Studies of silicon cluster–metal atom compound formation in a supersonic molecular beam

Abstract

The first observation of a reaction between a metal atom and silicon in a supersonic jet to form metal atom silicon clusters is reported. Using the technique of laser vaporization supersonic expansion with metal carbonyl seeded carrier gas, clusters of the form MSin have been detected by ArF and KrF laser photoionization time-of-flight mass spectrometry. Three transition metals have been investigated, Cr, Mo, and W. The dominant product cluster peaks observed in the mass spectra obtained for all three metals corresponds to identical but remarkable cluster stoichiometries. The dominant peaks have formulas given by MSin where n=15 and n=16. The metal–semiconductor clusters are relatively more stable towards photofragmentation than the bare silicon cluster of the same size. The observation of these new species may be relevant to reactions which occur at the interface between a silicon wafer and deposited metals.