Adsorption structure and silicide formation of Ba on the Si(001) surface

The behaviour of Ba atoms on the Si(001) surface was investigated by low-energy electron diffraction (LEED). An epitaxial silicide formation was observed for surfaces obtained both by deposition onto a substrate kept at 700 degrees C and by annealing at 600 degrees C after deposition at room temperature. These surfaces show [GRAPHICS] and [GRAPHICS] oblique patterns which have a unit cell close to six times and three times, respectively, as large as that of the BaSi2(111) surface. In addition to the (2 x 3), (2 x 1) and (2 x 4) structures at submonolayer coverage, a c(2 x 6) pattern was found. The two-fold periodicities of the (2 x 4) and (2 x 3) superstructures were determined to be parallel to the dimer direction using a single-domain Si(001)-(2 x 1) substrate. (C) 1998 Elsevier Science B.V. All rights reserved.