β-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°C. The β-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 β-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 β-hydride elimination process is the rate limiting step in the desorption of ethylene and is first order in the ethyl group coverage. © 1993.