Silicon selenide

Tomaszkiewicz, Susman, Volin, and O Hare in [94TOM/SUS] measured the enthalpy of formation of SiSe2(cr) and thoroughly reviewed the thermodynamic properties of silicon selenides. No new experimental information is available and in general the values reported in [94TOM/SUS] are accepted by the review. Thermodynamic information is available for SiSc2(cr) and SiSe(g). 

The molar ratio of the III compound to the V compound is typically l/lO.t ] To obtain the desired semiconductor properties, dopants are added such as zinc (from diethyl zinc) or magnesium (from bis(cyclopentadienyl) magnesium) for p doping, and silicon (from silane) or selenium (from hydrogen selenide) for n doping. 

The use of (TMSlsSiH with acyl selenides can also yield new C-C bond formation, as shown with the a,/l-unsaturated lactam ester (Reaction 67). The resulting ketone can be envisaged as potentially useful for the synthesis of 2-acylindole alkaloids. Both the effects of H-donating ability and steric hindrance by the silicon hydride are evident. 

A few ATR probes are commercially available. In the near-IR ATR probes are mostly used as easy-to-use sticking probes for liquids and solids. As the aim is primarily to identify a material, not to measure low concentrations, probes with typically one or two reflections (Figure 5-d) are used. In the mid-IR, similar layouts can be found, using e.g. zinc selenide, germanium or silicon crystals as sensing elements. More sensitive and generally better suited for industrial process control DiComp -type probes (Figure 5-e). The actual ATR element is in this case a thin diamond disc supported by a suitably shaped ZnSe crystal. ATR probes of that type are available off the shelf with between one and nine reflections. If more... 

Secondary alkyl selenides are reduced by (TMS)3SiH, as expected in view of the affinity of silyl radicals for selenium-containing substrates (Table 4.3) [40]. Reaction (4.23) shows the phenylseleno group removal from the 2 position of nucleoside [50]. Similarly to 1,3-dithiolanes and 1,3-dithianes, five- and six-membered cyclic selenoacetals can be monoreduced to the corresponding selenides in the presence of (TMS)3SiH [51]. The silicon hydride preferentially approached from the less hindered equatorial position to give transicis ratios of 30/70 and 25/75 for the five-membered (Reaction 4.24) and six-membered cyclic selenoacetals, respectively. 

Boron oxides Germanium selenide Silicon carbide ... 

A number of companies are currently involved in thin-fllm photovoltaics [17], and low-cost multilayer thin-fllm amorphous silicon and CdTe (cadmium telluride) systems have already been installed in large numbers with efficiencies of the order of 10% and of about 80% output after 25 years of operation. Large-scale plants have been announced for the so-called CIS (cadmium indium selenide) and CGIS (copper gallium indium diselenide), technologies with production efficiencies in the range 12-13% and laboratory measurements up to 19.9% [18]. 

Consequently, the bond is fully saturated for A sp = 0 with a bond order of 1, but it is only partially saturated by the time the gap closes for AEap/2 h = 1 (cf eqn (7.92)) when the bond order equals 0.76. This simple second moment model has been extended to include the compound semiconductors. The resultant values of the bond order are given in Table 7.2. We see that the bonds in tetrahedral carbon and silicon are almost fully saturated, but those in zinc selenide and cadmium telluride are only about 75% saturated due partly to the mismatch in the sp orbitals between chemically distinct atoms. 

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