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A NIMS research group led by Jiangwei Liu (independent scientist, Research Center for Functional Materials) and Yasuo Koide (coordinating director in the Research Network and Facility Services Division) has succeeded for the first time in the world in developing logic circuits equipped with diamond-based MOSFETs (metal-oxide-semiconductor field-effect-transistors) at two different operation modes. This achievement is a first step toward the development of diamond integrated circuits operational under extreme environments.Diamond has high carrier mobility, a high breakdown electric field and high thermal conductivity. Therefore, it is a promising material to be used in the development of current switches and integrated circuits that are required to operate stably at high-temperature, high-frequency, and high-power. However, it had been difficult to enable diamond-based MOSFETs to control the polarity of the threshold voltage, and to fabricate MOSFETs of two different modes―a depletion mode (D mode) and an enhancement mode (E mode)―on the same substrate. The research group has successfully developed a logic circuit equipped with both D- and E-mode diamond MOSFETs after making a breakthrough by fabricating them on the same substrate using a threshold control technique developed by the group. The research group identified the electronic structure in the interface between various oxides and hydrogenated diamond using photoelectron spectroscopy in 2012. The research group then succeeded in developing a diamond MOS (metal-oxide-semiconductor) capacitor with very low leakage current density and an E-mode hydrogenated diamond-based MOSFET in 2013 after going through many difficulties. The group then prototyped logic circuits by combining diamond-based MOSFETs with load resistors in 2014. Finally, the group developed techniques to control D- and E-mode characteristics of diamond-based MOSFETs and identified the control mechanism in 2015. A series of these R&D accomplishments were introduced in AIP publishing news by the American Institute of Physics. These previous efforts led to the success made in this research project. The logic circuits with diamond-based transistors are promising devices to be used in the development of digital integrated circuits that are required to stably operate under extreme environments such as high-temperature as well as exposure to radiation and cosmic rays. This research was conducted in conjunction with the following projects: Leading Initiative for Excellent Young Researchers (Jiangwei Liu, representative), under the sponsorship of the MEXT Human Resource Development Program for Science and Technology; "Development of new functional diamond electronic devices using a large amount of polarized charges" (Yasuo Koide, principal investigator), under the category of Grant-in-Aid for Scientific Research (A) sponsored by the MEXT Grants-in-Aid for Scientific Research; and "Fabrication of high-current output fin-type diamond field-effect transistors" (Jiangwei Liu, principal investigator), under the category of Grant-in-Aid for Young Scientists (B) sponsored by the MEXT Grants-in-Aid for Scientific Research. Device fabrication was supported by the NIMS Nanofabrication Platform, established under the MEXT Nanotechnology Platform Japan program. Ref.DMN63D0LT-7DMN5L06VK-7

Ion Transistors for the transport of both positive and negative ions, as well as biomolecules had been previously developed by a group of Organic Electronics research team at Linköping University. Now Tybrandt has now succeed in developing circuits using these Transistors similar to traditional silicon electronics. In essence of this technology we can build computer chips that can directly interface with our body cells.The major advantage of chemical circuit is that the charge carrier consists of chemical substances with various functions and this gives us new opportunities to regulate and control signal paths of Human Body Cells.In a conventional transistor there are three terminals Gate, Source and Drain. When signal is applied to Gate terminal, electrons flow from Source to Drain. Electrons are the charge carrier in conventional transistor, but in the new Ion Transistor the ionic neurotransmitter acetylcholine is the charge carrier. NAND gates and Inverters can be created using these Ion transistors, which means that it can be used to implement any logic function.Magnus Berggren, Professor of Organic Electronics and leader of the research group says that, it can be used to send signals to muscle synapses when our muscle signalling system may not works for some reasons and our chips works with common signalling substances such as acetylcholine.The research in Ion Transistors which can control and transport ions and charged biomolecules was begun before 3 years by Berggren (professor in Organic Electronics at the Department of Science and Technology at Linköping University) and Tybrandt (a doctoral student). Researchers at Karolinska Institute then used this Transistors to control the delivery of the signalling substance acetylcholine to individual cells. It hopes that it can restore the lost movement of paralysed peoples.Mr. Tybrandt in conjunction with Robert Forchheimer (Professor of Information Coding at LiU) has taken the next steps by developing chemical chips which contains logic gates, that allows the construction of all logic functions.Ref:KY56-C4706KY56-KSC5024RTUKY56-MJL21193G

