Graphene functional semiconductors debuted
Smaller and faster can be used for quantum computing
Graphene is a monolayer of carbon atoms linked together by the strongest known bonds. Semiconductors are materials that conduct electricity under certain conditions and are the basic components of electronic devices. At present, in order to meet the needs of faster and faster computing speeds and smaller and smaller electronic devices, silicon, a common material used in modern electronic products, has reached its limit. To this end, researchers at Tianjin University in China and the Georgia Institute of Technology in the United States have made the world's first functional semiconductor from graphene. This semiconductor is compatible with traditional microelectronic processing methods, which is also necessary to replace silicon.
Researchers began to explore the semiconductor potential of carbon-based materials early on, turning to graphene research in 2001. Graphene is a very strong material that can handle very large currents, and the team wanted to bring the properties of graphene to electronics. It is reported that the team overcame the biggest obstacle that has plagued graphene research for decades, and the reason why many people think that graphene electronics will never work - "band gap". A long-standing problem in graphene electronics is that graphene does not have the right bandgap and cannot be opened and closed at the correct ratio. Over the years, many people have tried various methods to solve this problem. In the latest research, the team's technology achieves a bandgap, a key step in the development of graphene-based electronics.
(The content of the article comes from the Internet)
Specifically, the research team made a breakthrough in growing graphene on silicon carbide wafers using a special furnace. They produced epitaxial graphene, which is a monolayer that grows on the crystal plane of silicon carbide. It has been found that when properly manufactured, epitaxial graphene chemically bonds to silicon carbide and begins to exhibit semiconductor properties. But to make a functional transistor, a lot of manipulation is required on the semiconductor material, which can compromise its performance. To demonstrate that their platform could function as a viable semiconductor, the team needed to measure its electronic properties without damaging it. They put atoms on graphene and used doping techniques to "donate" electrons to the system to see if the material was a good conductor – it would work without damaging the material or its properties.
The team's measurements showed that their graphene semiconductors were 10 times more mobile than silicon. In other words, electrons move with very low resistance, which in electronics means faster calculations. Finally, the researchers say that epitaxial graphene could lead to a paradigm shift in electronics and allow for entirely new technologies that take advantage of its unique properties. This material can take advantage of the quantum mechanical wave properties of electrons, which is necessary for quantum computing.
Measurements show that graphene semiconductors have ten times more room-temperature electron mobility than silicon. This means faster switching, which may make GPUs, CPUs, and other devices more efficient in completing computing tasks. In addition, the strong chemical, mechanical, and thermal properties of graphene semiconductors compared to traditional materials can enhance the durability and reliability of electronic products.
There are also new discoveries of graphene in China
It is expected to be applied to optoelectronic modulators and optoelectronic chips
Recently, researchers from the Institute of Physics of the Chinese Academy of Sciences, the National Center for Nanoscience and other units have made an important breakthrough by studying the diamond-shaped stacking structure of three-layer graphene. They found that there is a strong interaction between electrons and infrared phonons in the diamond-shaped stacking of three-layer graphene, which is expected to be applied to fields such as optoelectronic modulators and optoelectronic chips.
In recent years, three-layer graphene has attracted a lot of attention from researchers. In general, three-layer graphene can exhibit two different stacking geometries, namely diamond stacking and Bernal stacking. "The three layers of graphene stacked in these two stacks have completely different symmetry and electronic properties, such as the three-layer graphene of the center-symmetrical diamond-shaped stack has an adjustable energy gap of the displacement electric field, and can exhibit a series of associated physical effects that Bernal's stacked three-layer graphene does not have: Mott insulating state, superconductivity, ferromagnetism, etc." ”
(The content of the article comes from the Internet)
A new approach to development
Used to grow graphene nanoribbons
Graphene was first experimentally discovered in 2004, bringing the dawn to the development of high-performance electronic devices. Graphene is a two-dimensional crystal composed of a single layer of carbon atoms arranged in a honeycomb pattern, with a unique electronic band structure and excellent electronic properties. The electrons in graphene are massless Dirac fermions, which can shuttle at extremely fast speeds, and the carrier mobility of graphene can reach more than 100 times that of silicon. Graphene-based "carbon-based nanoelectronics" is expected to usher in a new era of human information society. However, 2D graphene does not have a bandgap and cannot be used directly to make transistor devices.
Theoretical physicists have proposed that the band gap can be introduced through the quantum confinement effect by cutting two-dimensional graphene into quasi-one-dimensional nanobands. The band gap size of graphene nanoribbons is inversely proportional to their width, and graphene nanoribbons with a width of less than 5 nanometers have a bandgap size comparable to that of silicon, making them suitable for making transistors. These graphene nanoribbons, which have both a band gap and ultra-high mobility, are one of the ideal candidates for carbon-based nanoelectronics.
