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Semiconductor materials of three generations

Semiconductor materials are a class of electronic materials that have semiconductor properties and the conductivity at room temperature is between conductive materials and insulating materials, they can be used to make semiconductor devices and integrated circuits.

 

Common semiconductor material characteristics:

Conductivity between conductors and insulators

When stimulated by external light and heat, its electrical conductivity will change significantly.

In a pure semiconductor, adding a small amount of impurities will sharply enhance its conductivity.

 

First Generation Semiconductor Materials:

Silicon (Si) and Germanium (Ge). Mainly used in various discrete devices, integrated circuits, new energy and chip manufacturing.

 

Second-generation semiconductor materials:

Mainly refers to compound semiconductor materials, such as gallium arsenide (GaAs), indium antimonide (InSb); ternary compound semiconductors, such as GaAsAl, GaAsP; and some solid solution semiconductors, such as Ge-Si, GaAs-GaP; glass semiconductors ( Also known as amorphous semiconductors), such as amorphous silicon, glassy oxide semiconductors; organic semiconductors, such as phthalocyanine, copper phthalocyanine, polyacrylonitrile, etc. It is mainly used to make high-speed, high-frequency, high-power and light-emitting electronic devices, and is an excellent material for making high-performance microwave, millimeter-wave devices and light-emitting devices. Due to the rise of the information superhighway and the Internet, it is also widely used in satellite communications, mobile communications, optical communications and GPS navigation.

 

Third-generation semiconductor materials:

Wide bandgap (Eg>2.3eV) semiconductor materials mainly represented by silicon carbide (SiC), gallium nitride (GaN), zinc oxide (ZnO), diamond, and aluminum nitride (AlN). The main applications are semiconductor lighting, power devices, microwave devices, lasers and detectors.

 

Components and integrated circuits made of semiconductor materials are important basic products of the electronics industry and have been widely used in various aspects of electronic technology. The production and scientific research of semiconductor materials, devices and integrated circuits have become an important part of the electronics industry. In terms of new product development and new technology development, the application areas are mainly Integrated Circuits, Microwave Devices and Optoelectronic Devices.

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Nanographene is Getting Smarter in Agriculture Application

In the era of rapid development of Internet technology, the future direction of agriculture has become the focus of social attention. Using information technology to change future agricultural production scenarios, let agricultural production develop in the direction of intelligence and spatial three-dimensionality, thereby promoting a new round of agricultural science and technology revolution, promoting the transformation of agricultural production methods and the efficient use of resources.

The intelligent application of graphene in agriculture is mainly reflected in the following three aspects:

Application in greenhouse.

As a new heating method, nano-graphene heating is not only used in home life, but also has a wide range of applications in agriculture and rural areas, covering vegetable greenhouses, flower cultivation, agriculture and forestry nursery, soil insulation, chick hatching, special aquaculture and other industries. Greenhouse is the most popular production method in my country’s facility agriculture, which not only greatly improves the productivity of the land, but also solves the problem of off-season production. But the biggest trouble is that most of the greenhouse heat sources use hot blast stoves, heating stoves or electric heating wires. Not only high energy consumption, large pollution, but also poor stability and high cost. The graphene electrothermal film system has a high electrothermal conversion rate, which generally saves 30-50% of energy and will not cause pollution. After the graphene electrothermal film is covered with soil, far-infrared direct warming can significantly promote the development of seedlings and effectively enhance photosynthesis.

Smart farmland system

The farmland is covered with sensors to collect surrounding environmental parameters such as air temperature and humidity, soil temperature and humidity. If the land is short of water, the system will automatically give an early warning, and the manager can water it with one button on the mobile phone, which can be operated anytime, anywhere. It is no longer a fantasy that agricultural production becomes intelligent. Therefore, the smart farmland system not only makes agricultural production management more intelligent, but also makes the utilization of farmland resources more reasonable.

The main component of the smart farmland system is the sensor. Sensor technology is used worldwide for detecting and monitoring process parameters. Graphene sensors also work in the same way, it’s just a factor of the nanomaterials used in their fabrication. Sensors are a very important application field of graphene. Graphene sensors can convert environmental parameters into electrical signals processed and measured by computers. This feature meets the management needs of smart farmland. There are many advantages when people apply graphene sensors in smart farmland. Therefore, graphene sensors are the way to open the transformation and upgrading of smart agriculture. Graphene is known as the “king of new materials” because of its excellent properties, such as superconductivity, good flexibility, good transparency, and excellent mechanical properties. It is widely used in all walks of life.

Raising seedlings and adsorbing pollutants

Based on domestic and foreign research, appropriate addition of nano graphene powder to soil is beneficial to seed germination and seedling growth, and is beneficial to improve crop yield and quality. The addition of graphene nanomaterials to fertilizers can increase the clay content of the soil and improve the soil texture, and the nanocarbon has a large specific surface area, which can improve the adsorption force of the soil on nutrient elements, thereby effectively controlling the above-ground nutrient volatilization, surface runoff and Loss of deep seepage. At the same time, nano-carbon can improve the electrochemical properties of soil and promote the absorption of nutrients by the root system, thereby improving the utilization rate of fertilizers, reducing agricultural non-point source pollution, and ultimately saving fertilizers and increasing efficiency.

Graphene nanomaterials also play an excellent role in the adsorption and purification of agricultural pollutants, especially for pesticide and heavy metal pollution in water.

 

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Graphene-hexagonal Boron Nitride Heterostructure Enables Ultra-fast Heat Transfer

Nano heat flow plays an important role in modern electronic and optoelectronic applications such as thermal management, photodetection, thermoelectricity, and data communication. Two-dimensional layered materials are beginning to consolidate their fundamental position in many applications. The van der Waals heterostructure is composed of different layered two-dimensional materials stacked. These stacks can be composed of materials with different physical properties, and the interface between the materials is super clean and has a clear outline.

