Preparation of Semiconductors

Other chemical apphcations being studied include the use of microwaves in the petroleum (qv) industry (175), chemical synthesis (176,177), preparation of semiconductor materials (178), and the processing of polymers (179). 

Apart from the manufacture of derivatives, there are only two known uses for phosphine itself, ie, in the preparation of semiconductors and as a fumigant. 

AJ-Vlayl polymers may be used for the preparation of semiconductors (qv). Derivatives of others have biological activity, eg, a derivative of 2-phenyl-1-vinylpyrrole, 2-phen54-l-(proparg54oxyethyl)pyrrole, stimulates motor activity andiacreases excitation, etc (42) (see Vinyl polymers, M-vinyl amides). 

The preparation of semiconductors by thermal decomposition would appear to be impossible because of the high amount of energy required to break all of the metal-carbon bonds before the atomic species could be formed. However, the thermal method is successful because the reaction to form free methyl radicals, which combine to form ethane, lowers the energetic requirements for the formahon of gallium, for example, according to the equation... 

A number of matrices have also been used for the preparation of semiconductor nanoparticles, whereby the particulate material is grown within and subsequently fills the cavities of the host material. These includes zeolites,361 glasses,362 and molecular sieves,363-365 and can be viewed as nanochambers which limit the size to which crystallites can grow. Other synthetic methods include micelles/microemulsions,366-369 sol-gels,370,371 polymers,372-377 and layered solids.378... 

One difficulty with many synthetic preparations of semiconductor NCs that complicates any interpretation of NMR results is the inevitable distribution of sizes (and exact shapes or surface morphologies). Therefore attempts to make semiconductors as a sort of molecular cluster having a well-defined stoichiometry are of interest to learn potentially about size-dependent NMR parameters and other properties. One approach is to confine the semiconductor inside a template, for instance the cuboctahedral cages of the sodalite framework or other zeolite structures, which have been characterized by multinuclear NMR methods [345-347], including the mesoporous channel material MCM-41 [341, 348]. 

Used industrially for preparation of metallic selenides, organoselenium compounds, and preparation of semiconductor materials. 

Uses. Indium finds application in making low melting alloys the eutectic alloy indium-gallium (14.2 at.% In, 21.4 mass% In) melts at 15.3°C. In is used as an additive to solder alloys to improve malleability at low temperature and corrosion resistance it is also used in dental alloys, in the preparation of semiconductors, etc. 

It may finally be mentioned that molecular beam methods have been used for the preparation of semiconductors as GaP and of thin films of higher polyphosphides. 

Several synthetic methods for the preparation of semiconductor nanoparticles have been reported. Colloidal and organometallic routes have probably been identified as the two major methods in use [11-16], although nano dimensional particles have been also synthesized in confined matrices such as zeolites [17], layered solids [18], molecular sieves [19,20], vesicles/micelles [21,22], gels [23,24], and polymers [25]. An ideal synthetic route should produce nanoparticles which are pure, crystalline, reasonably monodisperse and have a surface which is independently derivatized. 

Hirai T, Watanabe T, Komasawa I (2000) Preparation of semiconductor nanoparticle-polymer composites by direct reverse micelle polymerization using polymerizable surfactants. J Phys Chem B 104 8962-8966... 

Molecular beam epitaxy is an important technique for the preparation of semiconductors (III-V compounds). The finesse and sophistication of modern preparative solid... 

Elemental germanium is used primarily in the preparation of semiconductors in which it is combined with phosphorus, arsenic, or antimony to make n-type semiconductors or with gallium to make p-type semiconductors. 

With a few exceptions, polymerizations are strongly exothermic (see Chap. 5, Sect. 1.1). Therefore removal of the heat of polymerization is the main problem affecting the construction of polymerization reactors and the technology of the process. The kinetics of the process also determines the technology, with the stringent requirement of the purity of medium. In chemistry perhaps only the preparation of semiconductors poses higher requirements on the purity of raw materials and on the prevention of contamination than... 

The preparation of semiconductor specimens in research and in device technology usually involves cutting small... 

The Synthesis and Fabrication of Ceramics for Special Application 219 17.3.8. Preparation of Semiconductors 17.3.8.1. Elemental Semiconductors... 

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