Silicon platelet

Channel carrier a, b Microstructured silicon platelet quartz glass tube Reaction channel a cross-sectional area depth length 0.167 mm 525 pm 20 mm... 

The thickness of the deposited layers was measured by SEM microscopy and profilometry [39]. For both methods silicon platelets were used as substrates. For SEM microscopy, the coated Si platelets were broken and such a cross-section can be obtained. Fig. 14A shows the SEM cross-section of a broken Si sample coated with carbon for 30 min. The silicon substrate is represented by the bright white part on the left of the image, while the gray shadow part represents photo-deposited carbon layer. The dependence of the carbon layer thickness on deposition time measured by SEM and by profilometry is presented in Fig. 14B. Data of both methods show a nearly linear increase of the thickness with the deposition time. 

Colloidal suspensions are systems of small mesoscopic solid particles suspended in an atomic liquid [1,2]. We will use the term colloid a little loosely, in the sense of colloidal particle. The particles may be irregularly or regularly shaped (Fig. 1). Among the regular shapes are tiny spherical balls, but also cylindrical rods or flat platelets. As the particles are solid, fluctuations of their form do not occur as they do in micellar systems. Not all particles in a suspension will, in general, have the same form. This is an intrinsic effect of the mesoscopic physics. Of course in an atomic system, say silicon, all atoms are precisely similar. One is often interested in the con-... 

The nature of the nucleation site as well as the kinetics of formation and dissociation of the H-induced and stabilized platelets have yet to be experimentally studied in detail. However, their generation in float-zone (Johnson and Herring, 1988b) as well as Czochralski-grown (Fig. 8) silicon argues against the involvement of oxygen or carbon in platelet nucleation. 

In addition to the generation of platelets, hydrogenation of silicon also induces electronic deep levels in the band gap. As in the case of platelet formation, these defects are considered to be unrelated to either plasma or radiation damage because they can be introduced with a remote hydrogen plasma. Comparison of depth distributions and annealing kinetics of the platelets and gap states has been used to a limited extent to probe the relationship among these manifestations of H-induced defects. 

Another open question is the relationship between the H-induced radiative recombination centers and the H-induced platelets. Controlled layer removal of the plasma-processed silicon surface reveals that the density of luminescence centers decays nearly exponentially with a decay length that is comparable to the depth over which the platelets form (Northrop and Oehrlein, 1986 Jeng et al., 1988 Johnson et al., 1987a). However, the defect luminescence has also been obtained from reactive-ion etched specimens in which platelets were undetectable (Wu et al., 1988). Finally, substantial changes in the luminescence spectra occur at anneal temperatures as low as 250°C (Singh et al., 1989), while higher temperatures... 

Apart from its role in interacting with existing defects and impurities, hydrogen has recently been shown to induce defects as well (Johnson et al., 1987). Extended defects (described as platelets ) in the near-surface region were observed after hydrogenation and correlated with the presence of large concentrations of H. Theoretical models will be discussed in Part VIII. Part IX, finally, will contain some conclusions and point out directions for future work. As is the case for so many other topics in semiconductor physics, silicon (Si) has been the material for which the majority of... 

Baca, A. J. Meitl, M. A. Ko, H. C. Mack, S. Kim, H.-S. Dong, J. Ferreira, P. M. Rogers, J. A. 2007. Printable single-crystal silicon micro/nanoscale ribbons, platelets and bars generated from bulk wafers. Adv. Fund. Mater. 17 3051-3062. 

Exists in two adotropic modifications. Crystalline sihcon is made up of grayish-black lustrous needle-hke crystals or octahedral platelets cubic structure Amorphous sdicon is a brown powder. Other physical properties are density 2.33g/cm3 at 25°C melts at 1,414°C high purity liquid silicon has density 2.533 g/cm at its melting point vaporizes at 3,265°C vapor pressure 0.76 torr at 2,067°C Mohs hardness 6.5. Brinell hardness 250 poor conductor of electricity dielectiric constant 13 critical temperature 4°C calculated critical pressure 530 atm magnetic susceptibility (containing 0.085%Fe) 0.13x10 insoluble in water dissolves in hydrofluoric acid or a mixture of hydrofluoric and nitric acids soluble in molten alkalies. 

The first crystalline silicon was prepared by Henri Sainte-Claire Deville in 1854 ( 9,31). In the course of his researches on aluminum, he decomposed an impure sodium aluminum chloride with the voltaic pile, and obtained a gray, brittle, granular melt containing 10.3 per cent of silicon. When he dissolved away the aluminum, some shining platelets remained. 

X-ray diffraction techniques can be used to establish the structure of crystalline polymers. Measurements are typically made on crystalline lamellar platelets grown from dilute solution, fibres or stretched films. Such methods have been applied to several different inorganic polymers. For example, based on measurements on stretched samples of silicone rubber, poly(dimethylsiloxane) (Me2SiO) has been shown to possess a helical conformation (Figure 8.4). ... 

For instance, the modification of silicone rubbers, poly-(tetrafluoroethylene), polyethylene, and segmented polyurethanes by ionic attachment of heparin was shown to result in a decrease of platelet adhesion onto these polymers71 74 75. A similar... 

There is further data confirming the results compiled in Table 12. Figure 5 shows the results of the studies on the interaction of heparinized silicone rubber with blood 4). The surface is seen to adhere the platelets up to its complete saturation, which then prevents further interaction. 

Quite significant is the fact that the amount of platelets adhered depends on the synthesis procedure for HCP. For example, the platelet adhesion onto silicone rubbers heparinized via the TDMAC procedure was 150000 platelets/cm2, while the very same rubbers that were heparinized via y-aminopropyltriethoxysilane adhered only 90000 platelets/cm2 88). The platelets are to a greater extent adhered by the polymers containing covalently immobilized heparin than by those that elute heparin into the bloodstream n3) although the immobilized heparin itself does not interact with the platelets 21 . 

Fig. S. Platelet count of blood having been contacted with heparinized silicone rubber as a function of blood volume41...

Johnson and coworkers (Johnson etal., 1986a) found that shallow donor dopants in n-type single-crystal silicon could also be neutralized by hydrogenation, although not as effectively as with boron, Further investigations led Johnson and coworkers (Johnson et al., 1987) to discover the surprising result that H can insert itself between Si—Si bonds to form extended structural defects that may be described as hydrogen-stabilized platelets. 

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