The nemesis of the stealth fighter?
China's new materials will increase the radar detection range by 50 times
2018-08-04
Modern combat is a war based on electronic technology. Whoever has the advantage of electronic equipment can seize the electromagnetic power and seize it. The dominance of battlefield information. In the case of one-way transparency, the enemy is attacked. The performance of the electronic device is closely related to the material. For example, the F-16 and F-22 use active phased array radar, but the materials are completely different and the performance is very different. . The material mentioned here refers to the semiconductor material, which measures the main index power/mass ratio and reaction sensitivity of the semiconductor material. The former describes how much the device power is at a certain quality, and the latter describes the device's working state conversion and small signal detection capability. How strong, and China’s recent achievements in this area are likely to increase radar performance significantly.
The US F-22 airborne radar AN/APG-77 uses a semiconductor based on gallium nitride, and its electron mobility and mass-to-power ratio are improved relative to conventional GaAs radar. 5 to 10 times. This means that in the same radar and the same quality, the target can be detected more than 1.5 times the opponent's distance, which will inevitably bring great tactical advantages. Although China has successfully prepared gallium nitride crystals, it can be used in engineering. There are still gaps in materials, which also puts our military planes, ships and enemies at a disadvantage when they compete for electromagnetic power. A paper published by Professor Xu Yuzhen entitled "Interfacial Solution Method for Synthesizing Semiconductor Two-Dimensional Polymers" is very noteworthy, indicating that China has the ability to prepare two-dimensional semiconductor materials in the laboratory, and the power of this material will be large. Amplitude improves the performance of electronic devices.
The so-called two-dimensional semiconductor is relatively three-dimensional semiconductor, this semiconductor is very thin, only one by thickness The atomic composition of electrons in such semiconductors is very fast compared to bulk three-dimensional semiconductors. This is because, limited to the three-dimensional space environment, after the voltage is applied, although the electrons in the semiconductor partially move in a substantially certain direction, the whole will fly in a three-dimensional space, and most of the motion energy is consumed. In a two-dimensional semiconductor, electrons cannot move to the third dimension, which greatly increases the current. How much is this performance increase? The conclusion of the National Nanoscience Center paper is that the power quality ratio is 1000 times! Reaction sensitivity exceeds 6000 times! What does this mean? I will give you the calculation of this account.
The detection range of the radar is proportional to the power of the fourth power of the sensitivity. After using this material, the same volumetric radar will be able to achieve 50 times the existing radar! Taking the F-22 as an example, the RCS minimum value is 0.0001m2, which can reduce the detection distance of the existing radar to the normal fighter by 13 times. An airborne radar capable of detecting 150 kilometers can only find F near 10 kilometers. -22, but when the radar uses two-dimensional semiconductor materials, it can find the F-22 at 576km. Considering that the stealth capability of the stealth aircraft is almost at the limit, especially it is difficult to reduce the minimum value, so it can be said that once the species When the radar is put into production, the myth of the stealth plane can no longer be reproduced. In addition, it should be noted that this new material has the advantages of softness and plasticity. Under the influence of this feature, it is also possible to study the conformal radar antenna array that can be attached to the surface of the aircraft.
Two-dimensional semiconductor materials generally have thermal stability, which makes it possible to control by chemical methods, the general method It is a chemical vapor phase transport method that first synthesizes a semiconductor alloy block and then uses a mechanical lift-off method for preparation.
In the case of dichalcogenide, the chemical vapor transport method refers to placing a single component powder material and a certain amount of transport reagent in a vacuum quartz tube, and the quartz tube is placed in a certain amount. The temperature gradient of the reaction tube, and finally placed one end in a high temperature environment, one end placed in a low temperature environment, in the low temperature area will grow alloy monomer ingots. By repeated mechanical stripping, a two-dimensional disulfide material can be produced on a substrate of about 30 nm, but this method is rough, time consuming, and difficult to mass produce. Later, scientists invented physical vapor deposition and chemical vapor deposition.
Physical vapor deposition refers to the direct evaporation of a single component powder source at high temperatures and the deposition of condensation at low temperatures. A single-layer two-dimensional semiconductor material is obtained, and the temperature gradient in the deposition zone is extremely critical. If the operation is normal, a two-dimensional semiconductor film is finally obtained. Chemical vapor deposition refers to the use of an oxide and a material to be prepared as a reaction source, which is volatilized at a specific high temperature and undergoes a chemical reaction, and finally a film of a two-dimensional semiconductor material is deposited in the vicinity of the container.
The research group of Professor Xu Yuzhen is to improve the chemical vapor deposition method, using 1,4-trisonitrile to synthesize nitrile trimerization at the interface between dichloromethane and trifluoromethanesulfonic acid. Two-dimensional containing triazine polymer, this two-dimensional polymer has excellent dispersibility in organic solvents. This makes it possible to form a flexible polymer film with a fixed size by simply filtering, and even more magically, it can be suitably fabricated into a field effect transistor device and directly used for various electronic semiconductor components.
However, we should also see that the idea of developing this material is good, but it is still very practical. The road to the far is going. Two-dimensional semiconductor materials can only exist in a small part of the laboratory, which is costly, and there is currently no way to solve the problem of large-scale manufacturing. If you can make a few millimeters at a time, it is already at the top of the world. Moreover, the manufacture of a few millimeters has been to concentrate all the human and material resources of the entire laboratory for a long time. However, two-dimensional semiconductor materials are the development direction of future radar electronic systems, both China and the United States are engaged, but now they are just in their infancy.
