One monolayer of Sb or Bi used as a buffer layer preventing oxidation of InP

Abstract

One monolayer of Sb or Bi has been used as a buffer layer to protect InP surfaces against the oxidation. We have used photoemission spectroscopy to estimate the oxide fraction of In and the surface Fermi level position. We find that one monolayer of Sb or Bi reduces the oxidation of underlying InP at least by more than two orders of magnitude. For passivated surfaces with one monolayer of Sb or Bi, the surface Fermi level remains pinned at the conventional pinning level 0.45 eV below the conduction-band minimum (CBM) even for oxygen exposures above 1×107 L, whereas without the Sb or Bi overlayers, the surface Fermi level is near the CBM for the same O2 exposure. Core-level studies indicate that the Sb or Bi overlayer must be itself oxidized before there is strong oxidation of the InP.