In the contest between China and the "foreign" country, which country has the upper hand? Some say that China hangs and beats foreign countries, while others say that foreign countries easily push China to the ground and rub it against the ground. Of course, centrists must say that both countries have pros and cons, but this conclusion, while correct, is not nutritious. If you want to appear knowledgeable on the topic of China and foreign countries, you must first understand what technology is?
Яка основна технологія?
Divide the technology into different categories. The first category is called "Copycat Technology", or "Pure Burning Technology". Some people like to burn to the left, while others like to burn to the right, so different application technologies are created. This is essentially a combination of old technology and new things, such as the Saturn V that landed on the moon, the geotechnical sea bridge, the mustache rat tank, and even the Great Wall of China and the pyramids of Egypt. For example, this is a bit like the Guinness Book of Records: the longest hair, the longest nails, etc... For this kind of thing, as long as the money is in place, anyone can burn it, the key depends on whether there is demand, so these can also be called applied technology.
After the fortune of geotechnical industry, there was a huge demand, which promoted the blowout of various application technologies that burn money. After earning money, they could tirelessly improve various details. Therefore, it can be said without bragging that China's application technology has been on an equal footing with that of the whole foreign countries.
The second type of technology is temporarily called "non-copycat technology", or "burning money and burning time technology". If you try to dismantle any awesome equipment, you will eventually find that it is a material technology.
The ingredients are similar to cooking. I can tell you the ingredients of tomato scrambled eggs, but the dishes you cook are not as delicious as mine. This is the core technology. In addition to biomedicine, the core technology is material technology in the final analysis. See a bunch of examples:
The engine, the jewel in the crown of the industry, is the most criticized shortcoming of geotechnical engineering. To put it bluntly, its core technology is that the turbine blades are not strong enough, and if the accelerator is stepped on hard, it will fall apart. Whether it is an aerospace engine, aero engine, or a gas turbine, as long as the word "machine" is included, the geotechnical waist rod is a bit soft (you can refer to the previous article "Materials". The Tragedy: Dystocia Chinese Heart").
In addition to burning money and time, material technology sometimes requires luck. Let's take the engine as an example: metal rhenium, which is mixed with nickel, makes turbine blades that are suspended in the sky. The global proven reserves of rhenium are about 2,500 tons, mainly distributed in Europe and the United States, and 70 percent are used for engine turbine blades. , this kind of strategic material was properly embargoed by the US imperialists. A few years ago, a rhenium mine with a reserve of 176 tons was discovered in Shaanxi, but the geotechnical workers immediately worked hard to burn money, and the hard life has only improved in the past few years.
Rare earth permanent magnets are magnets made of rare earths, which can maintain magnetic properties all the time and are very useful. Most of the high-grade rare earth ores are distributed in China, so geotechnical technologies related to "magnetism" are more difficult than the US imperialists, such as nuclear fusion, dark matter detection in space, etc. It is said that Geotech also imposed an embargo on the US imperialists a few years ago, forcing the US imperialists to exchange rhenium, plus the bit of rhenium that was dug out of Shaanxi Anhui, the J20 engine is considered a bit of an eye. Some eyebrows.
As the "mother of industry" high-end machine tools, geotechnical engineering is basically at the same level as the national football team, and can only look up to Japan, Germany and Switzerland. Material is one of the biggest limitations. For example, during high-speed machining, the friction between the spindle and the bearing produces thermal deformation, which causes the spindle to lift and tilt, and the tool wears, etc., so the work that requires extremely high machining accuracy is still expected." Yang" sighed.
Optical crystals and some geotechnical products can also be embargoed against the US imperialists, so light-related technologies are not weak, such as laser weapons and quantum communication. The aerodynamic shape benefits from the accumulation of Qian Xuesen's generation, and the related technologies are also leveraged.
If we continue to list, we will find that China still lags behind foreign countries in the application of broad basic materials, and China gradually leads the application in relatively narrow segments.
Sitting upright, little friends, here comes the point! There are about 130 kinds of this key core material in the world, that is to say, as long as you have these 130 kinds of materials, you can assemble any equipment that exists in the world, and then produce anything that exists.
The core technology of human beings, to a certain extent, refers to these 130 kinds of materials, of which 32 percent are completely blank in China, and 52 percent rely on imports. Domestic production is achieved, but 95 percent of the equipment for producing parts is imported. These are not things about Chen Shimao's rotten millet, but the data released by the Ministry of Industry and Information Technology in July 2018, which are still fresh.
