First stages in the formation of ultra thin nickel layers on Cu(111) and Ge(111) and dissolution:: an AES comparative study

In this paper we present a low energy electron diffraction (LEED)-Auger electron spectroscopy (AES) comparative study of slow deposition of nickel vapor onto clean Cu(111) and Ge(111) substrates at room temperature and dissolution of the as-deposited ultrathin Ni layers at higher temperature. The main results of the present investigation are: (i) the growth of nickel on Cu(111) occurs via a layer-by-layer or a simultaneous multilayers growth mode and epitaxial pseudomorphic Ni layers are obtained in agreement with previous studies, and (ii) the growth of nickel on Ge(111) is described considering the partial formation of a surface compound and/or Ge surface segregation during deposition. Annealings of the as-deposited Ni layers confirm these results: when the mass transport is high enough a complete dissolution of nickel in copper is observed while superficial nickel germanide formation is obtained on germanium according to the phase diagrams of the systems. (C) 2000 Elsevier Science B.V. All rights reserved.