Schottky barrier formation at Pd, Pt, and Ni/Si(111) interfaces

Abstract

Synchrotron radiation photoemission measurements have been used to study Schottky barrier formation and the electronic structure of interfaces of Si with Pt, Pd, and Ni. High resolution photoemission spectroscopy of the Si 2p core levels has been used to monitor changes in band bending (or Schottky barrier height) when the metal is deposited on the Si surface. Barrier height measurements on sputter-cleaned (i.e., ion bombardment and subsequent annealing) and on heat-cleaned (i.e., annealing only) samples show no effect of the ion bombardment on the rate of change in barrier height with coverage. The Schottky barrier height reaches a saturation value within 1 Å metal coverage for Pt and Ni, but it requires ∼4.5 Å for Pd. For the Ni/Si interface, measurements of the valence electronic structure indicate that the Schottky barrier height is unrelated to the existence of a metallic character of the contact.