OXYGEN-ADSORPTION OBSERVED DURING THE EPITAXY OF V(110) ON THE (11(2)OVER-BAR0) ALPHA-AL2O3 SURFACE

Oxygen structures (c(6 x 2) and p(11 x 4)) have been observed during t he epitaxy of V(110) on a (1120BAR) alpha-Al2O3 surface. The p(11 x 4) -O structure is reported for the first time. Results based on Auger sp ectroscopy show that the oxygen coverage for the p(11 x 4) structure m ust be approximately 20% smaller than that for the c(6 x 2) structure. In-plane parameters deduced from RHEED patterns observed on the initi al sapphire surface are in accordance with the parameters of the oxyge n sub-lattice of sapphire. A clean V(110) surface is obtained after se veral hours of successive annealing and ion bombardment.