Silicon hyperpure

Silicon is prepared commercially by heating silica and carbon in an electric furnace, using carbon electrodes. Several other methods can be used for preparing the element. Amorphous silicon can be prepared as a brown powder, which can be easily melted or vaporized. The Gzochralski process is commonly used to produce single crystals of silicon used for solid-state or semiconductor devices. Hyperpure silicon can be prepared by the thermal decomposition of ultra-pure trichlorosilane in a hydrogen atmosphere, and by a vacuum float zone process. 

Hyperpure silicon can be doped with boron, gallium, phosphorus, or arsenic to produce silicon for use in transistors, solar cells, rectifiers, and other solid-state devices which are used extensively in the electronics and space-age industries. 

Regular grade silicon (99%) costs about 0.50/g. Silicon 99.9% pure costs about 50/lb hyperpure silicon may cost as much as 100/oz. 

Trichlorosilane (TCS) is the basic material for the production of hyperpure silicon for the semiconductor industry according to the Siemens process. It is produced by hydrochlorination of technical-grade silicon Si + 3HC1 SiHCls + H2 [1 - 5]. The process aims at maximizing the selectivity toward the main product TCS and at minimizing the by-products like silicon tetrachloride (STC), dichlorosilane (DCS) and the so-called high boilers. Despite decades of industrial practice, the hydrochlorination of silicon is poorly understood. 

Many applications of silicon require a very pure product. Methods have been developed to produce silicon that is at least 99.97 percent pure silicon. This form of silicon is called hyperpure silicon. 

Perhaps the best known use of silicon is in electronic devices. Hyperpure silicon is used in transistors and other components of electronic devices. It is also used to make photovoltaic (solar) cells, rectifiers, and parts for computer circuits. A photovoltaic cell is a device that converts sunlight into electrical energy. A rectifier is an electrical device for changing one... 

Grade Ferrosilicon, regular (97% silicon), semiconductor or hyperpure (99.97% silicon), amorphous. 

A p-type material is one with positive holes and an n-type material is one with electrons in excess. To create these types of matrices, small amounts of impurities are incorporated into some host materials. For example, if the host material is silicon, which has four valence electrons, it may be doped with boron, which has three valence electrons. This creates regions in the matrix where there are holes for electrons to occupy it becomes a p-type material. The energy for creating an electron-hole pair is 3.7 eV in silicon and 3.0 eV in germanium (Knoll 1989). Thin wafers of silicon diode surface barrier detectors that have a very thin layer of gold on the surface are used for alpha-particle spectroscopy. Hyperpure germanium detectors, typically a closed-end coaxial, 6 cm in... 

The detectors used in the various forms of EDXRF are semiconductor detectors Conventionally, two types, i. e. lithium drifted silicon (Si(Li)) and hyperpure germa nium (HP-Ge) detectors are used. Their main advantages are their compact size the non-moving system components, and relatively good energy resolution which optimally is of the order of 120 eV at 5.9 keV. Because of their operation prin... 

The technology of silicon deals mainly with the big scale production of hyperpure silicon, silicon carbide, silicates and silica, and industrial silicone products. The surface synthesis and modification of a wide range of substrates may be accomplished with silanes. Deposition techniques include the... 

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