THE OXIDATION OF THE BETA-RHOMBOHEDRAL BORON(111) SURFACE

We have studied the reaction of the (111) surface of beta-rhombohedral boron with O2 using X-ray photoelectron spectroscopy (XPS). The surfaces used were clean, as determined with XPS, and well-ordered, as determined with low-energy electron diffraction (LEED). The reaction with O2 proceeds in two stages, an initial uptake in oxygen followed by a much slower increase in surface oxygen. The net oxygen uptake is low at room temperature, reaches a maximum at 1000-1100 K, and then falls to a low level at 1273 K. To calibrate the oxygen coverage, XPS spectra of the O2 exposed surface were compared with spectra of B2O3 multilayers directly deposited on the surface. The comparison indicates that only submonolayer oxygen coverages are achieved under the conditions used.