The elastic constants c 11 and c 44 of single-crystal NaCl-structure ␦-TiN x ͑001͒ layers, with x ranging from 0.67 to 1.0, were determined using sound velocity measurements. Picosecond ultrasonic optical pump/probe techniques were employed to generate and detect longitudinal sound waves and surface acoustic waves ͑SAW͒ in order to obtain c 11 ͑x͒ and c 44 ͑x͒, respectively. SAW generation was achieved by depositing a periodic series of Al bars on the TiN x ͑001͒ layers to spatially modulate the surface reflectivity. c 11 and c 44 were found to decrease continuously from 626 and 156 GPa with x = 1 to 439 and 92 GPa with x = 0.67. The Voit-Reuss-Hill average aggregate elastic moduli E VRH ͑x͒ obtained from our measured c 11 ͑x͒ and c 44 ͑x͒ values are in good agreement with previous TiN x ͑001͒ nanoindentation results.

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The effects of lanthanum incorporation into HfO2 dielectrics were studied using first-principles total energy calculations. The author’s computational result clearly showed that the formation energy of a neutral oxygen vacancy (VO0) in the vicinity of substitutional La atoms at Hf sites is 0.7eV larger than that in pure HfO2, indicating that the concentration of VO0’s is drastically reduced by La incorporation. This effect is understood to be caused by the decrease in the local dielectric constant κL around La atoms due to the strong ionic character of the La–O bond compared to the Hf–O bond.

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Ge/Si͑001͒ layers are grown by gas-source molecular beam epitaxy at 600°C to probe island self-ordering phenomena. We vary the Ge growth rate by a factor of 40, 1.2-47 monolayers ͑ML͒ min Ϫ1 , and adjust the Ge coverage, 5.9-8.9 ML, to produce films consisting primarily of dome-shaped Ge islands. Measurements of the radial and nearest-neighbor distributions are compared to calculated distributions for random arrangements of circular islands. At low growth rates, island formation is inhibited at small separation. At high growth rates, the angular distributions of nearest-neighbor islands show pronounced island ordering along ͗100͘ directions.

A comparison is made between 'Born' and 'binary-encounter' generalized oscillator strengths of the continuum states of hydrogen for hydrogen atom impact. The results of this comparison show that resonance excitations are less important for ionization by hydrogen atom impact than for ionization by proton impact and that, consequently, the Born and binary-encounter approximations will be in closer agreement in the former case than in the latter case.

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Dislocations are line defects that bound plastically deformed regions in crystalline solids. Dislocations terminating on the surface of materials can strongly influence nanostructural and interfacial stability, mechanical properties, chemical reactions, transport phenomena, and other surface processes. While most theoretical and experimental studies have focused on dislocation motion in bulk solids under applied stress and step formation due to dislocations at surfaces during crystal growth, very little is known about the effects of dislocations on surface dynamics and morphological evolution. Here we investigate the near-equilibrium dynamics of surface-terminated dislocations using low-energy electron microscopy. We observe, in real time, the thermally driven nucleation and shape-preserving growth of spiral steps rotating at constant temperature-dependent angular velocities around cores of dislocations terminating on the (111) surface of TiN in the absence of applied external stress or net mass change. We attribute this phenomenon to point-defect migration from the bulk to the surface along dislocation lines. Our results demonstrate that dislocation-mediated surface roughening can occur even in the absence of deposition or evaporation, and provide fundamental insights into mechanisms controlling nanostructural stability.