Ligand lability of triethylgallium on GaAs(100)

We report direct evidence for dissociative adsorption and recombinative des orption of triethylgallium on GaAs(100). Deuterated and undeuterated trieth ylgallium were used to investigate two distinct ethyl species produced by c hemisorption of triethylgallium on GaAs(100): ethyl ligands bound to the Ga As surface and those in chemisorbed ethylgallium species. Deuterium labelin g verified that chemisorbed ethyl ligands exchange at temperatures as low a s 205 K, for which the GaAs surface serves as an intermediate adsorption si te. Ligand exchange was also observed for physisorbed multilayers of trieth ylgallium for temperatures at or below 180 K. Ligand labeling experiments w ere also used to demonstrate that following dissociative adsorption, diethy lgallium is the only adsorbed ethylgallium species that can lead to recombi native desorption; decomposition of adsorbed diethylgallium prohibits recom binative desorption. Rapid and continuous ligand exchange on the GaAs surfa ce and walls of the vacuum chamber at temperatures of 300 K and above was a lso observed. (C) 2000 Elsevier Science B.V. All rights reserved.