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This work reports on the molecular beam epitaxy of high quality single crystal γ-Al2O3 thin films on Si(001) and Si(111) substrates. For both substrate orientations, film surfaces are found to be smooth and the oxide-Si interfaces are atomically abrupt without interfacial layers. Reflection high energy electron diffraction, x-ray diffraction, and transmission electronic microscopy characterizations were used to study the epitaxial relationship and the structural quality of the γ-Al2O3 layers depending on the Si substrate orientation. On Si(111), the alumina layers present a high crystalline quality. Evidence is made for a “two-for-three” unit cell indirect epitaxial relationship between γ-Al2O3 and Si(111). On Si(001), after a transition from cubic to hexagonal surface symmetry, the growth planes of γ-Al2O3 change from (001) to (111) leading to a bidomain growth. [ABSTRACT FROM AUTHOR]

In this Letter, we investigate manganese diffusion and the formation of Mn precipitates in highly strained, few monolayer thick, Mn-doped Ge wetting layers and nanometric size Ge quantum dot heterostructures embedded in silicon. We show that in this Ge(Mn)/Si system manganese always precipitates and that the size and the position of Mn clusters (precipitates) depend on the growth temperature. At high growth temperature, manganese strongly diffuses from germanium to silicon, whereas decreasing the growth temperature reduces the manganese diffusion. In the germanium quantum dots layers, Mn precipitates are detected, not only in partially relaxed quantum dots but also in fully strained germanium wetting layers between the dots. [ABSTRACT FROM AUTHOR]

Experiments and numerical simulations based on finite element modeling show that the x-ray intensity scattered by comparatively large nanostructures on a substrate is not simply related to their strain in experiments using either grazing incidence or exit because of multiple scattering effects. However, whatever the nanostructure size, the composition profiles are correctly extracted from grazing incidence multiwavelength anomalous scattering. These effects are illustrated for the structural analysis of Ge dome-shaped islands grown on Si(001). [ABSTRACT FROM AUTHOR]

Silicon nanowhiskers have been grown by molecular beam epitaxy on Si (111) by vapor-liquid-solid mechanism induced by gold droplets. Very thin Ge containing layers have been incorporated in Si nanowhiskers in order to grow SiGe heterostructures. Si and Ge growth rate in nanowhiskers, shape, and sidewall facets of nanowhiskers have been investigated by scanning electron microscopy and grazing incidence small angle x-ray scattering. Anomalous grazing incidence x-ray diffraction and transmission electron microscopy observations show a strong intermixing of Si with Ge in nanowhiskers and formation of SiGe heterostructures which are highly strained to Si. [ABSTRACT FROM AUTHOR]

0.5–10nm-thick single crystal γ-Al2O3 films was epitaxially grown, at high temperature, on Si(001) and Si(111) substrates using electron-beam evaporation techniques. Reflection High Energy Electron Diffraction studies showed that the Al2O3 films grow pseudomorphically on Si (100) up to thickness of 2nm. For higher thicknesses, a cubic to hexagonal surface phase transition occurs. Epitaxial growth and relaxation were also observed for Si(111). The film surfaces are smooth and the oxide–Si interfaces are atomically abrupt without interfacial layers. [Copyright &y& Elsevier]

Highlights • Composition of SiGe domes grown on vicinal Si(0 0 1) substrates were studied. • Synchrotron resonant x-ray diffraction measurements (Ge K-edge). • Elastic energy in islands grown on miscut substrates obtained for different Ge content. • Finite Elements Simulation points out that elastic energy is stored on new facets. Abstract We investigate here the influence of Si substrate miscut on the strain and elastic energy of Ge islands. We show how the morphology, composition and the elastic energy for 4 and 13 monolayers (ML) Ge islands grown at 600 °C and 730 °C on vicinal Si(0 0 1) surfaces change with miscut angles ranging between 0° and 10°. Scanning Tunneling Microscopy is used to determine the island morphology. Resonant x-ray diffraction near the Ge-K absorption edge allows the determination of the Ge concentration as well as the elastic energy stored on such structures from their dependency on the lattice parameter. Simulations using the Finite Elements Method indicate that the enlargement of the SiGe broad peak retrieved from the x-ray diffraction measurements is actually caused by the asymmetrical faceting induced by large miscut angles. Such faceting has a strong effect on island density and elastic energy, producing differences that are proportional to those observed in conditions with distinct SiGe content. [ABSTRACT FROM AUTHOR]