Semiconductor

Semiconductor refers to room temperature conductivity between conductor and insulator ( conductor ) ( insulator ) between the material. In radio, television and the semiconductor temperature measurement has a wide range of applications.

Semiconductor: resistivity is between metals and insulators and has a negative temperature coefficient of resistance material. Room temperature resistivity of about 10-5 ~ 107 o m, elevated temperature resistivity index decreases. Semiconductor materials, according to the chemical composition can be divided into elemental semiconductors and semiconductor compounds two categories. Germanium and silicon is the most common element semiconductor; compound semiconductor including III-V compound ( gallium arsenide, gallium phosphide etc.), II-VI compound ( cadmium sulfide, zinc sulfide and oxide ( ), manganese, chromium, iron, copper oxides), as well as by the III-V and II-VI compounds compounds and compositions of the solid solution ( gallium aluminum arsenide, gallium arsenic phosphide etc.). In addition to the amorphous semiconductor, and amorphous glass semiconductor, organic semiconductor.

Intrinsic semiconductors: free of impurities and defects in semiconductor called intrinsic semiconductor. At very low temperatures, the valence band is filled with a semiconductor (see energy band theory ), subjected to thermal excitation, the valence band portion across the gap into the high energy electron empty, empty exists in electronic into the conduction band, the valence band lacks an electron to form a positive space, called as the hole ( Figure 1 ). Electrons in the conduction band and the holes in the valence band called the electron-hole pairs, can move freely, i.e. carrier, they are under an external electric field generating directional movement and the formation of macroscopic currents, respectively called conduction electron and hole conduction. The electron-hole pairs have formed the mixed type conductive called intrinsic conducting. Electrons in the conduction band will fall into the hole, the electron-hole pairs disappear, known as the compound. Composite energy released into electromagnetic radiation ( light ) or lattice thermal vibrational energy ( heat ). At a certain temperature, electron hole pair generation and composite exist at the same time and attain the dynamic balance, the semiconductor has the certain carrier density, which has a resistivity. When the temperature rises, will produce more electron-hole pairs, carrier density increased, reduced resistivity. No defects of pure resistivity of semiconductor is larger, the practical application is not much.

Diversity

Matter exists in a variety of forms, solid, liquid, gas, plasma and so on. We usually put the electrical conductivity and the thermal conductivity is poor or good material, such as diamond, artificial crystal, amber, ceramics and so on, are called insulators. The conductive, thermal conductivity are relatively good metal such as gold, silver, copper, iron, tin, aluminum and other known as conductor. You can simply put somewhere between a conductor and an insulator material called a semiconductor. Compared with a conductor and an insulator, semiconductor material is found to be the most nights, until the nineteen thirties, when the material purification technology improved, semiconductor truly by the academic recognition.

Classification

Semiconductor classification, in accordance with its manufacturing technology can be divided into: integrated circuit devices, separation devices, optoelectronic semiconductor, logic, analog IC IC, storage and other categories, in general these will be divided into small class. In addition to the application domain, the design method of classification, although not common, but according to IC, LSI, VLSI ( super LSI ) and scale classification method. In addition, there are in accordance with its handling of the signal, can be divided into analog, digital, analog digital hybrid and functional classification method.