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.

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The relationships among the equivalent oxide thickness (EOT), nanochemistry, and nanostructure of atomic layer chemical-vapor-deposited (ALCVD) Hf–O-based films, with oxide and nitrided oxide interlayers on Si substrates, were studied using x-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) in annular dark-field imaging (ADF), and parallel electron energy-loss spectroscopy (PEELS), capacitance–voltage, and leakage-current–voltage measurements. The XPS (Hf 4f binding energy shift) studies indicated the formation of Hf–O–Si bonds in as-deposited amorphous films, the amount of which was influenced by the interlayer composition and annealing conditions. After post-deposition annealing in N2 and O2, the Hf–O layers were nanocrystalline. Although HRTEM images showed a structurally sharp interface between the Hf–O layer and the interlayer, angle-resolved XPS, ADF imaging, and PEELS in the STEM revealed a chemically diffused HfSiOx region in between. This interdiffusion was observed by the detection of Si (using Si L edge) and Hf (using Hf O2,3 edge) in the Hf–O layer and the interlayer. For an annealed Hf–O/interlayer stack, with an ALCVD target thickness of 4.0 nm for the Hf–O layer on 1.2 nm of nitrided chemical oxide, the experimentally measured EOT and leakage current (at −1 V) were 1.52 nm and ∼10−8 A/cm2. A three-layer (1.2 nm interlayer of nitrided chemical oxide/compositionally graded, 2 nm region of HfSiOx/2 nm HfO2 layer) capacitor model was used to determine the respective contributions to the measured EOT, and the dielectric permittivity of the interlayer was found to be 6.06. These studies clearly indicate that a total EOT of 1 nm and below is attainable in the Hf–N–O–Si/Si–N–O system.

The dependence of substitutional C fraction on growth temperature and substrate orientation is measured for Si1−yCy alloy films grown on (001) and (118) Si by molecular-beam epitaxy. Secondary ion mass spectrometry and high-resolution x-ray diffraction were used to measure the total C and the substitutional C concentrations, respectively, in several samples prepared at temperatures between 450 and 650 °C. The substitutional C fraction decreased rapidly with increasing temperature in this range, regardless of orientation, and was slightly lower for growth on (118) Si. Cross-sectional transmission electron microscopy on (118)-oriented samples revealed a tendency for C to concentrate periodically on (001) facets which formed immediately after initiation of Si1−yCy growth. A kinetic Monte Carlo simulation based upon enhanced diffusion of Si dimers in the presence of subsurface C predicted a step instability leading to step bunching and the formation of periodic surface features, as well as the accumulation of high C concentrations on nearly (001) planes.