Pulsed trimethylgallium scattering from As-stabilized and Ga-stabilized surfaces

We investigated trimethylgallium (TMG) scattering from differently prepared Ga-stabilized GaAs(100) surfaces in comparison with that from an As-stabilized surface using a pulsed TMG beam. The obtained sticking coefficients of TMG as functions of TMG exposure indicated that, although clean Ga-stabilized surfaces are reactive to TMG, these surfaces are inactivated by TMG exposure of about 1.5 monolayers, independent of the stoichiometry of the prepared surface. The time-of-flight (TOF) spectrum of TMG scattered from the inactivated surfaces had only the component corresponding to scattering without surface residence, while the component with surface residence was dominant for scattering from an As-stabilized surface. This feature (without surface residence) is the same as that in the scattering from the mask surface of selective-area growth. The sticking coefficients and TOF spectra for Ga-stabilized surfaces were essentially the same for the various Ga coverages of the prepared surfaces. This suggested that the adsorbed methyl group rather than the surface Ga plays an important role in the inactivation of a Ga-stabilized surface.