Kinetics and mechanism of atomic layer epitaxy of GaAs using trimethylgallium

The desorption time constant of carbon-related species from clean GaAs surfaces exposed to trimethylgallium (TMGa), measured by in situ Auger electron spectroscopy, is of the order of 100 s in the temperature range where atomic layer epitaxy of GaAs takes place. A set of rate equations based on the adsorbate-inhibition model using this desorption time constant is shown to reproduce atomic layer epitaxy growth results: the GaAs growth rate dependence on the TMGa supply duration and the growth rate of the double TMGa pulse experiments with purge time in between two TMGa pulses. The origin of the remaining discrepancies is discussed.