Semiconductor, refers to room temperature conductivity in sulators. Semiconductor in radio, television and temperature on a wide range of applications.
introduction
Semiconductor: resistivity between metal and insulators and have negative resistance between temperature coefficient of the material. Semiconductor room temperature when resistivity in about 10-5 ~ 107 uefa · m, between the temperature rises resistivity index has decreased. Semiconductor materials many, according to chemical composition can be divided into element semiconductor and semiconductor compound two kinds big. Germanium or silicon is the most common elements semiconductor, Ⅲ - including semiconductor compound Ⅴ clan compounds (gaas, phosphating gallium, etc.), Ⅱ - Ⅵ clan compounds (cadmium sulphide, LiuHuaXin etc.), oxide (mn, chromium, iron, copper oxide), and by Ⅲ - Ⅴ clan compounds and Ⅱ - Ⅵ clan compounds composed of interstitial (gallium aluminum arsenic, gallium arsenic phosphorus, etc.). Besides the above-mentioned amorphous semiconductor outside, still amorphous glass semiconductor, organic semiconductor etc.
Intrinsic semiconductors does not contain impurities without lattice defects of semiconductor called intrinsic semiconductors. At extremely low temperatures, semiconductor valence band is filled with (see the band theory), subject to thermal excitation, the valence band part of electronic and cross the forbidden band into higher energy empty, empty belt with existing in the conduction band, electronic later became the lack of an electronic valence band formed after a positively charged open, called hole (figure 1). The conduction band of electrons and valence band of cavitation called electronic - hole on, all can move freely, namely carriers, they influenced by electric fields outside the generating directional movement and the formation of macro current, respectively called electron conductive and cavities conductive. As a result of the produce of electronic - hole formed hybrid conductive called this intrinsicall conductive. The conduction band of electrons will cavitation, electronic - hole to disappear, known as the compound. Compound when the energy released into the electromagnetic radiation (shine) or the lattice thermal vibration energy (heating). In certain temperatures, electronic - hole to the emergence and compound exist simultaneously and achieve the dynamic balance, then semiconductor has certain carriers density, which has certain resistivity. The temperature rises, will produce more of the electronic - hole right, carriers density increases, resistivity reduce. Without the lattice defects resistivity of pure semiconductor larger, actual application much.
