RECONSTRUCTION, STEP-BUNCHING AND FACETING OF A VICINAL SI(100) SURFACE-INDUCED BY INDIUM ADSORPTION

The behavior of In overlayers deposited on a vicinal Si(100)-(2 x 1) surface at coverages between 0.5 and 25 monolayers (ML) and annealing temperatures between 250 and 600-degrees-C was studied by scanning tunneling microscopy (STM). The vicinal Si(100) surface was misoriented at 4-degrees toward [011], consisting of type-B (1 x 2) terraces of approximately 40 angstrom width with double atomic-layer steps. A (4 x 3) reconstruction was observed throughout the entire range of coverages and annealing temperatures. Although the original vicinal Si(100)-(2 x 1) surface was highly stable at annealing temperatures up to 700-degrees-C, step-bunching was induced by In adsorption at coverages greater-than-or-equal-to 0.5 ML, with the (100) terraces increasing to many times their original width. At coverages greater-than-or-equal-to 1 ML, the original step direction of [011BAR] changed to a zig-zag along low-index [010] and [001] directions, and the bunched steps became {130} facets. At annealing temperatures greater-than-or-equal-to 550-degrees-C, the {130} facets disappeared and the bunched steps were restored with meandering step directions. The destruction of the {130} facets was attributed to preferential desorption of In from these facets at 550-degrees-C. The (4 x 3) reconstruction persisted on the (100) terraces until the annealing temperature reached 600-degrees-C.