Stranski-Krastanov growth of Si on SiC(0001)

The molecular beam epitaxial growth of Si on SiC(0001), exhibiting a Strans ki-Krastanov mode, was investigated by reflection high-energy electron diff raction. Several surface superstructures were observed in the initial stage of growth. After exceeding a critical coverage, Si island formation sets i n. Under near-equilibrium conditions, the critical coverage was 1.4 monalay ers and corresponds to the occurrence of a 3 x 3 superstructure remaining a s a wetting layer after the island formation. island formation at high depo sition rates (R) and low temperatures (T) is kinetically delayed, which can be described as function of R and the diffusivity D by a relationship t(c) proportional to rootR/D. Si islands, which were relatively uniform size of several nm with a density of 10(11) cm,were obtained under these condition s. At fewer R values the critical thickness is only a function of T, indica ting that the incorporation time of adatoms is the relevant time scale for surface diffusion. Ordered arrays of small dots were also grown on vicinal surfaces at higher T and lower R values, which can be attributed to a lower diffusivity at step edges, acting as perfect sinks for the Si adatoms. Fur thermore, two different kinds of islands were found with a (111)/(0001) and (110)/(0001) epitaxial relationship. (C) 2000 Elsevier Science B.V. All ri ghts reserved.