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Semiconductor classification and performance
(1) element semiconductor. Element semiconductor refers to the semiconductor composed of a single element, among which the research on silicon and tin is relatively early. It is a solid material with semiconductor characteristics composed of the same elements, which is easily affected by trace impurities and external conditions. At present, only silicon and germanium have good properties and are widely used. Selenium is used in electronic lighting and photoelectric fields. Silicon is widely used in the semiconductor industry, which is mainly affected by silicon dioxide. It can form a mask on the device, improve the stability of the semiconductor device, and facilitate the automatic industrial production.
(2) inorganic composite semiconductor. Inorganic compounds are mainly semiconductor materials composed of a single element, of course, there are also many elements. The main semiconductor properties are group I and V, VI, VII; group II and IV, V, VI, VII; group III and V, VI; group IV and IV, VI; V and VI; VI and VI combination compounds, but affected by the characteristics of the elements and the way of production, they are not Some compounds can meet the requirements of semiconductor materials. These half conductors are mainly used in high-speed devices, and InP transistors are faster than other materials, mainly used in photoelectric integrated circuits and anti nuclear radiation devices. For high conductivity materials, mainly used in LED and other aspects.
(3) organic compound semiconductor. Organic compounds refer to compounds containing carbon bonds in molecules. Organic compounds are perpendicular to carbon bonds, and can form conduction band in the way of superposition. Through chemical addition, they can enter into the energy band, so conductivity can occur, thus forming organic compound semiconductor. Compared with the previous semiconductors, this half conductor has the advantages of low cost, good solubility and easy light processing. It can control the conductivity by controlling the molecules. It has a wide range of applications, mainly used in organic films, organic lighting and so on.
(4) amorphous semiconductor. It is also called amorphous semiconductor or glass semiconductor, which belongs to a kind of semiconductive materials. Like other amorphous materials, amorphous semiconductors are short-range ordered and long-range disordered. It is mainly through changing the relative position of atoms, changing the original periodic arrangement, forming amorphous silicon. Crystalline and amorphous states are mainly different from whether the atomic arrangement has a long program. It is difficult to control the performance of amorphous semiconductors. With the invention of technology, amorphous semiconductors began to be used. This production process is simple, mainly used in engineering, with good effect in light absorption, mainly used in solar cells and LCD.
(5) intrinsic semiconductors: Semiconductors without impurities and lattice defects are called intrinsic semiconductors. At very low temperature, the valence band of semiconductors is full. After being excited by heat, some electrons in the valence band will cross the forbidden band and enter the empty band with high energy. When there are electrons in the empty band, they will become the conduction band. When there is no one electron in the valence band, they will form a positive hole, which is called a hole. Hole conduction is not an actual motion, but an equivalent. When electrons conduct electricity, the holes of equal electric quantity will move in the opposite direction. [3] under the action of external electric field, they generate directional motion and form macroscopic current, which are called electron conduction and hole conduction respectively. This kind of hybrid conductivity is called intrinsic conductivity. The electrons in the conduction band will fall into the hole, and the electron hole pair disappears, which is called recombination. The energy released during recombination becomes electromagnetic radiation (luminescence) or thermal vibration energy (heating) of lattice. At a certain temperature, the generation and recombination of electron hole pairs exist at the same time and reach a dynamic equilibrium. At this time, the semiconductor has a certain carrier density, so it has a certain resistivity. When the temperature increases, more electron hole pairs will be produced, the carrier density increases, and the resistivity decreases. Pure semiconductors without lattice defects have high resistivity and few practical applications.
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