HIGH-TEMPERATURE MBE GROWTH OF SI - DIRECT-CURRENT HEATING EFFECTS ON (111) AND (001) VICINAL SURFACES

The molecular beam epitaxial (MBE) growth model is extended to account for the electromigration of Si adatoms on both (001) and (111) Si surfaces. Step bunching is predicted to occur at the (111) surface when the heating current has step-down direction. Electromigration-induced formation of a major reconstruction domain at (001) Si is not expected when the growth process is controlled by step kinetics. When the process is controlled by surface transport, the vicinal surface is predicted to be dominated by either the 1 x 2 or 2 x 1 domain depending on the direction of the current. Microprobe reflection high-energy electron diffraction (mu-RHEED) observations of MBE growth of the (001) Si surface at temperatures of 750-900-degrees-C reveal preferential growth of the S(A) steps when the heating dc has a step-up direction. This is in contrast with the reported preferential growth Of S(B) steps at lower temperatures (400-600-degrees-C). The difference in the surface reconstruction is interpreted to indicate a transition from step-kinetics-controlled growth (at 400-600-degrees-C) to surface-diffusion-controlled growth (at 750-900-degrees-C).