Reactions of He+, Ne+, and Ar+ with CH4, C2H6, SiH4, and Si2H6

Abstract

The rate coefficients and product‐ion distributions for the reactions of He⁺ and Ar⁺ with silane and disilane have been measured in a drift tube, typically for collision energies of 0.01–1 eV. The total charge‐exchange rate coefficients are found to be roughly independent of E/N, or collision energy, and are about equal to the Langevin values for the reactions of He⁺ with SiH₄ and C₂H₆ and Ar⁺ with CH₄ and C₂H₆. The He⁺ rate coefficients on CH₄ and Si₂H₆, and the Ne⁺ rate coefficients on SiH₄ and Si₂H₆ are 50% to 80% of the Langevin values, while the Ar⁺ rate coefficients on SiH₄ and Si₂H₆ are much smaller. Product ions tend to be hydrogen poor with very infrequent breaking of the C–C or Si–Si bonds. Furthermore, hydrogen stripping is more severe for the silanes than the alkanes. These product‐ion distributions bear no resemblance to the product‐ion distributions of either photoionization or electron collisional ionization.