Semiconductors

Matter exists in various forms, solids, liquids, gases, plasma, and so on. We usually refer to materials with poor electrical conductivity, such as coal, intraocular crystals, amber, ceramics, etc., as insulators. Metals with good conductivity, such as gold, silver, copper, iron, tin, aluminum, etc., are called conductors. The material between a conductor and an insulator can simply be called a semiconductor. Compared with conductors and insulators, the discovery of semiconductor materials was the latest, and it was not until the 30s of the 20th century, when the purification technology of materials was improved, that the existence of semiconductors was truly recognized by the academic community.

 

 

Discovered

In 1833, Faraday, the father of electronics, a British scientist, was the first to discover that the resistance of silver sulfide is different from that of ordinary metals with temperature, and in general, the resistance of metals increases with the increase of temperature, but Faraday found that the resistance of silver sulfide materials decreases with the increase of temperature. This is the first discovery of the semiconductor phenomenon

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Classification & Performance

 

Elemental semiconductors. Elemental semiconductors refer to semiconductors composed of a single element, among which silicon and selenium have been studied earlier. It is a solid material with semiconductor properties composed of the same elements, which is susceptible to changes due to trace impurities and external conditions. At present, only silicon and germanium have good performance and are widely used, and selenium is used in the field of electronic lighting and opto-electronics. Silicon is used in the semiconductor industry, which is mainly affected by silica, which can form a mask on the device fabrication, which can improve the stability of semiconductor devices and is conducive to automated industrial production. 0020-34694 LINER, GDP, R2 OXIDEGECO, 0020-34695 LINER, CATHODE, FULL FLOW, OXIDE, 0040-09001Chamber Body, Standard 4-6", 0040-09723 -Unibody, Etch Chamber, 0040-02544 Upper Body, DPS Metal, 0040-04745 Chamber Body Ultima Hdp-cvd, 16-033932-00 6 inch showhead WELD,0010-00889 ASSY LIFTER DEGAS/ ORIENTER w/ TC are all used in elemental semiconductors area.

 

Inorganic synthetic semiconductors.

Inorganic compositions are mainly composed of semiconductor materials by a single element, of course, there are also semiconductor materials composed of a variety of elements, the main semiconductor properties are group I and V, VI, VII, II and IV, V, VI, III and V, VI, IV and IV, VI groups; V and VI groups, VI and VI group binding compounds, but affected by the characteristics of the element and the way it is made, not all compounds can meet the requirements of semiconductor materials. This semiconductor is mainly used in high-speed devices, and the transistors manufactured by InP have higher speed than other materials, and are mainly used in optoelectronic integrated circuits and anti-nuclear radiation devices. For materials with high conductivity, they are mainly used in LEDs and other aspects.

 

Organic synthetic semiconductors. Organic compounds refer to compounds containing carbon bonds in the molecule, and the organic compounds and carbon bonds are perpendicular to each other, and the superposition can form conduction bands, which can enter the energy bands through chemical addition, so that conductivity can occur, thus forming organic compound semiconductors. Compared to conventional semiconductors, this semiconductor has the characteristics of low cost, good solubility, and easy processing of materials. The conductivity can be controlled by controlling molecules, and the application range is relatively wide, mainly used in organic films, organic lighting, etc.

 

 

Amorphous semiconductors. I

t is also called amorphous semiconductor or glass semiconductor, which belongs to a class of semi-conductive materials. Amorphous semiconductors, like other amorphous materials, are short-range ordered and long-range disordered structures. It mainly forms amorphous silicon by changing the relative position of atoms and changing the original periodic arrangement. The crystalline and amorphous states are mainly distinguished by whether the arrangement of atoms has a long program or not. The performance of amorphous semiconductors is difficult to control, and with the invention of technology, amorphous semiconductors began to be used. This manufacturing process is simple, mainly used in engineering, has a good effect in light absorption, and is mainly used in solar cells and liquid crystal displays.

 

 

Intrinsic semiconductors: Semiconductors that do not contain impurities and have no lattice defects are called intrinsic semiconductors. At very low temperatures, the valence band of the semiconductor is a full band, after being thermally excited, some electrons in the valence band will cross the forbidden band into the empty band with higher energy, and the presence of electrons in the valence band becomes a conduction band, and the lack of an electron in the valence band forms a positively charged vacancy, called a hole. Hole conduction is not an actual motion, but an equivalence. When electrons conduct electricity, the holes of equal charge move in their opposite direction. They produce directional motion under the action of an external electric field to form macroscopic currents, which are called electron conduction and hole conduction, respectively. This hybrid conduction, which is formed due to the generation of electron-hole pairs, is called intrinsic conductivity. The electrons in the conduction band fall into the holes, and the electron-hole pairs disappear, which is called recombination. The energy released during recombination becomes electromagnetic radiation (luminescence) or thermal vibration energy (heat generation) of the crystal lattice. At a certain temperature, the generation and recombination of electron-hole pairs exist simultaneously and reach dynamic equilibrium, at which point the semiconductor has a certain carrier density and thus a certain resistivity. As the temperature increases, more electron-hole pairs will be generated, the carrier density will increase, and the resistivity will decrease. Pure semiconductors without lattice defects have a large resistivity and are not widely used in practice.

 

 

Applied Fields

 

Semiconductors are used in integrated circuits, consumer electronics, communication systems, photovoltaic power generation, lighting applications, high-power power conversion and other fields.

 

Photovoltaic applications

 

The photo generated volt effect of semiconductor materials is the basic principle of the operation of solar cells. At this stage, the photovoltaic application of semiconductor materials has become a hot topic, and it is currently the fastest growing and best-developed clean energy market in the world. The main material of solar cells is semiconductor materials, and the main criterion for judging the advantages and disadvantages of solar cells is the photoelectric conversion rate, the higher the photoelectric conversion rate, the higher the working efficiency of the solar cell. Depending on the semiconductor material used, solar cells are divided into crystalline silicon solar cells, thin-film cells, and III-V compound cells.

 

 

Lighting Applications

 

LED is a semiconductor light-emitting diode built on a semiconductor transistor, using LED technology semiconductor light source is small in size, can achieve planar packaging, low heat value when working, energy saving and high efficiency, long product life, fast response speed, and green environmental protection without pollution, but also can be developed into thin and short products, once it came out, it has quickly popularized, become a new generation of high-quality lighting source, has been widely used in our lives. Such as traffic lights, backlights for electronic products, urban night landscaping light sources, indoor lighting and other fields, there are applications.