ATOMIC GEOMETRY OF Al-GaAs INTERFACES: GaAs (110)-p(1 multiplied by 1)-Al( theta ), 0 less than equivalent to theta less than equivalent to 8. 5 MONOLAYERS.

The atomic structure of Al on GaAs(110) is examined by soft x-ray photoemission spectroscopy (SXPS) and elastic low energy electron diffraction (ELEED) for coverages ranging from 0. 5 to 8. 5 monolayers (ML). The core level measurements show a heat-induced chemical shift of Al-2p to higher binding energy consistent with an Al-Ga replacement reaction and the formation of AlAs, and a decrease in emission from Al-2p and Ga-3d, indicating a penetration of Al in the lattice and thermal desorption or formation of islands of Ga freed by the replacement reaction. The ELEED multiple scattering analysis yields a correspondence between the initial experimental coverage and the structure of the interface.