Rate constants for the reactions of SiH and SiH₂with SiH₄in a low-pressure SiH₄plasma

Abstract

From the laser-induced fluorescence measurements of the decay rate of SiH2 and SiH densities in the afterglow of a RF SiH4-Ar discharge, the rate constants for the reactions of SiH2 and SiH with SiH4 have been determined at pressures below 1 Torr. The rate constants obtained at 70 mTorr for the SiH2+SiH4 and SiH+SiH4 reactions are 4.3*10-11 and 4.8*10-11 cm3 S-1 per molecule, respectively. The rate constants of the two reactions decrease with decreasing pressure in a manner consistent with the high-pressure (>or=1 Torr) data available in the literature, indicating that, despite the present low-pressure conditions, the three-body association reactions producing, respectively, Si2H6 and Si2H5 are the dominant reaction channels. Measurements were also carried out using a SiH4-He discharge at 200 and 400 mTorr, giving rate constants somewhat smaller than those obtained using a SiH4-Ar discharge, possibly because of incomplete thermalization of SiH2 and SiH. The SiHx (x=0-3) production frequencies in SiH4 plasmas are discussed on the basis of the measured reaction rate constants.

Absorption spectroscopy of SiH2 near 640 nm

“…Most of the SiH 2 detection experiments using lasers 5,6,[11][12][13][14][15][16][17][18][19][20][21] have been performed on the à 1 B 1 (0, 2, 0) ϪX 1 A 1 (0, 0, 0) transition near 580 nm because of favorable Franck-Condon access and of the availability of an excellent dye in the corresponding range ͑Rhodamine 6G͒. Jasinski and coworkers [14][15][16] used frequency modulation and direct absorption techniques to monitor SiH 2 by detecting some rovibronic transitions of this band near 17250 cm Ϫ1 .…”

Cavity ring down study of the densities and kinetics of Si and SiH in a remote Ar-H2-SiH4 plasma

“…However, for conditions with high Ar ϩ flows and low SiH 4 The rate for this reaction is ϳ5ϫ10 Ϫ17 m 3 s Ϫ1 at the pressure of 0.2 mbar in the downstream region. 10 We expect the production of the hydrogen deficient Si 2 H 3 radical to be the dominant channel, because Si 2 H 5 * needs collisional stabilization. Some pressure dependence of the reaction rate has been observed by Nomura et al, 10 however, only for pressures higher than 0.25 mbar.…”

“…10 We expect the production of the hydrogen deficient Si 2 H 3 radical to be the dominant channel, because Si 2 H 5 * needs collisional stabilization. Some pressure dependence of the reaction rate has been observed by Nomura et al, 10 however, only for pressures higher than 0.25 mbar. For lower pressures the reaction rate appears to be constant.…”

“…For lower pressures the reaction rate appears to be constant. 10 Furthermore, charge transfer reactions between Ar ϩ and H 2 are taken into account because at lot of H 2 is produced in the SiH 4 dissociation processes. The ArH ϩ created by the charge transfer reaction can subsequently recombine with electrons.…”

“…In addition to mass spectrometry, [1][2][3] laser-induced fluorescence ͑LIF͒ based techniques, [4][5][6][7][8][9][10][11][12][13] ultraviolet absorption spectroscopy, [14][15][16] and intracavity 17,18 and infrared laser 19,20 absorption techniques, recently also cavity ring down absorption spectroscopy ͑CRDS͒ has been introduced in the field of SiH 4 plasmas. This sensitive, and relatively easy-to-apply diagnostic technique 21 has already been used for the detection of SiH 3 , [22][23][24] SiH 2 , 18 and nanometric Si-based particles.…”