To this end, researchers have devoted a lot of energy to the preparation of graphene nanoribbons. Although a variety of methods have been developed for the preparation of graphene nanoribbons, the problem of preparing high-quality graphene nanoribbons for semiconductor devices has not been solved, and the carrier mobility of the prepared graphene nanoribbons is much lower than the theoretical value. On the one hand, this difference comes from the low quality of the graphene nanoribbons themselves, and on the other hand, from the disorder of the surrounding environment of the nanoribbons, due to the low-dimensional properties of the graphene nanoribbons, all their electrons are exposed to the external environment, so the movement of electrons is extremely susceptible to the surrounding environment.
In order to improve the performance of graphene devices, various methods have been tried to reduce the disorder effect caused by the environment. The most successful method to date is hexagonal boron nitride encapsulation. Boron nitride is a wide-bandgap two-dimensional layered insulator with the same honeycomb hexagonal lattice as graphene. What's more, boron nitride has an atomically flat surface and excellent chemical stability. If the graphene clamp is encapsulated between two layers of boron nitride crystals to form a sandwich structure, the graphene "sandwich" will be isolated from the "water, oxygen, and microorganisms" in the complex environment outside, so that the "sandwich" can always be kept in the "best quality and fresh" state.
(The content of the article comes from the Internet)
Several studies have shown that graphene encapsulated with boron nitride can significantly improve a number of properties, including carrier mobility. However, the existing mechanical packaging method is very inefficient, and can only be used in the field of scientific research at present, which is difficult to meet the needs of large-scale production in the advanced microelectronics industry in the future. Experimental observations show that the growth of graphene nanoribbons only occurs at the particles of the catalyst, and the position of the catalyst remains unchanged throughout the process. This indicates that the end of the nanoribbon exerts a push force on the graphene nanoribbon, causing the entire nanoribbon to slide continuously over the friction between it and the surrounding boron nitride, so that the tip gradually moves away from the catalyst particles. Therefore, the researchers speculate that the friction experienced by the graphene nanoribbons as they slip between the layers of boron nitride atoms must be very small.
Since the grown graphene nanoribbons are "encapsulated in situ" with insulating boron nitride, which is protected from adsorption, oxidation, environmental contamination, and photoresist contact during device processing, ultra-high-performance nanoribbon electronics can theoretically be obtained.
Practical application
Graphene nanoribbon epoxy coating
For winter flights, an important natural enemy that affects flight safety is the icing of aircraft wings. When the aircraft is parked at the airport, the staff can use a special de-icing fluid to de-ice the wings, but when the aircraft encounters ice at high altitude, there is no ideal solution. Recently, scientists at Rice University in Texas, USA, have created a new graphene nanoribbon epoxy coating, which can melt the ice through the generated electric heat after being applied to the voltage. The researchers combined an epoxy coating with graphene nanoribbons. Graphene nanoribbons are two-dimensional crystals composed of a single layer of carbon atoms, and the researchers prepared these flat graphene nanoribbons with excellent electrical conductivity.
In laboratory tests, the researchers set the temperature at minus 20°C and applied an epoxy coating to the edges of the helicopter rotor blades, and when a small voltage was applied, the surface of the coating generated an electric heat of up to 93°C, which can melt more than 1 centimeter of ice. In addition, the coating provides an electromagnetic shield to the aircraft, helping to protect the aircraft from lightning strikes.
Graphene material
Safe R&D with a glove box
1. Biocompatibility: The implantation of carboxyl ions can make the surface of graphene materials have active functional groups, thereby greatly improving the cellular and biological reactivity of the materials. Graphene is in the form of a thin yarn, which is more suitable for the study of biomaterials than the tubular shape of carbon nanotubes. Compared with carbon nanotubes, the edge of graphene is longer, easier to be doped and chemically modified, and easier to accept functional groups.
2. Oxidation: It can react with active metals.
3. Reducibility: It can be oxidized in the air or by oxidizing acids, and graphene can be cut into small fragments by this method. Graphene oxide is a layered material obtained by the oxidation of graphite, and the separated graphene oxide sheet structure is easily formed by heating or ultrasonic exfoliation in water.
Although graphene has a relatively stable structure with a carbon-carbon bond of only 1.42, a safe experimental environment is still needed due to its chemical properties: a graphene glove box
The Lab2000 glove box is a high-performance, high-quality closed-loop work system that automatically absorbs water and oxygen molecules and purifies the working environment, providing a 1ppm O₂ and H₂O inert atmosphere to meet your specific cleaning requirements. The system is an economical circulating purification system designed for graphene research and development: it includes a closed box, a transfer chamber, a rotary vane vacuum pump and a circulating purification system with an integrated microcontroller control panel. The standard Lab2000 system is equipped with an inert gas cleaning system equipped with a set of cleaning columns (fully automatic and renewable) to purify and maintain the gas environment inside the glove box.
More graphene materials are developed safely
Keep an eye on the Atex glove box