BETA-HYDRIDE ELIMINATION-REACTION OF TRIETHYLGALLIUM ON GAAS(100) SURFACES

We have used a pulsed molecular beam and time-resolved mass spectrometry to Study the pyrolysis Of triethylgallium (TEGa)on GaAs(100) surfaces from room temperature to 450-degrees-C. The beta-hydride elimination pathway WhiCh produces ethylene and hydrogen competes with the direct desorption of the ethyl radicals. We have made a quantitative measure of the branching ratio and found that the beta-hydride elimination reaction is promoted by increasing the Ga/As stoichiometric ratio of the GaAs(100) surface, but becomes less important and independent of Ga coverage at higher temperatures. The beta-hydride elimination process is the rate limiting step in the desorption of ethylene and is first order in the ethyl group coverage.