The Kynix Blog

SummarySeveral days ago, I was facing a challenge in my lab is--what is the perfect way to power breadboard projects?Situation and SolutionActually,I used breadboards to prototype almost all of my designs and I have always had less than ideal setups.Between my bench power supply, which has banana plugs, and the many wall transformer power supplies I have around the house with 2.1 mm plugs, I just do not have any options that are breadboard friendly.Here,just see the following photos,you will know that I end up with solutions in the past,well,it's not the easiest or prettiest of ways to connect to the breadboard.It does not take more than a casual glance at the pictures above to recognize that while functional, these are not ideal solutions. In both cases, the connections are too easy to accidentally dislodge and there is a risk of a short with the second one.  There had to be a better way.Before a design could be had, it needed some requirements.  As I pondered the requirements, I came up with the following technical specifications for this little device. I wanted to be able to optionally use my bench power supply or wall transformer and that each would have a secure connection to the breadboard.  I also wanted the ability to switch it on or off and have the option to power either both rails or just one with the external supply.As I worked through the design, it became a simple but effective solution.( I am excited)At first,I created a project in Eagle CAD around the connectors I needede,and designed the board shape to match up to the standard 830 point breadboards that I use in my lab. There were a handful of other features I wanted to include such as an optional filter cap, an on/off switch, and a power status LED.   As I got designing, I decided to refine a few of the features.  Many of my projects have more than one input voltage.  To facilitate this, I added a jumper block to connect or disconnect the second power rail for projects that need a dual voltage. Electronic partsHere just let me list the material we need in this project firstly: Deltron 571-0100 : Test Sockets SINGLE PCB SOCK BLKDeltron 571-0500 : Test Sockets SINGLE PCB SOCK REDKobiconn 163-7620E-E : DC Power Connectors PCB 2.1MMFCI / Amphenol 67997-472HLF : Headers & Wire Housings 72P HDRHarwin M7581-08 : Headers & Wire Housings JUMPER SOCKET OPEN TOP REDKOA Speer MF1/2DC1501F : Metal Film Resistors – Through Hole 1.5K 1% 100PPM Kingbright WP710A10SGD : Standard LEDs – Through Hole Grn 40mcd 568nm 40 deg DiffusedPanasonic ECA-1HM100I : Aluminum Electrolytic Capacitors – Leaded 10UF 50V ELECT M RADIAL If you would like to build one following me , these parts you can find from: https://www.kynix.com Schematic and ComponentsWith the basic design framework laid out, I started researching the components needed.  I personally tend to use the online Mouser catalog to help me sort through the vast quantities of components available.  I stuck with all through-hole components to make this project easier to assemble at home.  With all the parts identified, I returned to my project in Eagle CAD and found each of the components in my component libraries.  I connected them electrically as shown in the schematic below, and double-checked the design (an often under rated step in the design process). Board LayoutWith the schematic complete, it was time to move on to the board layout. Breadboards use a standard 0.1 inch pin spacing, but when I measured the spacing between the power busses, I noticed that they were slightly different.  After some trial and error, I realized that the actual spacing between the power bus pins was 1.85 inches O.C.  With the header pins placed at this location, the board outline was adjusted to create a proper fit.  After arranging the components, I added a ground pour to the top layer to simplify routing.  The Eagle autorouter made quick work of the rest of trace routing and the resulting board design looks like this:Board Assembly and TestingI ordered a batch of these boards from my favorite purple PCB vendor (OSHPark) online and assembled them.  I couldn’t be happier with the finished product.  The fit is perfect and they snap into the power bus tightly and stay put.  This little device has gone through extensive testing as I have been using these on all of my breadboard projects ever since I got the first one assembled.  They really work wonderfully!     Article edited by: kynix 

Industrial design researchers at Brunel University London have solved two of the major challenges which prevent everyday items of clothing being turned into power sources for smartphones, tablets and other personal tech.Technology to produce super capacitor thread capable of being made into cloth has been around for some time. But until now scientists have been unable to make it provide sufficient voltage for most devices or devise a method to produce it economically outside the lab.Now patented breakthroughs made by colleagues Professors David Harrison and John Fyson, Dr Yanmeng Xu, Dr Fulian Qiu and Ruirong Zhang of Brunel's Department of Design mean thread capable of storing and supplying enough power for common devices and of being manufactured at industrial scale are a reality.Explained Prof Harrison: "Supercapacitors are already ubiquitous as back-up power in phones, PCs and tablets."They store energy without a chemical reaction so can be charged and discharged almost indefinitely. But in thread form they have never before been able to break the 1V barrier."What we have done is show we can produce a multi-layered structure with two sequential capacitive layers capable of producing up to 2V. Breaking the 1V threshold is important as in the real world we work on the voltage of common batteries – 1.5V."We also wanted to address mass production issues so developed a process to semi-automatically coat stainless steel wire the thickness of a human hair with eight separate layers."The work at Brunel is part of the EU-sponsored Powerweave programme which brings together researchers from seven countries to produce textiles which can both generate and store power.Reference:KY36-F17724102900KY36-MKP1841410254KY36-BFC246816474

