PHOTOEMISSION-STUDY OF GD GAAS(110) INTERFACE

The behavior of Gd/GaAs(110) interfaces formed at room and low (100 K) temperatures was investigated by photoemission from Ga 3d, As 3d, Gd 4f levels and low energy electron diffraction (LEED). Core level bindi ng energy shifts due to upward band bending were observed starting fro m the minimal Gd coverages (0.03 ML). It was found that the:band bendi ng completes only after the metallization of the interfaces. It is sug gested that two different mechanisms are involved in Schottky-barrier formation Fermi level pinning by the defect states and. metal-induced gap states. Experiments have shown that the deposition of Gd both at r oom and low temperatures leads to the reactive interface formation. It was found that reacted components in the photoemission spectra become observable already at 0.03 ML coverage. In Ga 3d and As 3d photoemiss ion spectra these components move to lower binding energies (as well a s the unreacted ones) with increasing Gd coverage. Investigations by t he LEED technique demonstrated essentially disordered structure format ion both at low and room temperatures. Temperature induced changes in the interface growth mode were observed in the present study. It was f ound that at 300 K the overlayer growth mode shows cluster features wh ereas at 100 K the mode is similar to the Stranski-Krastanov one.