(This is a high precision control of printed electronics.)Printed electronic transistor circuits and displays, in which the colour of individual pixels can be changed, are two of many applications of ground-breaking research at the Laboratory of Organic Electronics, Linköping University. New groundbreaking results on these topics have been published in the scientific journal Science Advances. The researchers in organic electronics have a favourite material to work with: the conducting polymer PEDOT:PSS, which conducts both electrons and ions. Displays and transistors manufactured from this polymer have many advantages, which include that they are simple and cheap to manufacture, and the material itself is non-hazardous. It has, however, been difficult to create devices that switch rapidly at a specific voltage, known as the "threshold voltage." This gives that it has, so far, been difficult to control the current state of the transistors or the color state of the displays in a precise manner. "The lack of any threshold in the redox-switching characteristics of PEDOT:PSS hampers bistability and rectification, characteristics that would allow for passive matrix addressing in display or memory functionality" says Simone Fabiano, senior lecturer at the Laboratory of Organic Electronics, LOE, who is the principal author of the article in Science Advances, together with Negar Sani from the research institute RISE Acreo. More than five years ago a wild idea arose at the Laboratory of Organic Electronics: could you solve this problem by combining electrochemistry with ferroelectricity? Ferroelectric materials consist of dipoles. One end of a dipole has a positive charge and the other a negative charge, and these "ferroelectric" dipoles rotate when they are exposed to an electric field beyond a specific threshold. Head of the laboratory Professor Magnus Berggren couldn't let this idea rest, and when he was awarded a research grant from the Knut and Alice Wallenberg Foundation in December 2012 to use freely, this was one of the high-risk projects he chose to invest in. "We called the research then breakneck research, and here is a result. Our demonstration proves that truly leading research typically take a long time and require considerable patience. Simone Fabiano has done tremendous work here, and refused to give up when others have doubted," says Magnus Berggren. After many years of tenacious experiments, Simone Fabiano and his colleagues at the Laboratory of Organic Electronics have managed to apply a thin layer of a ferroelectric material onto one electrode in organic electrochemical devices and circuits. "The thickness of the layer determines the voltage at which the circuit switches or the display changes colour. Transistors are no longer required in the displays: we can control them pixel-by-pixel simply through a thin ferroelectric layer on the electrode," says Simone Fabiano. The LOE research group shows in the article that "ferroelectrochemistry," the combination of ferroelectricity and electrochemistry, can be used in displays in the field of printed electronics and in organic transistors. The scientists envisage, however, many other areas of application. "Ferroelectrochemical components can easily be integrated into memory matrices and into bioelectronic applications, just to give a couple of examples," says Simone Fabiano. The technology is now protected by patents. "The field of ferroelectrochemistry doesn't actually exist, but we have achieved success using this combination," Magnus Berggren concludes. Ref.KY56-2SA1987KY56-KSC5024RTUKY56-FJI5603D 

At this week's IEEE IEDM conference, world-leading research and innovation hub for nano-electronics and digital technology, imec, reported for the first time the CMOS integration of vertically stacked gate-all-around (GAA) silicon nanowire MOSFETs. Key in the integration scheme is a dual-work-function metal gate enabling matched threshold voltages for the n- and p-type devices. Also, the impact of the new architecture on intrinsic ESD performance was studied, and an ESD protection diode is proposed. These breakthrough results advance the development of GAA nanowire MOSFETs, which promise to succeed FinFETs in future technology nodes. GAA nanowire transistors are promising candidates to succeed FinFETs in 7nm and beyond technology nodes. They offer optimal electrostatic control, thereby enabling ultimate CMOS device scaling. In a horizontal configuration, they are a natural extension