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Warm hints: The word in this article is about 1000 and the  reading time is about 6 minutes.SummaryFujitsu,a company that provide innovative IT services and digital technologies like mobile,AI,cloud or etc,announced the development of a gallium-nitride(GaN) high-electron mobility transistor(HEMT) power amplifier for use in W-band(75-110 GHz)transmissions in July 2017 at the 12th international Conference. To realize long-distance,high-capacity wireless communications,a promising approach is to utilize the W-band and other high frequency bands that encompass a broad range of usable frequencies, and increase output with a transmission power amplifier. At the same time, demand exists for improved efficiency in power amplifiers in order to mitigate the increased power consumption of communication systems. Fujitsu has now succeeded in developing a power amplifier for use in W-band transmissions that offers both high output power and high efficiency, improving transistor performance through the reduction of electrical current leakage and internal GaN-HEMT resistance. Fujitsu has achieved 4.5 watts per millimeter of gate width, the world's highest output density in the W-band, and has confirmed a 26% reduction in energy consumption compared to conventional technology. Fujitsu anticipates that setting this power amplifier between wireless communication systems in two locations will achieve high-bandwidth communications at 10 gigabits per second (Gbit/s) over a distance of 10km. Part of this research was carried out with support from Innovative Science and Technology Initiative for Security, established by the Acquisition, Technology & Logistics Agency (ATLA), Japan Ministry of Defense. Development Background Wireless data traffic from mobile communications has increased dramatically over the last few years, and with the spread of 5G and IoT devices it is predicted to increase at an annual growth rate of 1.5 times until the year 2020. In order to build this sort of high capacity next-generation wireless communications network, attention has been focused on wireless communication technology using the high frequency W-band. The range of frequencies that can be used in the W-band is very broad, and because communication speed can be rapidly increased in this band, it is well-suited for this kind of high bandwidth wireless communication. Conventional wireless communications technology, has allowed for performance of several Gbit/s over distances of several kilometers, but achieving an even greater increase in wireless communication distance and capacity utilizing the W-band demands further increases to the output of power amplifiers to boost signals during transmission. Issues To increase distance and capacity, it will be necessary to expand the frequency bandwidth that can be amplified while simultaneously supporting modulation methods that can transmit more information within the same frequency bandwidth, and a strong requirement is to have less distortion when the signal is amplified. Another pursuit is keeping in check the energy consumption of communication systems that accompanies greater distances and capacities, and the improved energy efficiency in power amplifiers.In order to both increase the distance and capacity of wireless communications and decrease energy consumption with indium-aluminum-gallium-nitride (InAlGaN) HEMTs, Fujitsu has developed two technologies that effectively reduce internal resistance and current leakage. Features of the newly developed technologies are as follows: Technology to reduce internal resistance Fujitsu has developed device technology that can reliably reduce resistance to one tenth that of previous technology when current flows between the source or drain electrodes and the GaN-HEMT device. The technology utilizes a manufacturing process that embeds GaN plugs directly below the source and drain electrodes, which generate electrons at high densities (fig. 1). It is necessary to transport the electrons that come from the source electrode to the two dimensional electron gas field as smoothly as possible. The structure of the previous technology causes the electron supply layer to become a barrier, however, and internal resistance increases between the source electrode and the two dimensional electron gas. By applying this new technology, Fujitsu succeeded in running high currents through the transistor with significantly less resistance (fig. 2). Technology to control current leakageA current leakage occurs when the two dimensional electron gas, which moves at high speed on the boundary at the top of the channel layer, takes a detour below the gate when the transistor is in its off-state. This leakage causes deterioration in the operational performance of the power amplifier. Normally, it is possible to reduce current leakage by placing a barrier layer beneath the channel layer, but in that case the amount of two dimensional electron gas also decreases, and leads to a reduction of the drain current. This new technology maintains high drain currents by effectively distributing indium-gallium-nitride (InGaN) to create a barrier layer below the channel layer. This reduces electron detours during operation, successfully providing significant reductions in current leakage(just see the fist and second picture).Effects The previous world record for power amplifier output density in the W-band for transmitters was 3.6 watts per millimeter of gate width with technology developed by Fujitsu Laboratories. This has improved significantly with the newly developed technology, which delivers power output of 4.5 watts per millimeter of gate width for a power amplifier designed to operate at 94GHz. In addition, this new technology achieved a reduction in energy consumption of 26% compared to the previous technology through a reduction in current leakage. It is anticipated that the use of this power amplifier will allow the achievement of high capacity, long distance wireless communications between two connected systems at different locations at over 10Gbit/s and at distances greater than 10km.Fujitsu aims to apply this technology broadly to the development of power amplifiers for purposes that call for wireless communications that offer long range and higher capacity, while offering easier installation than fiber optics. The goal is to commercialize this technology in high speed wireless communication systems by 2020, with an aim to employ it in such situations as a method of restoring communications when fiber optic cables have been severed by natural disasters or as a way of setting up temporary communications infrastructure when holding events.  Article provide by FujitsuArticle edited by kynix

