Self-boundary substances refer to three kinds of semiconductor materials, namely conductive conductor and insulator semiconductor, whose room temperature conductivity is between conductive material and insulating material, and functional materials, which conduct electricity through holes, have room temperature resistivity of 10-5 ~ 107 ohm-m, which increases with the increase of temperature. If the resistivity is changed by several orders of magnitude by doping impurities or irradiating with light or rays, the silicon carbide detector will be made of 1906.

1947 the invention transistor semiconductor material has developed as an independent material field, and the high-tech field of electrical industry lacks material characteristic parameters. Semiconductor materials are extremely sensitive in conductivity and high in purity. Semiconductor materials are called intrinsic semiconductors, and their resistivity is very high. High-purity semiconductor materials are doped with suitable impurities, which reduces the resistivity of the material because the impurity source provides conductive current carrying. Doped semiconductors are called impurity semiconductors, impurity semiconductors are called N-type semiconductors, and valence band hole conduction semiconductors are called P-type semiconductors.

The contact between semiconductors of the same type (forming a PN junction) or the difference in the concentration of electricity (or holes) between semiconductors and metals produces a barrier-like contact at the diffusion contact. Unidirectional conduction semiconductor devices with the same function, such as diodes, triodes and thyristors, are made by unidirectional conduction of PN junction.

Changes in external conditions (heat, light, electricity, magnetism, etc.). ) is insensitive to external semiconductor materials. Manufacture various sensitive elements for information conversion. The characteristic parameters of semiconductor materials, such as band gap width, resistivity, current-carrying mobility and dislocation density of unbalanced current-carrying life, are determined by the electrical state and original configuration of the semiconductor, and reflect the energy resistivity required to excite the free state of the original price of the material. The current-carrying mobility reflects the conductivity of the material, and the non-equilibrium current-carrying lifetime reflects the relaxation characteristics of the current-carrying inside the semiconductor material from the non-equilibrium state to the equilibrium state under the external action (light or electric field). Dislocation crystals can measure the lattice integrity of semiconductor single crystal materials according to the defect dislocation density, while amorphous semiconductor materials have no parameters. The characteristic parameters of semiconductor materials can only reflect the differences between semiconductor materials and their non-semiconductor materials, and more importantly, they can reflect the differences in characteristic values between various semiconductor materials or even the same material.

Types of semiconductor materials

Using semiconductor material element semiconductor compound semiconductor element semiconductor is made of a single element. The main semiconductor materials are silicon, germanium, selenium and other silicon germanium. Compound semiconductor binary system, ternary system and elemental system organic compound semiconductor binary system compound semiconductor III-V (gallium arsenide, gallium phosphide, indium phosphide, etc. ), II-VI group (cadmium sulfide, cadmium selenide, zinc telluride, zinc sulfide, etc. ) and IV-VI (lead sulfide) IV-IV group (silicon carbide) compound ternary compound semiconductors, mainly ternary solid solution gallium aluminum arsenic solid solution, gallium germanium arsenic phosphorus solid solution and other organic compound semiconductors naphthalene, anthracene and polyacrylonitrile are in the research stage.

External amorphous liquid semiconductor materials are different from crystalline semiconductors. The preparation of crystal structure has strict periodic arrangement. The requirements of semiconductor materials are the same as those of semiconductor devices, including single crystal slicing, grinding, polishing, thin films and other semiconductor materials. The requirements of semiconductor materials should be the same as those of processing technology. Purification of semiconductor material preparation technology and thin film epitaxy of single crystal preparation.

All semiconductor materials need to be purified by raw materials, and the purity of 69 is as high as 1 19. Two kinds of purification by changing the group of substances are called physical purification. Purify the compound of the first change of another element, and then purify the compound. Physical purification of original elements, vacuum evaporation, regional purification, crystal pulling purification, etc. Regional refining and purification mainly adopts distillation for electrolysis, complexation, extraction and rectification.

Due to each limitation, several purification processes are used to obtain qualified materials. Most semiconductor devices, single wafers or epitaxial wafers with single wafer substrates are used as bulk semiconductor single crystals. 80% of silicon single crystal is used for melt Czochralski method, and part of germanium single crystal is used for indium antimonide single crystal. The silicon single crystal with a diameter of 300 mm is introduced into a magnetic field for Czochralski method, and a liquid covering agent is added to the surface of the produced high-uniformity silicon single crystal crucible for magnetically controlled crystal pulling. Liquid sealing is used in Czochralski method, and high purity silicon single crystals such as gallium phosphide and indium phosphide are used for decompression and melt-to-melt contact.

Horizontal directional crystallization of germanium-producing single crystals for horizontal zone melting is mainly used to prepare gallium arsenide single crystals, and vertical directional crystallization is used to prepare various production single crystals of cadmium telluride and gallium arsenide, and then all or part of the processes such as crystal orientation, rolling, datum plane, slicing, grinding, chamfering, polishing, etching, cleaning, detection and packaging are carried out. Which is used for providing a corresponding wafer single crystal substrate. Single crystal films are called epitaxial gas phase, liquid phase, solid phase, beam epitaxy and so on.

Chemical vapor epitaxy (CVD) is mainly used in industrial production, and its liquid phase epitaxy of organometallic compounds is the same as chemical vapor deposition and magnetron sputtering, and is used to prepare amorphous, microcrystalline, crystalline thin-film glass, ceramics, metals and other substrates.

The difference between semiconductor insulators is mainly because the energy band width of both insulators is wider than that of semiconductors, that is to say, the valence band load of insulators must be higher than that of semiconductors to jump to the conduction band. Few carriers have enough energy to enter the conduction band at room temperature. Intrinsic semiconductor insulators have similar electrical characteristics. The bandwidth of the semiconductor means that the conductivity of the semiconductor is easier to control and change.

The electrical characteristics of pure semiconductors are permanently changed by implanting impurities. According to the impurity used for doping, the conductivity of the semiconductor material changes, which is closely related to the built-in electric field at the junction of the semiconductor doped with the same polarity impurity and the high concentration semiconductor impurity, thus allowing the semiconductor device to work.

In addition to permanently changing the electrical properties through doping process, semiconductors are also applied to their electric fields to change the characteristics of semiconductor materials. Transistors are suitable for use as circuit elements. Transistors belong to active semiconductor devices, passive semiconductor devices, resistors or capacitors, which are combined to be used as microprocessors for designing various integrated circuit products.

Conductive strips reduce energy and release seeds in the form of light. The basic commercial applications of light emitting diodes and semiconductor lasers are very important. On the contrary, the semiconductor absorbs light, and the photoelectric effect excites electricity to generate electrical signals, that is, the photodetector source is an important component in the field of optical fiber communication or solar cells.

Examples of single element combination of semiconductor energy Compounds of two or more elements of silicon can be found in compound semiconductor gallium (GaAs) or aluminum indium gallium phosphide (AlGaInP) and other alloy semiconductor materials such as silicon germanium (SiGe) or aluminum gallium arsenic (AlGaAs).