Ligand lability of triethylgallium on GaAs(100)

We report direct evidence for dissociative adsorption and recombinative desorption of triethylgallium on GaAs(100). Deuterated and undeuterated triethylgallium were used to investigate two distinct ethyl species produced by chemisorption of triethylgallium on GaAs(100): ethyl ligands bound to the GaAs surface and those in chemisorbed ethylgallium species. Deuterium labeling verified that chemisorbed ethyl ligands exchange at temperatures as low as 205 K, for which the GaAs surface serves as an intermediate adsorption site. Ligand exchange was also observed for physisorbed multilayers of triethylgallium for temperatures at or below 180 K. Ligand labeling experiments were also used to demonstrate that following dissociative adsorption, diethylgallium is the only adsorbed ethylgallium species that can lead to recombinative desorption; decomposition of adsorbed diethylgallium prohibits recombinative desorption. Rapid and continuous ligand exchange on the GaAs surface and walls of the vacuum chamber at temperatures of 300 K and above was also observed.