Basic knowledge of semiconductors
2022-11-21
Basic knowledge of semiconductors
A semiconductor is an object with conductivity between that of a conductor and an insulator. The particles carrying charges inside it have electron carriers
Semiconductors are materials that are situated between conductors and insulators, possessing unique electronic conductivity properties. In semiconductors, the band structure of electrons is between the conduction and valence bands, allowing the conductivity of the semiconductor to be adjusted by controlling external conditions.
The basic characteristics of semiconductors include the following aspects:
1. Conductivity:
The conductivity of semiconductors depends on the size of their bandgap. In semiconductors, the electrons in the valence band are almost fully occupied, while the electrons in the conduction band are almost empty. Only when electrons gain sufficient energy can they transition from the valence band to the conduction band, forming an electric current. Therefore, the conductivity of semiconductors is between that of conductors and insulators.
2. P-type and N-type semiconductors:
Doping is a method of altering the conductivity of semiconductors. Doping is the process of adding a small amount of impurities to a pure semiconductor to form a P-type or N-type semiconductor. In P-type semiconductors, impurities doped with excess electrons are called donors; In N-type semiconductors, impurities doped with missing electrons are called acceptors. Doping increases the carrier concentration in semiconductors, thereby enhancing their conductivity.
3. PN junction:
A PN junction is a structure formed by direct contact between P-type and N-type semiconductors. In the PN junction, electrons in the P and N regions are rearranged, forming diffusion currents for positive holes and negative electrons. In the PN junction, the donor in the P region and the acceptor in the N region undergo recombination, forming a recombination current of electrons and positive holes. PN junction has rectification characteristics, and when a forward bias voltage is applied, current easily passes through; When the reverse bias voltage is applied, the current can hardly pass through.
4. Semiconductor devices:
Based on the characteristics of semiconductor materials, various semiconductor devices have been developed. Common semiconductor devices include diodes, transistors, field-effect transistors, integrated circuits, etc. These devices perform functions such as amplification, switching, and storage by controlling the electronic behavior in semiconductor materials.
5.Temperature characteristics:
The conductivity of semiconductors is closely related to temperature. As the temperature increases, lattice vibrations intensify and the number of electrons in the conduction band increases, resulting in enhanced conductivity of the semiconductor. But at high temperatures, semiconductor materials may melt or oxidize, resulting in limited electrical performance.
In short, semiconductors are materials with special conductive properties that are widely used in electronic devices, communication technology, energy industries, and other fields. Through continuous research and development, semiconductor technology has become one of the important supports of modern society.
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