When in 2006, researchers at Harvard University, US, said they have made the best nanowire transistors to date. The devices consisted of germanium/silicon core/shell nanowire field-effect transistors (FETs) using high-κ dielectrics and a metal top gate geometry.  "We showed that our current Ge/Si nanowire FETs perform three to four times better than silicon CMOS [devices]," Charles Lieber of Harvard told nanotechweb.org, "thus demonstrating for the first time that there is a clear advantage to nanowire versus conventional planar FETs. This justifies further (aggressive) work on the nanowire FETs and, by reporting results in an industry standard, we hope we will also make industry better aware of the potential of this basic research." Lieber and colleagues used band structure design to create a hole gas in the Ge/Si core-shell system. "This has proved to be an ideal system with reliable ohmic contact and high mobility," said Lieber. The researchers employed a benchmark typically used by the semiconductor industry to characterize the on-current and intrinsic delay properties of their devices. The transistors exhibited a scaled transconductance of 3.3 mS µm-1 and on-current of 2.1 mA µm-1. Hole mobility, meanwhile, was 730 cm2 V-1 s-1 – 10 times higher than that of a silicon p-metal-oxide semiconductor field effect transistor (MOSFET). What's more, according to the scientists, the device's intrinsic switching delay was comparable to that of similar length carbon nanotube field-effect transistors and much better than the length-dependent scaling of planar silicon MOSFETs. Lieber reckons the devices could have applications in next-generation high-speed logic circuits after conventional CMOS technology hits its limits. "In addition, the high-performance nanowire transistors can also [work] on many unconventional substrates, such as glass or plastic for transparent or flexible applications, where conventional crystalline Si technology is not possible," he added. "The excellent mobility exhibited by the nanowires would greatly improve device speed for these applications." Now the researchers plan to improve the performance of the Ge/Si nanowire devices and scale them to smaller sizes; develop their ideas for other systems, for example by creating devices with a carrier gas of electrons rather than holes; and to create large-scale assemblies of the nanowire devices for integrated systems. 

A team of University of Wisconsin-Madison engineers has created the most functional flexible transistor in the world -- and with it, a fast, simple and inexpensive fabrication process that's easily scalable to the commercial level. It's an advance that could open the door to an increasingly interconnected world, enabling manufacturers to add "smart," wireless capabilities to any number of large or small products or objects -- like wearable sensors and computers for people and animals -- that curve, bend, stretch and move. Transistors are ubiquitous building blocks of modern electronics. The UW-Madison group's advance is a twist on a two-decade-old industry standard: a BiCMOS (bipolar complementary metal oxide semiconductor) thin-film transistor, which combines two very different technologies -- and speed, high current and low power dissipation in the form of heat and wasted energy -- all on one surface. As a result, these "mixed-signal" devices (with both analog and digital capabilities) deliver both brains and brawn and are the chip of choice for many of today's portable electronic devices, including cellphones. "The industry standard is very good," says Zhenqiang (Jack) Ma, the Lynn H. Matthias Professor and Vilas Distinguished Achievement Professor in electrical and computer engineering at UW-Madison. "Now we can do the same things with our transistor -- but it can bend." Ma is a world leader in high-frequency flexible electronics. He and his collaborators described their advance in the inaugural issue of the journal Flexible Electronics. Making traditional BiCMOS flexible electronics is difficult, in part because the process takes several months and requires a multitude of delicate, high-temperature steps. Even a minor variation in temperature at any point could ruin all of the previous steps. Ma and his collaborators fabricated their flexible electronics on a single-crystal silicon nanomembrane on a single bendable piece of plastic. The secret to their success is their unique process, which eliminates many steps and slashes both the time and cost of fabricating the transistors. "In industry, they need to finish these in three months," he says. "We finished it in a week." He says his group's much simpler high-temperature process can scale to industry-level production right away. "The key is that parameters are important," he says. "One high-temperature step fixes everything -- like glue. Now, we have more powerful mixed-signal tools. Basically, the idea is for flexible electronics to expand with this. The platform is getting bigger." Ref.KY56-2SA1860KY45-EKMC1601113

