We are talking about alternatives for silicon.
/ photo Unsplash
Moore's law, Dennard's regularity and Kumi's rule lose relevance. One reason is that silicon transistors are approaching their technological limit. We have covered this topic in detail. . Today we are talking about materials that in the future can replace silicon and extend the validity of the three laws, which means increasing the efficiency of processors and computing systems using them (including servers in data centers).
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Carbon nanotubes
Carbon nanotubes are cylinders, the walls of which consist of a monatomic layer of carbon. The radius of carbon atoms is smaller than that of silicon, so nanotube-based transistors have greater electron mobility and current density. As a result, the speed of the transistor increases and its power consumption decreases. By engineers from the University of Wisconsin-Madison, productivity increases fivefold.
The fact that carbon nanotubes have better characteristics than silicon has long been known - the first such transistors appeared . But only recently, scientists managed to get around a number of technological limitations in order to create a sufficiently effective device. Three years ago, physicists at the aforementioned University of Wisconsin unveiled a nanotube-based transistor prototype that outperformed today's silicon devices.
One of the applications of devices based on carbon nanotubes is called flexible electronics. But so far, the technology has not gone beyond the laboratory, and there is no talk of its mass introduction.
Graphene nanoribbons
They are narrow strips. a few tens of nanometers wide and one of the main materials for creating transistors of the future. The main property of a graphene tape is the ability to accelerate the current flowing through it using a magnetic field. At the same time, graphene higher electrical conductivity than silicon.
On , processors based on graphene transistors will be able to operate at frequencies close to terahertz. While the frequency of modern chips is set within 4-5 gigahertz.
The first prototypes of graphene transistors . Since then engineers processes of "assembly" of devices based on them. More recently, the first results have been obtained - a team of developers from the University of Cambridge in March about launching into production . Engineers say that the new device can speed up the work of electronic devices ten times.
Hafnium dioxide and selenide
Hafnium dioxide is used in the production of microcircuits . An insulating layer is made from it on the transistor gate. But today, engineers offer to optimize the operation of silicon transistors with it.
/ photo PD
At the beginning of last year, scientists from Stanford that if the crystal structure of hafnium dioxide is reorganized in a special way, then its (responsible for the ability of the medium to pass an electric field) will increase by more than four times. If such a material is used to create transistor gates, it is possible to significantly reduce the influence .
Also American scientists reduce the size of modern transistors using hafnium and zirconium selenides. They can be used as an effective insulator for transistors instead of silicon oxide. Selenides are much thinner (three atoms) while maintaining a good band gap. This is an indicator that determines the power consumption of the transistor. Engineers already several working prototype devices based on hafnium and zirconium selenides.
Now engineers need to solve the problem with the connection of such transistors - to develop appropriate small contacts for them. Only after that it will be possible to talk about mass production.
Molybdenum disulfide
By itself, molybdenum sulfide is a rather poor semiconductor, which is inferior in properties to silicon. But a group of physicists at the University of Notre Dame have discovered that thin films of molybdenum (one atom thick) have unique properties - transistors based on them do not pass current in the off state and require little energy to switch. This allows them to operate at low voltages.
Molybdenum transistor prototype in the laboratory. Lawrence at Berkeley in 2016. The width of the device is only one nanometer. Engineers say such transistors will help prolong Moore's law.
Also a molybdenum disulfide transistor last year engineers from a South Korean university. It is expected that the technology will find application in the control circuits of OLED displays. However, there is no need to talk about the mass production of such transistors yet.
Despite this, Stanford researchers that modern infrastructure for the production of transistors can be rebuilt at minimal cost to work with "molybdenum" devices. Whether such projects will be realized remains to be seen in the future.
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Source: habr.com