Chemical reactions of triethylantimony on GaAs(100)

Abstract

The surface chemistry of triethylantimony was studied on GaAs(100) using thermal desorption spectroscopy, static secondary ion mass spectroscopy, and x-ray photoelectron spectroscopy. Triethylantimony is reversibly adsorbed following exposures at 160 K. The saturation coverage at 160 K is approximately 0.3 monolayers. Following triethylantimony exposure at 330 K, ethylene, the major hydrocarbon reaction product, desorbs from the GaAs(100) surface during thermal desorption spectroscopy experiments with a peak temperature of 569 K. This indicates a β-hydride elimination reaction is responsible for the elimination of ethyl groups from the surface. Additionally, a small amount of ethyl radicals desorb from the surface. Our results indicate that ethyl groups migrate to Ga sites and then undergo a β-hydride elimination reaction at these sites. For saturation coverage (0.3 monolayers), 90% of the triethylantimony is irreversibly adsorbed. Exposures at 675 K led to adsorbed Sb atoms as well as GaSb formation. The reactive sticking coefficient of triethylantimony is low, 4×10−4, and decreases as the surface becomes Sb rich. Eventually, adsorption of triethylantimony ceases at 675 K, indicating self-limiting adsorption.