Strained silicon

S. Kal, N. B. Chakrabarti. Strained silicon-SiGe devices using germanium implantation. IETF J Res 45 185, 1997. 

The major synthetic routes to transition metal silyls fall into four main classes (1) salt elimination, (2) the mercurial route, a modification of (1), (3) elimination of a covalent molecule (Hj, HHal, or RjNH), and (4) oxidative addition or elimination. Additionally, (5) there are syntheses from Si—M precursors. Reactions (1), (2), and (4), but not (3), have precedence in C—M chemistry. Insertion reactions of Si(II) species (silylenes) have not yet been used to form Si—M bonds, although work may be stimulated by recent reports of MejSi 147) and FjSi (185). A new development has been the use of a strained silicon heterocycle as starting material (Section II,E,4). 

Strained silicon wafers, in scaling to deep submicron dimensions, 22 256 Strainers, in refrigeration systems, 27 539 Strain fixity rate (R ), in testing shape-memory polymers, 22 361... 

Since strained silicon-silicon a-bonds are mnch more reactive than the linear Si—Si bond toward atmospheric oxygen, most stndies were carried ont for strained disiliranes 82. 

Hayazawa, N., Motohashi, M., Saito, Y, and Kawata, S. 2005. Highly sensitive strain detection in strained silicon by surface enhanced Raman spectroscopy. Appl. Phys. Lett. 86 263114. 

Braunstein and coworkers have shown (vide supra) that in the bimetallic Fe—Pt complex (CO)3(SiR3)Fe(yU.-PPh2)Pt(PPh3)CO(Fe—Pt), a silyl migration occurred from the Fe to the Pt center (Scheme 17)102. Remarkably, the first example of a well-characterized insertion of a transition-metal fragment into a strained silicon-carbon bond of a silicon-bridged [l]ferrocenophane was recently reported by Sheridan, Lough and Manners. The... 

The reaction of methylenecyclopropanes with transition metal complexes is well known to promote a catalytic a-ir cycloaddition reaction with unsaturated compounds, in which a trimethylenemethane complex might exist71-76. Recently, much interest has been focused on the interaction of strained silicon-carbon bonds with transition metal complexes. In particular, the reaction of siliranes with acetylene in the presence of transition metal catalysts was extensively investigated by Seyferth s and Ishikawa s groups77-79. In the course of our studies on alkylidenesilirane, we found that palladium catalyzed reaction of Z-79 and E-79 with unsaturated compounds displayed ring expansion reaction modes that depend on the (Z) and (E) regiochemistry of 79 as well as the... 

In the commercial technology of 2004, the copper wires in Intel s Pentium 4 logic chip are produced in their newest 300 mm wafer fabrication facility in Ireland, and are 90 nm wide [3]. The use of strained silicon [4] is one of several approaches tested to modify present silicon-based processes to meet the demands of the development roadmap. Now, considering a typical molecular wire, investigated in our lab with a width of 0.4 nm and a length of 2.5 nm, see Fig. 2.1. Compared to the Pentium 4 chip 300 of such molecules, side-by-side, would span the 90 nm metal line. 

Both PFS-PI and PFS-PDMS are synthesized by two-step anionic polymerization. The synthetic approach for the preparation of PFS-PDMS is shown in Scheme 1 [8,9] n-butyllithium was used to initiate the polymerization of the strained silicon-bridged ferrocenophane in THF solution, while the second block was built by the subsequent addition of hexamethyltrisiloxane (D3). The reaction was terminated with chlorotrimethylsilane. To obtain PFS-PI, the PI block was initiated with butyllithium, followed by the addition of the silicon-bridged ferrocenophane. 

The strained silicon-carbon bonds of silacyclobutanes are subject to activation by Pd and Pt complexes. This reactivity has been used for a catalytic carbon-carbon bond formation.294,295... 

Figure 4.21. Formation of strained silicon from the epitaxial growth of lattice mismatched Si onto a SiGe substrate.

