With the development of science and technology and the progress of mankind, electronic technology has become the core of various engineering technologies, especially since entering the information age, electronic technology has become a basic technology, and its specific application fields cover communication fields, control systems, test systems, computers and other industries.
With the appearance and application of electronic technology, mankind has entered the high-tech era. Although the history of the birth of electronic technology is short, its in-depth field is the widest and deepest, and it has become the material technology and foundation for human beings to explore the macro-optical world and the micro-world. Electronic technology is developed by human beings in production struggle and scientific experiments. 1883, American inventor Edison discovered the hot electron effect, and then in 1904, Fleming made an electronic diode by using this effect, and confirmed that the electron tube had the function of "valve" and was used for radio detection for the first time. 1906, American Devres put the third electrode, the grid, into the Fleming diode, and invented the electronic triode, which was the most important milestone in early electronic technology. For more than half a century, electron tubes have made great contributions to the neutrality of electronic technology; However, electron tubes are expensive, complicated to manufacture, bulky and consume a lot of electricity. Since 1948, several researchers at Bell Laboratories invented the transistor, which gradually replaced the electron tube in most fields. However, we can't deny the unique advantages of electron tubes. In some equipment, regardless of stability, economy or power, electron tubes are needed.
1958 The world saw the first sample of an integrated circuit. The appearance and application of integrated circuits mark the development of electronic technology to a new stage. It realizes the unification of materials, components and circuits; It is essentially different from the traditional design and production methods of electronic components and the structure of circuits. With the development of integrated circuit manufacturing technology, the integration level is getting higher and higher, and large-scale and ultra-large-scale integrated circuits have appeared (for example, a complete computer can be made on a 6 square millimeter silicon chip), which further shows the advantages of integrated circuits. According to the integration degree of components (the number of components integrated on a chip), it can be divided into small integrated circuits (100 or more components) SSI, medium integrated circuits (100- 1000 components) MSI and large integrated circuits (1000-1).
With the development of semiconductor technology and the needs of scientific research, production, management and life, electronic computers came into being and became more and more perfect. Since the birth of the first electronic computer in 1946, it has experienced electron tubes, transistors, integrated circuits, large-scale integrated circuits and very large-scale integrated circuits, and its operation speed has reached billions of times per second. Now we are studying and developing the fifth generation computer (artificial intelligence computer). They don't work by programs, but by artificial intelligence. Especially since the advent of microcomputers in the 1970s, electronic computers have greatly accelerated their popularity because of their cheapness, convenience, reliability and compactness. Take the personal computer as an example, it has only gone through more than ten years since its birth, but its development has spanned many stages and entered thousands of households. Multimedia computers that integrate computers, televisions, telephones, fax machines and stereos have also come out. The information superhighway based on multimedia computers, optical cables and the Internet is another information revolution since the birth of computers. In the future, artificial intelligence will bring unprecedented changes to people's life and work style, and it has become a fashion to carry a microcomputer with you.
Digital control and digital measurement are also developing and widely used. After the development of NC machine tool 1952, it developed faster. "Machining Center" Multi-process CNC Machine Tool and "Self-adaptation"
Numerical control machine tools have appeared one after another. At present, the centralized control of dozens or even hundreds of CNC machine tools by electronic computers has been realized. With the improvement of the manufacturing technology of high-power semiconductor devices, power electronics technology has become a rapidly developing emerging science and technology. It is used in many aspects, such as intermediate frequency power supply, variable frequency speed regulation, DC transmission, uninterrupted power supply and so on, which makes semiconductors enter the high voltage field.
Electronic level is an important symbol of modernization, because industry is an important material basis for modernization. The development speed and technical level of electronic industry, especially the high development of electronic computers and their wide application in production fields, directly affect the construction of industry, agriculture, science and technology and national defense, and are related to the development speed of socialist construction and national security; It also directly affects the material and cultural life of hundreds of millions of people and concerns the vital interests of the broad masses of the people.
In order to further reduce the device volume and improve the device performance, people are constantly looking for advanced electronic materials. At present, advanced electronic materials have been discovered, such as bionic intelligent materials, nano-materials, advanced composite materials, low-dimensional materials (quantum dots, quantum wire cloth-based balls and cloth-based balls), high-temperature superconducting materials and bioelectronic materials. Advanced electronic materials are being used to manufacture new electronic equipment. The appearance of new electronic materials will make electronic technology develop to a higher level. These materials will make the future electronic devices functional and intelligent, and realize the integration of structure and function, further reduce the size of electronic devices, make them more functional and run faster, and lay the foundation for molecular devices, single electronic devices, molecular computers and biological computers.
Semiconductor diodes are used in almost all electronic circuits, which play an important role in many circuits. It is one of the earliest semiconductor devices and is widely used.
There are many kinds of diodes, which can be divided into germanium diode (Ge tube) and silicon diode (Si tube) according to the semiconductor materials used. According to different uses, it can be divided into detector diode, rectifier diode, zener diode, switching diode, isolation diode, Schottky diode, light emitting diode and so on. According to the die structure, it can be divided into point contact diode, surface contact diode and surface contact diode. A point contact diode is formed by pressing a thin metal wire on the smooth surface of a semiconductor wafer and applying a pulse current, so that one end of the contact wire is firmly sintered with the wafer to form a "PN junction". Because it is a point contact, only a small current (not more than tens of milliamps) is allowed to pass, which is suitable for high frequency and small current circuits, such as radio detection. The "PN junction" area of surface contact diode is large, which allows large current (several amperes to several tens of amperes) to pass, and is mainly used in "rectifier" circuits that convert alternating current into direct current. Planar diode is a special silicon diode, which can not only pass large current, but also has stable and reliable performance. It is often used in switches, pulses and high-frequency circuits.