In this work the Si self-interstitial–carbon interaction has been experimentally investigated and modeled. The interactions between self-interstitials, produced by 20-keV silicon implantation, and substitutional carbon in silicon have been studied using a ${\mathrm{Si}}_{1-y}{\mathrm{C}}_y$ layer grown by molecular beam epitaxy (MBE) and interposed between the near-surface self-interstitial source and a deeper B spike used as a marker for the Si-interstitial concentration. The C atoms, all incorporated in substitutional sites and with a C-dose range of $7\times {10}^{12}–4\times {10}^{14}{\mathrm{a}\mathrm{t}\mathrm{o}\mathrm{m}\mathrm{s}/\mathrm{c}\mathrm{m}}^2,$ trap the self-interstitials in such a manner that the ${\mathrm{Si}}_{1-y}{\mathrm{C}}_y$ layer behaves as a filtering membrane for the interstitials flowing towards the bulk and, consequently, strongly reduces the boron-enhanced diffusion. This trapping ability is related to the total C dose in the ${\mathrm{Si}}_{1-y}{\mathrm{C}}_y$ membrane. Substitutional carbon atoms interacting with self-interstitials are shown to trap Si interstitials, to be removed from their substitutional sites, and to precipitate into the C-rich region. After precipitation, C atoms are not able to further trap injected self-interstitials, and the interstitials generated in the surface region can freely pass through the C-rich region and produce B-enhanced diffusion. The atomistic mechanism leading to Si-interstitial trapping has been investigated by developing a simulation code describing the migration of injected interstitials. The simulation takes into account the surface recombination, the interstitial diffusion in our MBE-grown material, and C traps. Since the model calculates the amount of interstitials that actually react with C atoms, by a comparison with the experimental data it is possible to derive quantitative indications of the trapping mechanism. It is shown that one Si interstitial is able to deactivate about two C traps by means of interstitial trapping and C clustering reactions. The reaction causing trapping and deactivation is tentatively described.

Quantum confinement effects in silicon nanowires (SiNWs) are expected when their diameter is less than the size of the free exciton (with a Bohr radius ∼5 nm) in bulk silicon. However, their synthesis represents a considerable technological challenge. The vapor–liquid–solid (VLS) mechanism, mediated by metallic nanoclusters brought to the eutectic liquid state, is most widely used for its simplicity and control on the SiNWs size, shape, orientation, density, and surface smoothness. VLS growth is often performed within high-vacuum physical vapor deposition systems, where the eutectic composition and the pressure conditions define the minimum diameter of the final nanowire usually around 100 nm. In this article, we present and discuss the SiNWs’ growth by the VLS method in a plasma-based chemical vapor deposition system, working in the mTorr pressure range. The purpose is to demonstrate that it is possible to obtain nanostructures with sizes well beyond the observed limit by modulating the deposition parameters, like chamber pressure and plasma power, to find the proper thermodynamic conditions for nucleation. The formation of SiNWs with sub-5 nm diameter is demonstrated.

The growth of thin cubic silicon carbide (3C-SiC) buffer layers in an horizontal hot-wall chemical vapor deposition reactor, through the carbonization of differently oriented Si surfaces, is presented. A qualitative and quantitative study has been performed on statistical parameters related to voids due to the buffer layer growth on the different substrate orientations emphasizing shape, size, and density as a function of the substrate orientation. Variation in the void parameters can be attributed to the atomic packing density related to the substrate orientations, which were (100) Si, (111) Si, and (110) Si in this study. Scanning electron microscopy and transmission electron microscopy were performed to analyze the surface and the crystalline quality of the 3C-SiC films grown and, eventually, an empirical model for the carbonization of Si surfaces formulated. Large platens characterize the 3C-SiC films with shapes related to the orientations of the substrate. These platens derive from the two-dimensional growth of different SiC islands which enlarge during the process due to the continuous reaction between Si and C atoms. The interior part of platens was characterized by the presence of a pure crystalline material with the presence of small tilts affecting some grains in the 3C-SiC layer in order to relief the stress generated with the substrate.