Fig. 16.8 Reflection TERS image (800 x 800 nm ) of strained silicon. Image is plotted as a Raman shift (not Raman intensity) at each pixel. Excitation wavelength Is 442 nm. The tip is a silver-coated SI3N4 cantilever...

Tarun A, Hayazawa N, Motohashi M, Kawata S (2008) Highly efficient tip-enhanced Raman spectroscopy and microscopy of strained silicon. Rev Sci Instrum 79 013706 PalikED (ed) (1991) Handbook of optical constants of solids. Academic, Orlando Taguchi A, Hayazawa N, Furusawa K, Ishitobi H, Kawata S (2009) Deep-UV tip-enhanced Raman scattering. J Raman Spectrosc 40 1324... 

Saito Y, Motohashi M, Hayazawa N, lyoki M, Kawata S (2006) Nanoscale characterization of strained silicon by tip-enhanced Raman spectroscope in reflection mode. Appl Phys Lett... 

Moutanabbir O, Reiche M, Hahnel A, Erfurth W, Motohashi M, Tarun A, Hayazawa N, Kawata S (2010) UV-Raman imaging of the in-plane strain in single ultrathin strained silicon-on-insulator patterned structure. Appl Phys Lett 96 233105... 

We next present the BTE and MD predictions of thermal conductivities of silicon thin films. The thermal properties of silicon thin films are of paramount importance to the transistor industry. Silicon-on-insulator (SOI) and strained silicon transistors are composed of silicon thin films. In both cases, the thin silicon film is deposited on top of poor thermally conducting materials, and the thermal energy generated by the Joule effect has to be removed along the silicon film plane. A thorough understanding of the thermal properties of thin silicon films is essential for the accurate prediction of the thermal response of these transistors. The dimensions of the silicon thin film in... 

SOI and strained silicon transistors are comparable to or smaller than the phonon s mean free path (which, for silicon, has been estimated as 300 nm at 300K) [53], In this limit, the film surfaces alter the phonon dispersion relations [76], and the phonon-surface scattering may become the predominant scattering mechanism [3, 53], Since phonons are the main carriers of thermal energy in silicon, these effects alter the thermal conductivity, which differs from that of bulk silicon [10, 36, 77], Measurements of the thermal conductivities of silicon films of thicknesses down to 74 nm found a reduction of 50% with respect to the bulk value at 300K [53], This reduction depends on the temperature and the thickness of the film [3, 53],... 

All studies mentioned in this section have been single-wavelength/single-frequency maps, and thus restricted to the imaging of changes in band intensities, such as the Si phonon band of strained silicon. Important information that can... 

The spectra of samples with layers which contain strained silicon bonds - Ge/Si quantum dots and Si Er - are characterized by the developed fine structure in the energy range of 101 - 104 eV. Nobody has ever observed such fine structure up to now. Conesponding energy levels in the conduction bands can participate in the luminescence spectra. The most striking thing here is a close similarity of the Ge/Si spectra and Si Er samples. Nevertheless, one should remember that surfaces of practically all nanostmctures were capped with thin protecting epitaxial layer of... 

Disilane 285 with PTAD has been shown to provide 286, a product of urazole insertion into the strained silicon-silicon a bond (91JA6286). 

Living anionic ROP of strained silicon-bridged [l]ferrocenophanes (Section 3.3.3) provides an excellent route to PFS block copolymers with controlled block lengths and narrow polydispersities (PDI<1.1) [82-84]. Diblock, triblock, and more complex architectures are now known for a wide variety of organic, inorganic, or even other polyferrocene coblocks. The prototypical materials prepared in the mid-1990s were the diblock copolymers polyferrocenylsUane-h-polydimethylsiloxane (PFS-fo-PDMS) 3.52 and polystyrene-b-polyferrocenylsUane (PS-i -PFS) 3.54 83j. As shown in Scheme 3.4, initial anionic polymerization of monomer 3.21... 

The situation for strained silicon-containing ring compounds has become if anything, more confusing since the previous review. The only new experimental data, are those for a series of siletanes " (silacyclobutanes), shown in Table 8. From these, strain enthalpies in the range of 109-120 kJmol can be calculated. These are slightly larger than an... 

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