title: Electron-impact ionization of silicon tetrachloride (SiCl4).
abstract: We measured absolute partial cross sections for the formation of various singly charged and doubly charged positive ions produced by electron impact on silicon tetrachloride (SiCl4) using two different experimental techniques, a time-of-flight mass spectrometer (TOF-MS) and a fast-neutral-beam apparatus. The energy range covered was from the threshold to 900 eV in the TOF-MS and to 200 eV in the fast-neutral-beam apparatus. The results obtained by the two different experimental techniques were found to agree very well (better than their combined margins of error). The SiCl3(+) fragment ion has the largest partial ionization cross section with a maximum value of slightly above 6x10(-20) m2 at about 100 eV. The cross sections for the formation of SiCl4(+), SiCl+, and Cl+ have maximum values around 4x10(-20) m2. Some of the cross-section curves exhibit an unusual energy dependence with a pronounced low-energy maximum at an energy around 30 eV followed by a broad second maximum at around 100 eV. This is similar to what has been observed by us earlier for another Cl-containing molecule, TiCl4 [R. Basner, M. Schmidt, V. Tamovsky, H. Deutsch, and K. Becker, Thin Solid Films 374 291 (2000)]. The maximum cross-section values for the formation of the doubly charged ions, with the exception of SiCl3(++), are 0.05x10(-20) m2 or less. The experimentally determined total single ionization cross section of SiCl4 is compared with the results of semiempirical calculations.
authors.affiliation: Institut für Niedertemperatur-Plasmaphysik, Friedrich-Ludwig-Jahn-Strasse 19, D-17489 Greifswald, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Basner
authors.forename: M
authors.initials: M
authors.lastname: Gutkin
authors.forename: J
authors.initials: J
authors.lastname: Mahoney
authors.forename: V
authors.initials: V
authors.lastname: Tarnovsky
authors.forename: H
authors.initials: H
authors.lastname: Deutsch
authors.forename: K
authors.initials: K
authors.lastname: Becker