GROWTH OF EPITAXIAL CO LAYERS ON SB-PASSIVATED GAAS(110) SUBSTRATES

The role of Sb in the formation of the Co/GaAs(110) interfaces has bee n investigated by angular photoelectron diffraction (PD), synchrotron- radiation (SR) core-level photoemission and low-energy electron diffra ction. We find that Co forms a metastable bce phase on GaAs(110), with its principal crystallographic axes parallel to the substrate. From p olar-angle-scanned PD, we determine an outward expansion of up to 14% of the lattice constant perpendicular to the surface, for epitaxial Co films grown on nontreated substrates. By Sb passivation of the GaAs(1 10) surface prior to the Co deposition, the epitaxial quality of the m etallic overlayer is improved. The resulting Co phase is found to grow in a perfect bcc (110) orientation with a minor disruption of the sub strate underneath and a reduced intralayer spacing outward expansion o f less than 1%.