time. However, when the pressure is increased by 10 times, the gas-phase chemistry becomes dominated by the formation of trimethylsilane. We have demonstrated that trapping of the corresponding active intermediates by the small hydrocarbons produced in situ is responsible for the observed switch. In the study with MMS, the gas-phase chemistry is dominated by the formation of 1,2-dimethyldisilane and 1,3-disilacyclobutane at both pressures of 0.48 and 1.2 Torr. Unlike DMS, the gas-phase reaction chemistry with MMS does not involve free radicals, which are the precursors to produce small hydrocarbons. The absence of small hydrocarbons formed in situ with MMS explains the preservation in chemistry upon the increase in pressure when MMS is used as a source gas.Résumé : On a étudié dans un réacteur l'effet de la pression du gaz source sur la réaction en phase gazeuse du diméthylsilane (DMS) et du monométhylsilane (MMS) par un procédé de dépôt chimique en phase vapeur à fil chaud, en étudiant les produits secondaires dans la phase gazeuse au moyen d'un laser de faible puissance utilisé comme source d'ionisation et couplé avec un spectromètre de masse. Dans le cas du DMS, l'augmentation de la pression de l'échantillon a entraîné la formation d'hydrocarbures légers, notamment l'éthène, l'acétylène, le propène et le propyne. On en déduit que l'environnement chimique où la formation du silylène prédomine passe à un environnement chimique où la formation de radicaux libres prédomine dans lequel une augmentation de la pression s'est produite à de basses températures du filament (1200 et 1300°C). À la pression la plus faible (0,12 Torr), pendant un temps de réaction court, la formation du 1,1,2,2-tétraméthyldisilane par réaction d'insertion du diméthylsilylène dans le lien Si−H du DMS a été favorisée, par rapport à la formation du triméthylsilane issu de la réaction de recombinaison de radicaux libres. Toutefois, lorsque la pression était décuplée, la formation en phase gazeuse du triméthylsi-lane était prédominante. Nous avons démontré que le piégeage des intermédiaires réactifs par les hydrocarbures légers produits in situ est responsable du changement obse...

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Photochemistry of silicon compounds. IV. Mercury photosensitization of disilane

Abstract: The room-temperature mercury 6(1 23Pi) photosensitization of disilane produces H2, SiH4, Si3H8, Si4Hio, and a solid deposit. From detailed kinetic studies using deuterium-labeling techniques and scavengers such as NO and C2H4 it has been established that the sole primary step is Hg 6(3 4

Cited by 91 publications

References 3 publications

Effect of trimethylsilane pressure on hot-wire chemical vapor deposition chemistry using vacuum ultraviolet laser ionization mass spectrometry

Effect of trimethylsilane pressure on hot-wire chemical vapor deposition chemistry using vacuum ultraviolet laser ionization mass spectrometry

Cross‐Sections, Rate Constants and Transport Coefficients in Silane Plasma Chemistry

Effect of pressure on the gas-phase chemistry when using monomethylsilane and dimethylsilane in hot-wire chemical vapor deposition

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