The IR multiphoton decomposition of PH 3SiH 4 mixtures sensitized by SiF 4

Abstract

The SiF 4-photosensitized decomposition of PH 3SiH 4 mixtures by IR radiation at 1025.3 cm −1 results in the formation of H 2, SiH 3PH 2 and Si 2H 6 in the gas phase and a solid deposit which is probably a mixture of polymeric PSi hydrides (PSiH x ). The effects of the composition of the reactant mixture, the pressure, the incident pulse energy and the presence of foreign gases (helium and nitrogen) on the course of the reaction were investigated. It was found that SiH 3PH 2 and Si 2H 6 are formed solely by the insertion of SiH 2 into PH 3 and SiH 4 respectively. A mechanism involving excitation of SiF 4 by absorption of radiation from the CO 2 laser beam and further collisional energy transfer between SiF 4 * and other molecules present in the system is in accord with the experimental results.