Epitaxy at Low Temperatures by Vapor Deposition of Pd, Pt, Rh, and Ir Observed by Field Ion Microscopy

The minimum substrate temperature required to form epitaxial layers by vapor deposition of Pd, Pt, Rh, and Ir on either Ir or Rh is determined to be 50, 100, 180 and 300°K, respectively, using a field ion microscope. This shows that the minimum temperature increases with the binding energy of the deposited metal. It is suggested that a very few jumps before an incident atom settles in a site, plus the possible displacement of an adsorbed atom by an incident one, will give epitaxy in these fcc metals. Any involvement of foreign adsorbed atoms in the formation of epitaxy is ruled out by the good (<10−9 Torr) vacuum used in these experiments.