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Adsorption and Dissociation of Trimethylgallium on Si(001): An Atomically Resolved STM Study.
Interim technical rept.,
WISCONSIN UNIV-MADISON DEPT OF CHEMISTRY
Pagination or Media Count:
The adsorption and dissociation of trimethylgallium TMG, GaCH33 on the Si001 surface has been studied using Scanning Tunneling Microscopy STM. The products of TMG dissociation are identified by their bonding location with respect to the underlying Si001 lattice, by bias dependent imaging and from detailed counting statistics. TMG is found to adsorb dissociatively at room temperature, yielding a methyl group and a dimethylgallium fragment bound to the surface. The GaCH32 groups produced by TMG dissociation are somewhat mobile at room temperature but are bonded more strongly near surface defects. Further dissociation yields gallium atoms on the surface, but no additional methyl groups. It is proposed that this second stage of reaction involves an intramolecular reaction to produce ethane, which desorbs into the gas phase, and gallium atoms. The gallium atoms are observed to arrange into single rows of gallium dimers which bind epitaxially on the Si surface. Heating the surface to 150 deg C completely decomposes the TMG fragments, yielding Ga atoms and CH3 groups.
APPROVED FOR PUBLIC RELEASE