SiOx

SiOx powder have been found to be very different by Ramesh and Rao (1994), SiOx (x=1.7) gives rise to Si2N20, whereas the mixture of Si and Si02 gives rise to a-Si3N4. 

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Figure 17.6 (A) Temporal evolution of photoluminescence and UV spectra (B) of CdSe quantum dots dispersed in CHCI3 [29], (C) The evolution curves of the photoluminescence peak intensity of quantum dot films on four kinds of SiOx substrates [34], Reprinted with permission from references [29] (A) and [34] (B) copyright [2003], American Chemical Society and copyright [2006], American Institute of Physics.

Figure 3.15. (a) Cross-sectional SEM of a spin-coated KSb5Se8 film, prepared using a 0.12M precursor solution (in hydrazine) with 5000rpm spin speed and deposited on silicon coated with -lOOnm of thermal SiOx. (b) Similarly prepared KSb5S8 film, subsequently heated to 475 °C for 2 min on a hot plate and cooled to room temperature. 

TABLE 5.2. Baking Conditions and Colors of Resulting SiOx Films for Samples 1-3... 

This scanned mercury electrode technique is not a conventional measurement approach. We have compared Hg as a top electrode to other thin-film counterelectrodes, particularly platinum and aluminum, using known dielectric materials including a-SiOx, a-TaO and a-Al203 thin films. Current-voltage curves measured using mercury top electrodes are comparable to those measured using Pt or A1 top electrodes. 

In order to overcome these problems, hybridization of both materials (C and Si) in one electrode material by HTC seemed to be a promising option [75]. For this purpose, pre-formed silicon nanoparticles were dispersed into a dilute solution of glucose followed by hydrothermal treatment at 180 °C. The carbon-coated particles were then further treated at 750 °C in order to improve the conductivity and structural order of the carbon layer. It was shown that the hydrothermal treatment, following by high temperature carbonization, resulted in formation of a few nanometer thin layer of SiOx layer on the Si nanoparticles, effectively leading to a Si/SiOx/C nanocomposite. Some TEM micrographs of these materials are shown in Fig. 7.8. 

The lithium-storage properties of these Si SiOx/C nanocomposite electrodes were investigated in different electrolyte systems and compared to pure Si nanoparticles. From all the analyzed systems, the Si SiOx-C nanocomposite in conjunction with the solvent vinylene carbonate (VC) to form the solid-electrolyte interface showed the best lithium storage performance in terms of a highly reversible lithium-storage capacity (1100 mAh g-1), excellent cycling performance, and high rate capability (Fig. 7.9). 

Fig. 7.8 TEM images of the Si SiOx/C nanocomposite nanoparticles produced by hydrothermal carbonization of glucose and Si and further carbonization at 750 °C under N2. (a) Overview of the Si SiOx/C nanocomposites and a TEM image at higher magnification (in the inset) showing uniform spherical particles (b) HRTEM image clearly showing the core/shell structure (c), (d) HRTEM image displaying details of the silicon nanoparticles coated with SiOxand carbon.

Figure 3.18 (a) Scheme of the individual SWNT electrode device. SWNTs are grown on Si/Si02 wafers and contacted byTi leads. A layer of SiOx and PMMA is used as an insulating layer, in which windows are opened to selectively expose the SWNTs. (b) AFM-image of the SWNT in the PMMA window, (c) Low-current measurement setup. The SWNT is exposed to a solution containing a redox-active species, (d) Sampled... 

Block Copolymers Grafted from SiOx and Au Surfaces. 124... 

By also using the LASIP procedure, grafted PS-b-PI and PBd-b-PS block copolymers have been prepared (Fig. 7) [72]. Using silane and thiol-DPE initiators, polymerization was carried out on the SiOx and Au surface by sequential addition of monomers. Typically, after allowing this first reaction to reach completion, the second monomer was added to the living anion, and polymerization of the second block was allowed to proceed. The polymerization was also investigated by SPS [80], AFM, ellipsometry, FT-IR, and XPS. The schematic diagram for the reaction on Au surfaces and the formation of the block copolymers is shown in Fig. 6. The results are summarized in Table 2. 

Ubara, H., Imura, T. and Hiraki, A. Formation of Si-H bonds on the surface of microcrystalline silicon covered with SiOx by HF treatment. Solid State Communications 50, 673 (1984). 

Draw structures of (SiQi)4 IShOjJ. [SiOx U- (StiOn 1 ISLjOtn I,.. and [SiO- . Enclose the repeating units in brackets and show that these empirical formulas are cor rect. How do the ratios of oxygen to silicon correlate with the degree of polymerization m silicates (i.e., discrete ions compared to chains compared to double chains compared to infinite sheets compared to three-dimensional frameworks) ... 

Likewise, irradiation of an n-Si electrode in an aqueous electrolyte efficiently forms an insulating SiOx interface [3]. Reductive decomposition of semiconductors is rarely observed, although it has been claimed that certain p-type III-V semiconductors in the phosphide family decompose to form PH3. 

ESCA results of treated polysilicon substrates indicate that the polysilicon surface, like that of the blank single-crystal Si wafer, is covered with a thin layer of SiOz (<20A). For this substrate, surface layer changes are detected by observing the SiOx/Si ratio vs. that of the blank. VTS/HMDS and VTS/6208 treated surfaces have increased SiOx/Si ratios of 6.8-7.0, while the blank exhibits values of 2.5-2.6. Concomitantly, increases also occur in the carbon concentration. The increases in SiOx/Si ratio and carbon content after surface treatment are interpreted as due to the formation of an additional surface layer through the reaction of the organosilanes and surface —SiOH groups. If a thicker layer had resulted, no Si° would have been detected, because it would have been out of the ESCA detection depth therefore, the reactions are restricted primarily to the first few surface layers. 

Since the RSi= units cap the SiOx(OH)j,(OMe)z clusters formed during sol-gel processing of Si(OMe)4, a hydrophobic inner surface is created, and the resulting aerogels are permanently stable against moisture (unmodified silica aerogels are immediately destroyed... 

The interference to the hydrogen detection of C-I-S structures caused by varying amounts of water vapor is also summarized in Table II. As seen in that table, high concentrations of H2O vapor lower the sensitivity of Pd/SiOx/Si diodes whereas water vapor, in general, lowers the sensitivity of Pd/TiOx/Si diodes at room temperature. 

The effect of elevated operating temperatures on the interference to hydrogen detection arising from O2 for Pd/SiOx/Si diodes is also seen in Table III as a function of H2 ppm levels. As may be noted from this table, the reduced sensitivity to hydrogen, especially at low concentrations, caused by the interference from oxygen is not significant at elevated device operating temperatures i.e., temperature effects dominate. 

Figure 7. Device kinetic response to 160 PPM H2 in wet air (saturated with water vapor) ambient and in dry air ambient at RT. Device used here is a Pd/SiOx (MS X)/n-Si diode and wet air and dry air are initial ambients, respectively.

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