We validate for the first time the phenomenological phonon confinement model (PCM) of H. Richter, Z. P. Wang, and L. Ley [Solid State Commun. 39, 625 (1981)] for silicon nanostructures on the sub-3 nm length scale. By invoking a PCM that incorporates the measured size distribution, as determined from cross-sectional transmission electron microscopy (X-TEM) images, we are able to accurately replicate the measured Raman line shape, which gives physical meaning to its evolution with high temperature annealing and removes the uncertainty in determining the confining length scale. The ability of our model to explain the presence of a background scattering spectrum implies the existence of a secondary population of extremely small (sub-nm), amorphous silicon nanoclusters which are not visible in the X-TEM images. Furthermore, the inclusion of an additional fitting parameter, which takes into account the observed peak shift, can be explained by a size-dependent interfacial stress that is minimized by the nanocluster/crystal growth. From this we obtain incidental, yet accurate estimates for the silicon surface energy and a Tolman length, d % 0.15 6 0.1 nm using the Laplace-Young relation.

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Ge thin films are grown on Si͑001͒ substrates by molecular-beam epitaxy at 370°C. The low-temperature epitaxial growth is compatible with the back-end thermal budget of current generation complementary metal-oxide-semiconductor technology, which is restricted to less than 450°C. Reflection high-energy electron diffraction shows that single-crystal Ge thin films with smooth surfaces could be achieved below 450°C. Double-axis x-ray /2 scans also show that the epitaxial Ge films are almost fully strain-relaxed. As expected, cross-sectional transmission electron microscopy shows a network of dislocations at the interface. Hydrogen and oxide desorption techniques are proved to be necessary for improving the quality of the Ge films, which is reflected in improved minority carrier diffusion lengths and exceptionally low leakage currents.

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The initial stage of InAs growth on Si (001) substrate was studied via high-resolution transmission electron microscopy analysis. InAs of thickness less than 1 monolayer grown by molecular beam epitaxy was found to form islands at the onset of the growth, i.e., it follows the Volmer–Weber growth mode. By the introduction of 60° and 90° dislocations, the misfit strain was relieved at the early growth stage for island size as small as 10nm. The average distance between the 60° dislocations is approximately 2nm, indicating nearly complete strain relaxation. The shape evolution of individual islands reveals the transition from pyramidal shape with (111) facets for island diameters smaller than 15nm to dome shape for island diameters larger than 20nm.