of today's mainstream FinFET technology. In this configuration, the drive current per footprint can be maximized by vertically stacking multiple horizontal nanowires. Earlier this year, imec scientists demonstrated GAA FETs based on vertically stacked 8nm diameter Si nanowires. These devices showed excellent electrostatic control, but were fabricated for n- and p-FETs separately.Imec now reports on the CMOS integration of vertically stacked GAA Si nanowire MOSFETs, with matched threshold voltages for n- and p-type devices. Key in the integration scheme is the implementation of dual-work-function metal gates to set the threshold voltages of the n- and p-FETs independently. In this process step, p-type work function metal (PWFM) is deposited in the gate trenches of all devices, followed by selectively etching the PWFM down to the HfO2 from the n-FETs and subsequent deposition of the n-type work function metal. The observation of matched threshold voltages (VT,SAT = 0.35V) for nMOS and pMOS devices validates the dual-work-function metal integration scheme.The impact of this new device architecture on the intrinsic ESD performance was investigated as well. Two different ESD protection diodes have been proposed, i.e. a gate-structure defined diode (gated diode) and a shallow-trench isolation defined diode (STI diode). The STI diode was the better ESD protection device, showing an excellent ratio of failure current (It2) over parasitic capacitance (C). Measurements and TCAD simulations also prove that the ESD performance in GAA nanowire based diodes is maintained in comparison to bulk FinFET diodes."GAA nanowire transistors enable ultimate CMOS device scaling, with low degree of added complexity compared to alternative scaling scenarios," stated Dan Mocuta, Director Logic Device and Integration at imec. The proposed integration scheme for Si GAA CMOS technology and the results on ESD protection are important achievements towards realizing these 7nm and beyond technology nodes. Future work will focus, among others, on further optimizing individual process steps, for example through the co-optimization of the junction and nanowire formation."Ref:KY56-2SA1987KY56-KSC5024RTUKY56-MJL4302A          

It's hardly a character flaw, but organic transistors—the kind envisioned for a host of flexible electronics devices—behave less than ideally, or at least not up to the standards set by their rigid, predictable silicon counterparts. When unrecognized, a new study finds, this disparity can lead to gross overestimates of charge-carrier mobility, a property key to the performance of electronic devices.If measurements fail to account for these divergent behaviors in so-called "organic field-effect transistors" (OFETs), the resulting estimates of how fast electrons or other charge carriers travel in the devices may be more than 10 times too high, report researchers from the National Institute of Standards and Technology (NIST), Wake Forest University and Penn State University. The team's measurements implicate an overlooked source of electrical resistance as the root of inaccuracies that can inflate estimates of organic semiconductor performance.Already used in light-emitting diodes, or LEDs, electrically conductive polymers and small molecules are being groomed for applications in flexible displays, flat-panel TVs, sensors, "smart" textiles, solar cells and "Internet of Things" applications. Besides flexibility, a key selling point is that the organic devices—sometimes called "plastic electronics"—can be manufactured in large volumes and far more inexpensively than today's ubiquitous silicon-based devices.A key sticking point, however, is the challenge of achieving the high levels of charge-carrier mobility that these applications require. In the semiconductor arena, the general rule is that higher mobility is always better, enabling faster, more responsive devices. So chemists have set out to hurry electrons along. Working from a large palette of organic materials, they have been searching for chemicals—alone or in combination—that will up the speed limit in their experimental devices.Just as for silicon semiconductors, assessments of performance require measurements of current and voltage. In the basic transistor design, a source electrode injects charge into the transistor channel leading to a drain electrode. In between sits a gate electrode that regulates the current in the channel by applying voltage, functioning much like a valve.Typically, measurements are analyzed according to a longstanding theory for silicon field-effect transistors. Plug in the current and voltage values and the theory can be used to predict properties that determine how well the transistor will perform in a circuit.Results are rendered as a series of "transfer curves." Of particular interest in the new study are curves showing how the drain current changes in response to a change in the gate electrode voltage. For devices with ideal behavior, this relationship provides