 

Supported by the European Union’s “Graphene Flagship” program, the Spanish Institute of Photonics prepared a van der Waals heterostructure composed of hexagonal boron nitride encapsulated  gaphene nano powders, a two-dimensional dielectric material, and successfully observed and tracked the heat generated between the van der Waals heterostructures in real time. transmission. The researchers discovered a surprising phenomenon: the heat flow does not stay in the graphene layer, but flows to the surrounding hexagonal boron nitride layer. The heat transfer time is very fast, on the order of picoseconds. The research results were published in “Nature · Nanotechnology”.

 

The heat transfer process is realized by coupling the hot electrons excited by light irradiating graphene with the hyperbolic phonon-polarization excimer in the hexagonal boron nitride sheet. These phonon polaritons propagate in the hexagonal boron nitride sheet, just like light propagates in an optical fiber, but are limited to nano-scale infrared light. The results show that these bizarre hyperbolic modes are very effective heat dissipation methods.

 

The research results will have a profound impact on the application of graphene based on hexagonal boron nitride packaging (also the next-generation graphene application platform). In particular, this technology will provide direction for optoelectronic device design to make full use of heat flow, get more Carbon Material Nanopowders from https://www.hwnanomaterial.com quickly!.

 

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Nano materials in concrete

Application of nanotechnology in concrete

Concrete is the basic building material and widely used in a variety of buildings and structures. Since the 21st century, concrete engineering is upsizing, the engineering environment becomes complicated, and the ever-expanding application fields, people have put forward higher requirements for concrete materials. Nanotechnology can improve the performance of concrete and greatly expand the application.

Nanomaterials can effectively improve the performance of concrete

1. Nano silica/SiO2
Nano SiO2 powder is a superfine powder with silicon or silicone chloride hydrolyzed to form hydroxyl groups on the surface. In the field of cement concrete, nano silica can increase the strength and durability of concrete due to its strong pozzolanic activity, micro-aggregate filling effect and nucleation.

2. Carbon nanotubes
The carbon nanotubes are tubular, light in weight, and the hexagonal structure is perfectly connected, which is a good high-strength fiber material. The proper amount of carbon nanotube powder into the cement can effectively improve the pore structure and microcracks of the material, and play a bridging role, thereby improving the mechanical properties of the cement substrate. get details about carbon nanotubes price from https://www.hwnanomaterial.com/.

3. Nano calcium carbonate
Nano CaCO3 is a low-activity mineral micropowder material with a cost of about one-tenth that of nano-SiO2. After being doped with nano calcium carbonate powder, under the combined action of micro-aggregate effect and crystal nucleus effect, the bulk density is increased, which helps to improve the flexural and compressive strength. The nucleation of nano-calcium carbonate can refine the crystal form, improve the interface structure and improve the durability of concrete.

4. Nano carbon fiber
Nano-carbon fiber is a novel nano-carbon material which is formed by the rolling of a layered graphite sheet. Compared with carbon nanotubes, it has a relatively low cost and has a great advantage in production. Study found that the addition of nano-carbon fiber not only makes the concrete have excellent pressure-sensitive properties, but also improves its mechanical properties.

Nanotechnology expands the application of concrete
1. Concrete that absorbs electromagnetic waves
2. Purifying air concrete
3. Antibacterial concrete
4. Automatic humidity control concrete
5. Ecological concrete
6. Smart concrete

High-performance, high-functionalized concrete as a high-tech in the field of building materials provides a new opportunity for the development of traditional building materials. The development of traditional concrete materials is entering the track of technological innovation. Among them, nanomaterials and nanotechnology will play an increasingly important role in improving the durability and functionality of concrete.

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Graphene helps prevent steel from rusting

An Indian-American researcher and his partner invented a new technology that uses graphene to prevent steel from rusting.

Iron and steel rust is a big problem in the automotive industry. Although there is paint coverage, it is easy to scratch, and the bumper is coated with chromium. This process involves the addition of toxic chemicals.

In order to solve this problem, SUBA Buffalo professor of chemistry Sarbajit Banerjee and doctoral student Robert Dennis developed a polymer composite containing graphene.

Graphene is a layer of carbon atoms, it has hydrophobicity and strong conductivity. These properties make the steel contact with water and also reduce the electrochemical reaction of iron oxides that rust iron.

The two researchers added this composite coating to a varnish, applied it to steel, and then immersed it in salt water. In a typical winter climate, the mixture of salt water and salt and snow is different and a car will encounter a car, so it is very effective as a very harsh environmental avatar.

Initially, varnished steel sheets could only last in salt water for several days. However, Banerjee and Dennis can keep varnish in this environment for a month by adjusting the concentration and dispersion of added graphene.

Banerjee said that he wanted to add something to the coating that detects the pH of the water in the vicinity of the scratches and reacts with the water in a manner that seals the crack.

Although this technology still has a long way to go for commercialization, some large companies in the steel industry are also interested in participating in this research, especially Tata Steel, which has provided funding for Banerjee’s experiments. The two scientists also received $50,000 in funding from the New York State Institute of Pollution Prevention.

In a news release, Banerjee stated that the paint can be produced using the existing equipment of the local steel plant.

Unlike hexavalent chromium, used to coat bumpers and some engines, graphene is non-toxic because it is only a carbon atom and does not require the use of strong acids. It is safe throughout the process. These reasons make graphene a magic material for future electronic components.

Related reading:Carbon Material Nanopowders  Carbon Nanomaterials