SummaryFor years,people had treated the poor conductivity of organics as an unavoidable fact,and this shows that that is no always the case. Said Stephen Forrest,the Peter A. Franken Distinguished University Professor of Engineering and Paul G. Goebel Professor of Engineering at U-M, who led the research,which is  a way to coax electrons to travel much further than was previously thought possible in the materials often used for organic solar cells and other organic semiconductors under the condition of pushing cheap,ubiquitous solar power closer to reality. The fatal weakness of organic material may adjust its conductivityUnlike the inorganic solar cells widely used today, organics can be made of inexpensive, flexible carbon-based materials like plastic. Manufacturers could churn out rolls of them in a variety of colors and configurations, to be laminated unobtrusively into almost any surface. Organics’ notoriously poor conductivity, however, has slowed research. Forrest believes this discovery could change the game.  The team showed that a thin layer of fullerene molecules—the curious round carbon molecules also called Buckyballs—can enable electrons to travel up to several centimeters from the point where theyre knocked loose by a photon. That’s a dramatic increase; in today's organic cells, electrons can travel only a few hundred nanometers or less. But organic materials have much looser bonds between individual molecules, which can trap electrons. This has long been an Achilles’ heel of organics, but the new discovery shows that it may be possible to tweak their conductive properties for specific applications. The ability to make electrons move more freely in organic semiconductors The ability to make electrons move more freely in organic semiconductors could have far-reaching implications. For example, the surface of today's organic solar cells must be covered with a conductive electrode that collects electrons at the point where they’re initially generated. But freely moving electrons can be collected far away from their point of origination. This could enable manufacturers to shrink the conductive electrode into an invisible grid, paving the way for transparent cells that could be used on windows and other surfaces. “This discovery essentially gives us a new knob to turn as we design organic solar cells and other organic semiconductor devices,” said Quinn Burlingame, a U-M electrical engineering and computer science graduate researcher and author on the study. “The possibility of long-range electron transport opens up a lot of new possibilities in device architecture.” Burlingame says that the initial discovery of the phenomenon came as something of an accident as the team was experimenting with organic solar cell architecture in hopes of boosting efficiency. Using a common technique called vacuum thermal evaporation, they layered in a thin film of C60 fullerenes—each made of 60 carbon atoms—on top of an organic cell's power-producing layer, where the photons from sunlight knock electrons loose from their associated molecules. On top of the fullerenes, they put another layer to prevent the electrons from escaping. They discovered something they’d never seen before in an organic—electrons were skittering unfettered through the material, even outside the power-generating area of the cell. Through months of experimentation, they determined that the fullerene layer formed what's known as an energy well—a low-energy area that prevents the negatively charged electrons from recombining with the positive charges left behind in the power-producing layer.“You can imagine an energy well as sort of a canyon—electrons fall into it and can’t get back out,” said Caleb Cobourn, a graduate researcher in the U-M Department of Physics and an author on the study. “So they continue to move freely in the fullerene layer instead of recombining in the power-producing layer, as they normally would. It's like a massive antenna that can collect an electron charge from anywhere in the device.”Forrest cautions that widespread use of the discovery in applications like solar cells is theoretical at this point. But, he is excited by the discovery’s larger implications for understanding and exploiting the properties of organic semiconductors. “I believe that ubiquitous solar power is the key to powering our constantly warming and increasingly crowded planet, and that means putting solar cells on everyday objects like building facades and windows,” Forrest said. “Technology like this could help us produce power in a way that’s inexpensive and nearly invisible.” The study is titled “Centimeter-Scale Electron Diffusion in Photoactive Organic Heterostructures.” The research was supported by the U.S. Department of Energy SunShot Program and by the Air Force Office of Scientific Research.    Article from University of MichiganArticle edited by kynix 

