Mechanism and Product Branching Ratios of the SiH₃ + SiH₃ Reaction

Abstract

The mechanism of the SiH 3 + SiH 3 reaction was studied by means of time resolved mass spectrometry. SiH 3 radical was generated by the ArF laser photolysis of C 2 Cl 4 in SiH 4 /He mixtures, and the products were detected by a low-energy electron impact ionization mass spectrometer. The rate constant derived from the decay rate of SiH 3 agreed well with that obtained from the rise rate of Si 2 H 6 . The overall rate constant of the reaction at 297 ( 2 K was determined to be (9.5 ( 3.5) × 10 -11 cm 3 molecule -1 s -1 . H 2 could also be detected as a product of the SiH 3 + SiH 3 reaction, and the yield of H 2 was measured to be 11 ( 4%. The other major product of the SiH 3 + SiH 3 reaction was SiH 2 , which rapidly reacts with SiH 4 to form Si 2 H 6 . It was confirmed by the addition of a large amount of H 2 as a SiH 2 -trapping reagent that Si 2 H 6 detected at p ) 5 Torr was exclusively produced via the SiH 2 + SiH 4 reaction. On the basis of these observations, the branching ratios for the decomposition of vibrationally excited Si 2 H 6 produced by the SiH 3 + SiH 3 reaction were estimated. These results were compared with conventional RRKM calculations.

UV Absorption Spectrum and Rate Constant for Self-Reaction of Silyl Radicals

“…2-4 times) larger than that which could be expected assuming the energy transferred in collisions with He atoms of 2 kJ mol -1 , 34 should be considered as reasonable given the uncertainties associated with the thermochemistry and the RRKM theory. 23,34 It should be noted, that if silylene formed in reaction 5 is the major absorbing species causing the residual absorption, then the observed pressure quenching of the residual absorption can be due both to the collisional vibrational relaxation of energized disilane molecules (1d) and collisional relaxation of excited HSiSiH 3 produced in reaction 1c.…”

“…In a subsequent paper, Matsumoto et al used another generator of chlorine atomssArF laser photolysis of C 2 Cl 4 . 23 The reaction monitoring was performed using electron impact ionization mass-spectrometry. The determined rate constant, (9.5 ( 3.5) × 10 -11 cm 3 molecule -1 s -1 , is in agreement with the previous results obtained using photolysis of CCl 4 as a source of chlorine atoms.…”

Rate constants of reactions involving SiH4as an association product from quantum Rice–Ramsperger–Kassel calculations

“…The conclusion of this brief survey is that a rather large and accurate reaction scheme is still mandatory to describe the homogeneous chemistry of small silicon hydrides over the wide range of temperature and pressure of interest for CVD and related processes. Moreover, since new experimental measurements of kinetic constants have been reported in recent years for a few important unimolecular and bimolecular reactions in the Si-H system, [8][9][10][11][12] a revision of some previously calculated kinetic parameters is also mandatory.…”

Determining a Line Strength in the ν3 Band of the Silyl Radical Using Quantum Cascade Laser Absorption Spectroscopy

“…However, these features have completely different time profiles, as can be seen in Figure and assignment of a time profile to a species allowed us to assign ambiguous cases. A key element that allowed us to make assignments was that SiH 3 is known to be rather long-lived with a half-life from 0.6 to 8 ms depending on the experimental conditions. ,− The unassigned species is observed to have a significantly faster decay, e.g., at SOC, with a half-life of 0.13 ms compared to greater than 0.8 ms for SiH 3 in our case.…”