Modern life will be almost unthinkable without transistors. They are the ubiquitous building blocks of all electronic devices: each computer chip contains billions of them. However, as the chips become smaller and smaller, the current 3D field-electronic transistors (FETs) are reaching their efficiency limit. A research team at the Center for Artificial Low Dimensional Electronic Systems, within the Institute for Basic Science (IBS), has developed the first 2D electronic circuit (FET) made of a single material. Published on Nature Nanotechnology, this study shows a new method to make metal and semiconductor from the same material in order to manifacture 2D FETs. Faster electronic device architectures are in the offing with the unveiling of the world’s first fully two-dimensional field-effect transistor (FET) by researchers with Lawrence Berkeley National Laboratory (Berkeley Lab). Unlike conventional FETs made from silicon, these 2D FETs suffer no performance drop-off under high voltages and provide high electron mobility, even when scaled to a monolayer in thickness.（Berkeley Lab researchers fabricated the first fully 2D field-effect transistor from layers of molybdenum disulfide, hexagonal boron nitride and graphene held together by van der Waals bonding.） Ali Javey, a faculty scientist in Berkeley Lab’s Materials Sciences Division and a UC Berkeley professor of electrical engineering and computer science, led this research in which 2D heterostructures were fabricated from layers of a transition metal dichalcogenide, hexagonal boron nitride and graphene stacked via van der Waals interactions. In simple terms, FETs can be thought as high-speed switches, composed of two metal electrodes and a semiconducting channel in between. Electrons (or holes) move from the source electrode to the drain electrode, flowing through the channel. While 3D FETs have been scaled down to nanoscale dimensions successfully, their physical limitations are starting to emerge. Short semiconductor channel lengths lead to a decrease in performance: some electrons (or holes) are able to flow between the electrodes even when they should not, causing heat and efficiency reduction. To overcome this performance degradation, transistor channels have to be made with nanometer-scale thin materials. However, even thin 3D materials are not good enough, as unpaired electrons, part of the so-called "dangling bonds" at the surface interfere with the flowing electrons, leading to scattering. FETs, so-called because an electrical signal sent through one electrode creates an electrical current throughout the device, are one of the pillars of the electronics industry, ubiquitous to computers, cell phones, tablets, pads and virtually every other widely used electronic device. All FETs are comprised of gate, source and drain electrodes connected by a channel through which a charge-carrier – either electrons or holes – flow. Mismatches between the crystal structure and atomic lattices of these individual components result in rough surfaces – often with dangling chemical bonds – that degrade charge-carrier mobility, especially at high electrical fields. Passing from thin 3D FETs to 2D FETs can overcome these problems and bring in new attractive properties. "FETs made from 2D semiconductors are free from short-channel effects because all electrons are confined in naturally atomically thin channels, free of dangling bonds at the surface," explains Ji Ho Sung, first author of the study. Moreover, single- and few-layer form of layered 2D materials have a wide range of electrical and tunable optical properties, atomic-scale thickness, mechanical flexibility and large bandgaps (1~2 eV).    Researchers produced the first 2D field-effect transistor (FET) made of a single materialThe major issue for 2D FET transistors is the existence of a large contact resistance at the interface between the 2D semiconductor and any bulk metal. To address this, the team devised a new technique to produce 2D transistors with semiconductor and metal made of the same chemical compound, molybdenum telluride (MoTe2). It is a polymorphic material, meaning that it can be used both as metal and as semiconductor. Contact resistance at the interface between the semiconductor and metallic MoTe2 is shown to be very low. Barrier height was lowered by a factor of 7, from 150meV to 22meV. IBS scientists used the chemical vapor deposition (CVD) technique to build high quality metallic or semiconducting MoTe2 crystals. The polymorphism is controlled by the temperature inside a hot-walled quartz-tube furnace filled with NaCl vapor: 710°C to obtain metal and 670°C for a semiconductor. The scientists also manufactured larger scale structures using stripes of tungsten diselenide (WSe2) alternated with tungsten ditelluride (WTe2). They first created a thin layer of semiconducting WSe2 with chemical vapor deposition, then scraped out some stripes and grew metallic WTe2 on its place. It is anticipated that in the future, it would be possible to realize an even smaller contact resistance, reaching the theoretical quantum limit, which is regarded as a major issue in the study of 2D materials, including graphene and other transition metal dichalcogenide materials. Ref.FDMT800120DCSTP160N3LL 

