It was noted that deposition of Na onto the 1 x 1 and 7 x 7 structures of (111) surfaces at room temperature produced a uniform layer with a weak metallic character. It was found that the binding energy of Na was greater for the 7 x 7 reconstruction than for the 1 x 1 reconstruction. The initial dipole moment was greater for Na on the 1 x 1 reconstruction. At coverages which were close to saturation, O initially went under the Na layer and formed a Na-O-Si complex, but later remained on top of it. The presence of Na caused a ten-fold increase in the initial sticking coefficient for O. When O was adsorbed at Na-covered surfaces at room temperature, and the specimen was later heated to 700C, the Na was removed from the surface while O formed SiO4 and SiO2. The effect of Na upon Si oxidation was essentially the same for the 7 x 7 and 1 x 1 structures.

C.Papageorgopoulos, M.Kamaratos: Journal of Physics - Condensed Matter, 1992, 4[8], 1935-45