Semi-conductors, Physics

 

Semiconductor is solid material whose electrical conductivity at room temperature lies between conductivity of a conductor and that of an insulator. At high temperatures its conductivity approaches that of a metal, and at low temperatures it acts as insulators. Every material can be classified as a conductor, an insulator, or a semiconductor. These three distinct classes of material arise from a difference in the structure of the allowed electron energy level. In particular every material possesses both valance and a conduction band for electrons and the energy difference between these two bands will determine how easily an electric current will pass through the material. In semiconductor there is a limited movement of electrons, depending upon the crystal structure of the material used. The substances firstly used for semiconductors were the elements Silicon, germanium and gray tin. It was establish that the incorporation of some impurities in them improves their conductive properties. The property either adds free electrons or creates in holes in the crystals structures of the host substances by attracting electrons. Thus there are two kinds of semiconductors: N-type (negative) in which the current carriers are negative and the P-type, in which the positively charged holes move and carry the current. The process of adding this impurity is called doping, the impurities themselves are called do pants. Certain chemical compounds, including Gallium Arsenide, Indium antimonite, and aluminium phosphate are semiconductors.

 

Posted Date: 7/7/2012 8:49:13 AM | Location : United States







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