Mechanistic Diversity in the Reactive Adsorption of Chlorine Trifluoride on Monohydrogenated Silicon

Abstract

We present first-principles molecular dynamic simulations of chlorine trifluoride impinging upon the monohydrogenated Si{001} surface. Our computed trajectories reveal a rich variety of reactive adsorption events, most of which differ considerably from the behaviour predicted in previous quasistatic transition state calculations for the dihydrogenated surface. In addition to reactions involving the abstraction of adsorbed hydrogen, we find that direct interaction of the molecule's equatorial fluorine atom with silicon atoms as deep as the third layer may also lead to reactive adsorption. Amongst the surface defects induced by these processes, we find cationic bridges of Si--H--Si or Si--F--Si type; anionic motifs of Si--Si--F type; and silicon dangling bonds, which may be of cationic, anionic, or radical character. Chlorine monofluoride is evolved in the majority of reactive trajectories, with hydrogen fluoride, hydrogen chloride, and difluorochlorate species generated on occasion.