PHOTOEMISSION-STUDY OF THE GADOLINIUM GAAS(100) INTERFACE WITH SYNCHROTRON-RADIATION/

Soft-X-ray photoemission spectroscopy was used to characterize the Gd/ GaAs(100)-interface formation at room temperature. At low Gd coverage (< 1 Angstrom), the interface is near-abrupt, because no evidence of r eaction is observed. With increasing Gd coverage, photoemission signal s from chemically reacted product at the interface are observed, causi ng some intermixing between the overlayer and the substrate. For As at oms, they remain near the interface and have little diffusion. Ga atom s, however, are not kept near the interface, and they can diffuse into the Gd overlayer and segregate onto the surface instead. From the obs erved variations with metal coverage of binding energies and relative intensities of photoemission signals from the reacted layer, a profile of the interface structure is proposed, and some parameters (decaying length, segregation density and solution density, etc.) have been obt ained. The results show that the deposition of Gd onto the GaAs(100) s urface induces limited substrate disruption except for some diffusion and segregation of Ga atoms into the metal overlayer. This paper demon strates that the disruption and epitaxial growth are not mutually excl usive in the Gd/GaAs(100) system.