Silicon devices elements

Fig. 2. Drop motion and mixing in a Y-channel device. The device was constructed by bonding the silicon heater elements and glass channels. (A) Initiation of movement by heating the left interface of two drops (nl level) at their starting locations in the branches of the Y-channel, (B) the movement in progress, and (C) the combined drop...

There are many elements and alloys that possess the electrical property known as band gap [5] that are useful for semiconductor devices. Silicon became the lynchpin material for device fabrication. It is currently, and will continue to be, the most important material for integrated circuit fabrication. Alloys of group III and V elements are important for optical devices such as lasers, optical detectors, and specialized high-speed circuits. In this paper, the fabrication of silicon devices will be used to illustrate the role of chemical processing in circuit manufacture. 

There are, however, also some drawbacks to these devices. Because of their poor sensitivity, silicon Hall elements provide only a very small output voltage, which must be highly amplified. Their inevitable offset voltage is subject to significant fluctuations because of amplitude and temperature coefficients, and the strong temperature-dependent sensitivity requires adequate compensation. Thus, similarly to the resistive current principle, the amplifying circuit often defines the quality of the sensor. 

The element silicon. Si, plays a decisive role in modern human life, and chlorine chemistry plays a decisive role in silicon chemistry, though chlorine is not a constituent in the applications of silicon and of most silicon compounds. Modern electronics is almost exclusively based on silicon devices, both in low-power and in high-power electronics. Silicon products have captured market share in many applications because of their superior performance [347]. 

Integrated circuits (ICs) are comprised of layers of deposited thin films of metals and dielectrics which form device elements and metal contacts between the elements. The common methods of deposition are physical vapor deposition (PVD) and chemical vapor deposition (CVD). PVD is usually used to deposit metals like aluminum. CVD is often the process for growing oxides and polycrystalline silicon, which is doped to act as a metal electronically. 

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. 

The newest addition to the forms of elemental carbon is the nanotube. A carbon nanotube is a long cylinder of carbon atoms, connected together in much the same way as in a fullerene. Both the diameter and the length of carbon nano-tubes can vary. Properties of nanotubes, such as their ability to conduct electrical charge, change dramatically with the dimensions of the tube. Carbon nanotubes are under intensive study. For example, a carbon nanotube laid down on a silicon chip forms a molecular transistor. Such devices may eventually lead to further miniaturization of the chips that are at the heart of modem computers. 

The relatively large band gaps of silicon and germanium limit their usefulness in electrical devices. Fortunately, adding tiny amounts of other elements that have different numbers of valence electrons alters the conductive properties of these solid elements. When a specific impurity is added deliberately to a pure substance, the resulting material is said to be doped. A doped semiconductor has almost the same band stmeture as the pure material, but it has different electron nonulations in its bands. 

Silicon s atomic structure makes it an extremely important semiconductor. Highly purified silicon, doped with such elements as boron, phosphorus, and arsenic, is the basic material used in computer chips, transistors, sUicon diodes, and various other electronic circuits and electrical-current switching devices. Silicon of lesser purity is used in metallurgy as a reducing agent and as an alloying element in steel, brass, and bronze. 

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