Quantitative, nanometer-scale spatial resolution electron energy-loss spectroscopy (EELS) was used to map the composition of coherent islands grown by molecular-beam epitaxy of pure Ge onto Si(100). The Ge concentration XGe decreased, and the Ge/Si interface became more diffuse as the growth temperature increased from 400 to 700 °C. Integrated island volumes measured by atomic force microscopy (AFM) increased linearly with Ge coverage θGe, with slopes greater than 1. This result confirmed that island growth is faster than the Ge deposition rate due to Si interdiffusion. The linearity of the island volume versus θGe curves implied that XGe was independent of island size. XGe measured by EELS and AFM agree well with each other and correctly predicted the minimum dome size observed at each growth temperature.

Atomic force microscopy, transmission electron microscopy, and electron energy-loss spectroscopy have been used to study the size, structure, and composition of Ge/Si(100) islands grown by molecular beam epitaxy at 700 °C. It is found that the island evolution is qualitatively different than for growth at lower substrate temperatures. For growth at 1.4 ML/min, the composition is determined to be Si0.56Ge0.44 and appears to be independent of island size. A higher growth rate, 4.8 ML/min, kinetically stabilizes pure Ge pyramids prior to Si interdiffusion taking place. These pure Ge clusters are absent at the lower growth rate, demonstrating the influence of deposition rate on island evolution. This result indicates that deposition kinetics can control island composition and morphology without varying growth temperature and associated thermally activated processes.

Ge/Si(100) islands were found to coarsen during in situ annealing at growth temperature. Islands were grown by molecular-beam epitaxy of pure Ge and annealed at substrate temperatures of T=450, 550, 600, and 650 °C, with Ge coverages of 6.5, 8.0, and 9.5 monolayers. Three coarsening mechanisms operate in this temperature range: wetting-layer consumption, conventional Ostwald ripening, and Si interdiffusion. For samples grown and annealed at T=450 °C, consumption of a metastably thick wetting layer causes rapid initial coarsening. Slower coarsening at longer annealing times occurs by conventional Ostwald ripening. Coarsening of samples grown and annealed at T=550 °C occurs via a combination of Si interdiffusion and conventional Ostwald ripening. For samples grown and annealed at T⩾600 °C, Ostwald ripening of SiGe alloy clusters appears to be the dominant coarsening mechanism.

Si 1 − x Mn x alloy films of 50 nm thickness with 0.005⩽x⩽0.035 were grown by low-temperature molecular-beam epitaxy onto Si(100) substrates held at temperatures T in the range of 150°C⩽T⩽350°C. All films exhibit surface roughness with ∼20-nm-lateral and ∼1-nm-vertical length scales. This roughness is random for films with small x grown at the lower end of the temperature range. Films with larger x grown at higher T exhibit roughness organized into ⟨110⟩-oriented cluster arrays centered on shallow surface depressions. This organized roughness correlates with the formation of subsurface complexes of four {111} planar defects or “funnel” defects. Mn-rich, nanometer-sized nodules form near the bottom of the Si1−xMnx film and seed the formation of vertical, amorphous nanopipes. For growth of small x films at the lower end of the temperature range, these vertical nanopipes extend to the surface. In contrast, films with larger x grown at higher T form funnel defects which appear to emanate from the vertical nanopipes. Regardless of growth conditions, the Mn-rich nodules appear crystalline and do not correlate to any known Si–Mn phase. Ion channeling indicates that up to 90% of the Mn is substitutionally incorporated for samples with x=0.005. Although the substitutional fraction decreases with increasing x, the substitutional content increases. Our results indicate that Mn may be substitutionally incorporated in epitaxial thin films at concentrations of several orders of magnitude greater than its equilibrium solubility.

Stress concentration at the boundary of Ge/Si(100) islands drives strain relief mechanisms activated at higher growth temperature, T. Si interdiffusion for T≥ 550° C forms a reduced misfit alloy allowing specific cluster morphologies to exist at sizes greater than those for pure Ge islands. This interdiffusion also affects the pathway for island shape changes. Trenches formed at the island base result from diffusion of the most highly strained material to regions of lower strain and precede dislocation formation for T≥ 600° C .