The morphology and reconstruction of a vicinal Si(111) surface during Si molecular beam epitaxy by reflection high-energy electron diffraction was investigated in conjunction with pulsed (0.25 to 1s) low-energy (80–150eV) Kr+ ions in the dose range of 1011 to 1012/cm2. Pulsed ions were found to increase reflection high-energy electron diffraction specular beam intensity. This corresponded to an improvement of the surface smoothness during molecular beam epitaxial growth. The maximum intensity enhancement was found when the pulsed ion beam was turned on at a fractional surface coverage of 0.8 and a substrate temperature of about 400C. It was revealed that pulsed ion beam action induced a (5 x 5) to (7 x 7) superstructure phase transition. As the substrate temperature increased, the area of (7 x 7) reconstruction induced by ion beam action was found to expand; reaching a maximum at 400C. Above this temperature, the (7 x 7) reconstruction area tended to the value for Si molecular beam epitaxy without ion beam action. A simulation model of molecular beam epitaxial growth was presented which included surface reconstruction under low-energy pulsed ion beam action. It was suggested that the ion beam induced a (5 x 5) → (7 x 7) superstructure phase transition which permitted a decrease in the activation energy for adatom diffusion and improved the surface smoothness. The modelling results were in good agreement with experimental data at a different surface coverage, with the temperature of the substrate being the same for both single- and multi-pulse ion beams.

Surface Reconstruction Induced by a Pulsed Low-Energy Ion Beam during Si(111) Molecular Beam Epitaxy. A.V.Dvurechenskii, V.A.Zinovyev, V.A.Markov, V.A.Kudryavtsev: Surface Science, 1999, 425[2-3], 185-94