In adsorption on Si(112) and its impact on Ge growth

Abstract

The change of the Si(112) surface morphology and structure induced by In adsorption, as well as the impact of In preadsorption on the growth kinetics and island morphology in Ge/Si(112) epitaxy, has been investigated by means of low-energy electron microscopy and diffraction. The intrinsically faceted Si(112) surface is smoothed upon In saturation. In contrast to a previously reported (7  1) reconstruction (reported in a recent work of Gai et al.), we observe a ½ð3 þ xÞ Â 1 superstructure, with x % 1=2. This is attributed to the coexistence of (3  1) and (4  1) building blocks with In vacancies. The presence of such vacancy rows is confirmed by the saturation of the ½ð3 þ xÞ Â 1 structure at about 0.8 monolayers. Ge growth on In-saturated Si(112) leads to the formation of 3-D islands, the morphology of which depends on the growth temperature. At 450 C, isotropic and dashlike islands are observed, whereas at 500 C, larger islands with a triangular outline are found. The orientation of the side facets of these triangular islands have been identified to be (111), (013), and (103). The dependence of the island density on the growth temperature indicates an enhanced Ge surface diffusion, as compared with growth on bare Si(112).

Ga and In adsorption on Si(112): Adsorption sites and superstructure

“…[1][2][3][4][5][6] Pre-adsorption of group-III metals on high-index Si surfaces provides an opportunity to strongly influence the morphology and arrangement of subsequently grown Ge nanostructures. [7][8][9][10] The adsorption of trivalent metals on Si surfaces may also be used for other applications which require surface passivation. For instance, in hybrid systems, where organic molecules are used for functionalization of semiconductor surfaces, the interaction between the substrate and the organic layer often needs to be reduced to obtain an ordered layer.…”

“…III A) and is in good agreement with previously reported results for the saturation coverage. 10 For the chosen deposition temperature the first-order superstructure spots end up at ±28% BZ, which is equivalent to a periodicity of N ≈ 3.5. The change of the superstructure spots with increasing coverage can also be seen from Fig.…”