Core material technology, it is not too much to say that "foreign countries still hold China to the ground". This is actually very easy to understand. After all, it has not been a long time to make a fortune, and material technology not only burns money, but also burns time.
It must be emphasized here that application technology is not less important than core technology. It requires a combination of capital, demand and social reality. Although foreign countries have the ability to burn them, they may never have the opportunity to burn them in a lifetime. Someone must have raised the bar here: they just don't want to burn, or they will kill you in minutes! Hehe, if you forcibly burn money, the consequences will follow Lao Maozi.
After a long time, it's time to get back to the point. The reason why semiconductor chips are difficult is because it involves not only a lot of application technologies that burn money, but also many material technologies that burn money and time. In order to facilitate the understanding of the little pot friends, this must start from the principle.
Принципи мікросхем і квантова механіка
Many illiterate people think that quantum mechanics is just a mathematical game and has no application value. Hehe, let's find an ancestor for computer chips. Please see the demonstration:
Conductors, we can understand, insulators, we can also understand, the first time the little friends were confused by physics, I am afraid it is semiconductors, so I will pay the debt for your physics teachers first.
When atoms form a solid, there will be many identical electrons mixed together, but quantum mechanics believes that two identical electrons cannot stay in one orbit, so in order to keep these electrons from fighting in one orbit, many orbits are split into There are several tracks, so many tracks are crowded together, and if they are accidentally close together, they become a wide and large track. This kind of wide orbit made of many thin orbits squeezed together is called energy band.
Some wide orbits are so crowded with electrons that they cannot move, and some wide orbits are so empty that electrons can move freely. The electrons can move, and the macroscopic performance is electrical conduction. Conversely, the electrons cannot move and cannot conduct electricity.
Well, let's keep things simple, without mentioning the concepts of "valence band, full band, forbidden band, and conduction band", and prepare to circle the key points!
Some full orbitals and empty orbits are too close together, and electrons can easily run from the full orbit to the empty orbit, so they can move freely. This is a conductor. The electrical conductivity of monovalent metals is slightly different.
But in many cases, there is a gap between the two wide orbitals, and the electrons can't cross it by themselves, so they do not conduct electricity. However, if the width of the gap is within 5ev, adding extra energy to the electron can also cross the empty orbit, and it can move freely when it crosses over, that is, conduct electricity. This kind of solid with a gap width of no more than 5ev can sometimes conduct electricity and sometimes cannot conduct electricity, so it is called a semiconductor.
If the gap exceeds 5ev, it will basically have to stop. Under normal circumstances, electrons cannot pass through. This is an insulator. Of course, if the energy is large enough, let alone the gap of 5ev, 50ev will still run through, for example, high-voltage electricity breaks down the air.
At this point, the energy band theory developed by quantum mechanics has almost taken shape. The energy band theory systematically explains the essential difference between conductors, insulators and semiconductors, that is, depending on the gap between the full orbital and the empty orbital, the academic point said , depending on the forbidden band width between the valence and conduction bands.
Semiconductors are still far from the principle of chips, don't worry.
Obviously, a straight man like a conductor has nothing to mess with, so the wire is still copper wire to this day, there is no technical progress, and the fate of the insulator is similar.
The ambiguous character of semiconductor is the easiest to do things, so the industries related to electronic equipment basically belong to the semiconductor industry, such as chips and radar.
Scientists use silicon as the base material for semiconductors for a few simple reasons. The outer shell of silicon has 4 electrons, and if a solid consists of 100 silicon atoms, then its full orbital is packed with 400 electrons. At this time, 10 silicon atoms are replaced with 10 boron atoms, and the outer layer of trivalent elements such as boron has only 3 electrons, so the full orbital of this solid has 10 vacancies. This is equivalent to freeing up a few empty seats on a crowded bus, providing conditions for the movement of electrons. This is called a P-type semiconductor.
In the same way, if 10 silicon atoms are replaced by 10 phosphorus atoms, there are 5 electrons in the outer shell of a pentavalent element such as phosphorus, so there are 10 more electrons in the full orbital. It is equivalent to 10 more people hanging outside the crowded bus. These people are very easy to get off the bus. This is called N-type semiconductor.
Now, what happens when the two semiconductors, PN, are placed face to face? Needless to say, the extra electrons of the N-type must go to the vacancies of the P-type until the electric field is balanced, which is the famous "PN junction".
