Elements semiconducting properties

Trigonal, metallic selenium has been investigated as photoelectrode for solar energy conversion, due to its semiconducting properties. The photoelectrochemistry of the element has been studied in some detail by Gissler [35], A photodecomposition reaction of Se into hydrogen selenide was observed in acidic solutions. Only redox couples with a relatively anodic standard potential could prevent dissolution of Se crystal. 

Polysilanes can be regarded as one-dimensional analogues to elemental silicon, on which nearly all of modern electronics is based. They have enormous potential for technological uses [1-3]. Nonlinear optical and semiconductive properties, such as high hole mobility, photoconductivity, and electrical conductivity, have been investigated in some detail. However, their most important commercial use, at present, is as precursors to silicon carbide ceramics, an application which takes no advantage of their electronic properties. 

Physical Properties. Zinc oxide is a fine white powder that turns yellow when heated above 300 °C. It absorbs UV light at wavelengths below 366 nm. Traces of monovalent or trivalent elements introduced into the crystal lattice impart semiconducting properties. The elementary particles of ZnO obtained by the thermal method may be granular or nodular (0.1-5 pm) or acicular (needle-shaped). Some physical properties are given below ... 

The theory outlined above was developed for group IY semiconducting elements such as silicon and germanium some of the compounds of group III and Y elements, the III-V compounds, are also covalently bonded and have similar electrical properties which can be described in terms of a band model. The best known semiconducting III-V compound is GaAs, which is exploited for both its photonic and semiconducting properties. 

Similarly, the covalent compound ZnS (zinc blende) is a semiconductor that has a structure similar to diamond, where the Zn atoms occupy the FCC lattice sites, and the S atoms occupy four of the eight tetrahedral sites of the FCC lattice (see Section 1.2.2). Analogous semiconducting properties are obtained when elements from the IIIA and VA columns of the periodic table are formed, for example, InAs, GaAs, and InP and also in the case when elements from the IIB and VIA columns of the periodic table are created, for instance, ZnTe and ZnSe. 

A metalloid or semimetal is an element with properties that are intermediate between those of metals and nonmetals, such as semiconductivity. They are found between metals and nonmetals in the periodic table (see shaded elements in Figure 1.2). 

Metalloid (or semimetal) An element with properties that are intermediate between those of metals and nonmetals such as semiconductivity. 

For the heavier elements As, Sb, and Bi, further diversity in structure and stoichiometry is found. The ionic bond model becomes less useful as these species may be thought of as intermetallics, possessing metallic luster, and conduction or semiconduction properties. Typical examples include Na3Bi and NaBi, which becomes superconducting at low temperatures (<2.5 K). Further details will be found in the relevant article for each element, As, Sb, and Bi. Zintl anions of these elements are also known. ... 

Last years diluted ternary semiconductors A°B C 2 which may possess magnetic and semiconducting properties at the same time became the issue of great interest due to their potential application in spintronic devices [1-4]. Meanwhile the systematic representation of changes in their properties upon doping with different elements is still to be made. 

Silicon s most familiar use is in the production of microprocessor chips. Computer microprocessor chips are made from thin slices, or wafers, of a pure silicon crystal. The wafers are doped with elements such as boron, phosphorus, and arsenic to confer semiconducting properties on the silicon. A photographic process places patterns for several chips onto one wafer. Gaseous compounds of metals are allowed to diffuse into the open spots in the pattern, and then the pattern is removed. This process is repeated several times to build up complex microdevices on the surface of the wafer. When the wafer is finished and tested, it is cut into individual chips. 

Elemental silicon is used to make silicone polymers. Its semiconducting properties (Section 13-17) are used in transistors and solar cells. 

Metalloids have some chemical and physical properties of metals and other properties of nonmetals. In the periodic table, the metalloids lie along the border between metals and nonmetals. Silicon (Si) is probably the most well-known metalloid. Some metalloids such as silicon, germanium (Ge), and arsenic (As) are semiconductors. A semiconductor is an element that does not conduct electricity as well as a metal, but does conduct slightly better than a nonmetal. The ability of a semiconductor to conduct an electrical current can be increased by adding a small amount of certain other elements. Silicon s semiconducting properties made the computer revolution possible. 

The elements that fall into this category are silicon, germanium, selenium and tellurium. Iodine shows some semiconducting properties, and phosphorus, sulfur and arsenic can each be obtained in a crystalline form that has the properties of a semiconductor, although this is not the most stable form of these elements under normal conditions. 

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