a good measure of how fast charge carriers move through the channel to the drain."Organic semiconductors are more prone to non-ideal behavior because the relatively weak intermolecular interactions that make them attractive for low-temperature processing also limit the ability to engineer efficient contacts as one would for state-of-the-art silicon devices," says electrical engineer David Gundlach, who leads NIST's Thin Film Electronics Project. "Since there are so many different organic materials under investigation for electronics applications, we decided to step back and do a measurement check on the conventional wisdom."Using what Gundlach describes as the semiconductor industry's "workhorse" measurement methods, the team scrutinized an OFET made of single-crystal rubrene, an organic semiconductor with a molecule shaped a bit like a microscale insect. Their measurements revealed that electrical resistance at the source electrode—the contact point where current is injected into the OFET— significantly influences the subsequent flow of electrons in the transistor channel, and hence the mobility.In effect, contact resistance at the source electrode creates the equivalent of a second valve that controls the entry of current into the transistor channel. Unaccounted for in the standard theory, this valve can overwhelm the gate—the de facto¬ regulator between the source and drain in a silicon semiconductor transistor—and become the dominant influence on transistor behavior.At low gate voltages, this contact resistance at the source can overwhelm device operation. Consequently, model-based estimates of charge-carrier mobility in organic semiconductors may be more than 10 times higher than the actual value, the research team reports.Hardly ideal behavior, but the aim of the study, the researchers write, is to improve "understanding of the source of the non-ideal behavior and its impact on extracted figures of merit," especially charge-carrier mobility. This knowledge, they add, can inform efforts to develop accurate, comprehensive measurement methods for benchmarking organic semiconductor performance, as well as guide efforts to optimize contact interfaces.Reference:2SA1987C4706FJA4213RTU 

Together with his research team, Lars-Erik Wernersson, professor of nanoelectronics at Lund University in Sweden, has developed a technology for smarter transistors which could be used in electronics that operate on low energy, such as sensors for the IoT. Using the new transistors on a large scale could save enormous amounts of energy. Transistors are the smallest building blocks in electronics - a kind of switch.When the amount of energy required to switch the transistors on or off is reduced, major savings can be made overall. Transistors with low-energy consumption are expected to be highly significant for applications within the IoT.With the help of nanotechnology, the material and architecture in the transistors have been optimised so that they consume only a third of the energy required with the current technology when operating at low voltages. They can be used in digital circuits, various sensors and communication.“We have been able to operate the transistors under what is known as the fundamental thermionic limit, which reduces energy consumption. The next step is to continue to study the physics and to understand the components better, so that they can be further optimised. We also want to find new ways of transferring the technology to industry,” says Lars-Erik Wernersson.The researchers’ findings will probably have moved into production processes within five to ten years. According to Lars-Erik Wernersson, the extent of the energy savings will depend on the quality of the components which can be produced in industry.“The dream scenario is that all data servers will consume less energy thanks to the technology we use. In that case, the savings in one year would be comparable to all the energy consumed in Great Britain during the same period.”When his researcher colleagues recently reported data from an experiment conducted within the EU-funded E2SWITCH project, Lars-Erik Wernersson, along with the doctoral students who carried out the test, realised that these were ground-breaking results:“We have repeated the tests many times and succeeded in demonstrating that the performance with this new, energy-saving technology is not only satisfactory, but even better than that based on the traditional technologies.”According to Lars-Erik Wernersson, the new technology is a complement and one of several technologies which can be used to create more energy-efficient transistors – and different types of applications require different solutions.“We are very happy to have found something that many people have been searching for. We have shown that the transistors have high performance and that it is possible to reduce energy consumption. And now we can continue to add pieces to the puzzle,” concludes Lars-Erik Wernersson.Reference:2SA1987C47062sb1647