(Researchers made a major breakthrough in smart printed electronics. ) 2D transistors make displays so cheap that they would be literally disposable. Then wine labels could show when the contents is at the optimal drinking temperature. Researchers from AMBER and TU Delft, Netherlands have fabricated printed transistors consisting entirely of 2-dimensional nanomaterials for the first time. These 2D materials combine exciting electronic properties with the potential for low-cost production. This breakthrough could unlock the potential for applications such as food packaging that displays a digital countdown to warn you of spoiling, wine labels that alert you when your white wine is at its optimum temperature, or even a window pane that shows the day’s forecast. This discovery opens the path for industry, such as ICT and pharmaceutical, to cheaply print a host of electronic devices from solar cells to LEDs with applications from interactive smart food and drug labels to next-generation banknote security and e-passports. Printed electronic circuitry will allow consumer products to gather, process, display and transmit information: for example, milk cartons could send messages to your phone warning that the milk is about to go out-of-date. 2D nanomaterials can compete with the materials currently used for printed electronics. Compared to other materials employed in this field, they have the capability to yield more cost effective and higher performance printed devices. However, while the last decade has underlined the potential of 2D materials for a range of electronic applications, only the first steps have been taken to demonstrate their worth in printed electronics. Nanosheets for two-dimensional transistorsResearchers now show that conducting, semiconducting and insulating 2D nanomaterials can be combined together in complex devices. It was critically important to focus on printing transistors as they are the electric switches at the heart of modern computing. This work opens the way to print a whole host of devices solely from 2D nanosheets. Standard printing techniques were used to combine graphene nanosheets as the electrodes with two other nanomaterials, tungsten diselenide and boron nitride as the channel and separator (two important parts of two-dimensional transistors) to form an all-printed, all-nanosheet, working transistor. Carbon-based molecules with limitationsPrintable electronics have developed over the last thirty years based mainly on printable carbon-based molecules. While these molecules can easily be turned into printable inks, such materials are somewhat unstable and have well-known performance limitations. There have been many attempts to surpass these obstacles using alternative materials, such as carbon nanotubes or inorganic nanoparticles, but these materials have also shown limitations in either performance or in manufacturability. While the performance of printed 2D devices cannot yet compare with advanced transistors, the team believe there is a wide scope to improve performance beyond the current state-of-the-art for printed transistors. The ability to print 2D nanomaterials is based on Prof. Coleman’s (AMBER) scalable method of producing 2D nanomaterials, including graphene, boron nitride, and tungsten diselenide nanosheets, in liquids, a method he has licensed to Samsung and Thomas Swan. These nanosheets are flat nanoparticles that are a few nanometres thick but hundreds of nanometres wide. Critically, nanosheets made from different materials have electronic properties that can be conducting, insulating or semiconducting and so include all the building blocks of electronics. Liquid processing is especially advantageous in that it yields large quantities of high quality 2D materials in a form that is easy to process into inks. Prof. Coleman’s publication provides the potential to print circuitry at extremely low cost which will facilitate a range of applications from animated posters to smart labels. Ref.KY56-C4706KY56-2SA1860 

Transistors, as used in billions on every computer chip, are nowadays based on semiconductor-type materials, usually silicon. As the demands for computer chips in laptops, tablets and smartphones continue to rise, new possibilities are being sought out to fabricate them inexpensively, energy-saving and flexibly. The group led by Dr. Christian Klinke has now succeeded in producing transistors based on a completely different principle. They use metal nanoparticles which are so small that they no longer show their metallic character under current flow but exhibit an energy gap caused by the Coulomb repulsion of the electrons among one another. Via a controlling voltage, this gap can be shifted energetically and the current can thus be switched on and off as desired. In contrast to previous similar approaches, the nanoparticles are not deposited as individual structures, rendering the production very complex and the properties of the corresponding components unreliable, but, instead, they are deposited as thin films with a height of only one layer of nanoparticles. Employing this method, the electrical characteristics of the devices become adjustable and almost identical. These Coulomb transistors have three main advantages that make them interesting for commercial applications: The synthesis of metal nanoparticles by colloidal chemistry is very well controllable and scalable. It provides very small nanocrystals that can be stored in solvents and are easy to process. The Langmuir-Blodgett deposition method provides high-quality monolayered films and can also be implemented on an industrial scale. Therefore, this approach enables the use of standard lithography methods for the design of the components and the integration into electrical circuits, which renders the devices inexpensive, flexible, and industry-compatible. The resulting transistors show a switching behavior of more than 90% and function up to room temperature. As a result, inexpensive transistors and computer chips with lower power consumption are possible in the future. The research results have now been published in the scientific journal Science Advances. "Scientifically interesting is that the metal particles inherit semiconductor-like properties due to their small size. Of course, there is still a lot of research to be done, but our work shows that there are alternatives to traditional transistor concepts that can be used in the future in various fields of application," says Christian Klinke. "The devices developed in our group can not only be used as transistors, but they are also very interesting as chemical sensors because the interstices between the nanoparticles, which act as so-called tunnel barriers, react highly sensitive to chemical deposits."  Ref.KY56-MJL4302AKY56-PZTA06KY56-FZT857TA