Comparative study of Ag growth on GaAs(001) and (110) surfaces

Through high-resolution electron energy loss spectroscopy, the Ag/GaAs(001) 2x4 and Ag/GaAs(001) 4x2 interfaces are investigated. The results are comp ared both with each other and with those previously obtained for the Ag/GaA s(110) interface. X-ray photo emission spectroscopy and scanning tunneling microscopy have also been employed. As the Ag film grows, it forms 3D islan ds (Volmer-Weber growth mode) that, with respect to those of the (110) surf ace, are more in number and flatter. Moreover, at odds with the ( 110) surf ace, a continuum of states in the energy range of the gap forms at the earl y stage of junction formation. However. the band-gap losses come from the p erimeter of the islands as in the (110) case. (C) 1998 Elsevier Science B.V . All rights reserved.