(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 

This article will introduce to you how RFID sensors are applied to detecting food quality and monitoring food safety.   Catalog I. Brief Introduction II. General Principles of Design and Operation of RFID Food Sensors III. Example of Applications FAQ I. Brief Introduction   Radio frequency identification (RFID) sensors are finding their diverse applications when an unobtrusive sensor form factor, battery-free design, and minimal sensor cost are the top three requirements for a new sensor. Examples of diverse applications include pharmaceutical, warehousing, agricultural, industrial, food safety, and security.    Benefits of RFID sensors for food quality and safety, as compared to tethered sensors, include the non-obtrusive nature of their installations, higher nodal densities, and lower installation costs without the need for extensive wiring.   In addition, a significant advantage of RFID and other electronic sensors over optical sensors is in the ability to perform measurements through non-transparent packaging.   There are several developed battery-free wireless sensing technologies based on magnetoelastic,16 thickness-shear modes, surface acoustic wave, magnetic acoustic resonance, and resonant LCR (inductor-capacitor-resistor) transducers. Several approaches for battery-free RFID sensing have been explored, e.g. based on chipless RFID sensors.   We recently developed a methodology to implement passive RFID tags for physical, chemical, and biological sensing. In our RFID sensing approach, the resonance impedance spectrum of the sensor antenna is measured and further correlated with the chemical, biological, or physical properties of the environment. This correlation is performed using the multivariable response of the RFID sensor computed from the measured impedance spectrum.   The complementary driving forces in successful sensor development are innovative ideas and the market size for new sensors. The market size is often but not always is supported by the regulatory requirements. If both driving forces are strong, the sensor development moves from its initial proof-of-concept technology readiness level to the commercialization of the sensor technology.   The sizes of markets for food safety testing products ($0.25 B) and pathogen detecting sensors ($0.5 B) and provide exciting opportunities for the development of new sensing technologies for food quality and safety.   Intelligent labeling of food products to indicate and report their freshness and other conditions is one of the important possible applications of the developed RFID sensors.   Unlike other food freshness monitoring approaches that require a thin-film battery for operation of an RFID sensor and fabrication of custom-made sensors, our developed passive RFID sensing approach combines advantages of both battery-free and cost-effective sensor design and offers response selectivity that is impossible to achieve with other individual sensors.   In this review, we summarize the result of the development of RFID sensors for food quality and safety. In these sensors, the electric field generated in the RFID sensor antenna extends out from the plane of the RFID sensor and is affected by the ambient environment providing the opportunity for sensing.   This environment may be in the form of a food sample within the electric field of the sensing region or a sensing film deposited onto the sensor antenna. Examples of applications include monitoring of freshness of milk, the freshness of fish, and bacterial growth.   II. General Principles of Design and Operation of RFID Food Sensors     (Figure 1) Operation principle of developed passive RFID sensors. (A) Sensor equivalent circuit described by the inductance LA, capacitance CA, and resistance RA of the sensing antenna coil, capacitance CS and resistance RS of the sensing region, and capacitance ...   In order to assess the broad applicability of the developed sensors for food safety applications, it is critical to understand the general principles of their design and operation (see Figure 1).   The equivalent circuit of the developed sensors forms an inductor-capacitor-resistor (LCR) circuit and is described by the inductance LA, capacitance CA, and resistance RA of the sensing antenna coil, capacitance CS and resistance RS of the sensing region, and capacitance CC and resistance RC of the integrated circuit (IC) chip (see Figure 1A).   Reading and writing of digital information into the RFID sensor and measurement of the impedance of the RFID sensor antenna are performed via mutual inductance coupling between the RFID sensor antenna and the pickup coil of a digital/analog sensor reader.   Impedance spectra Ž(f) of the sensor are measured using a laboratory or a portable network analyzer component and digital data from an IC chip is measured with a digital RFID reader component29 of our custom sensor reader.   Digital data include sensor calibrations, food manufacturing data, end-user data, etc. The network analyzers are used to scan the frequencies over the range of interest (typically centered at 13 MHz with a scan range of ~10 MHz).   The electric field generated in the RFID sensor antenna extends out from the plane of the RFID sensor (Figure 1B) and is affected by the ambient environment providing the opportunity for sensing. This environment may be in the form of a food sample within the electric field of the sensing region or a sensing film deposited onto the sensor antenna.   In both cases, the impedance of the antenna circuit Ž(f) is modulated through the changes in capacitance CS and resistance RS of the sensing region. This sensing region can be in the form of a full antenna or a complementary region in contact with the antenna.32 Numerous types of sensing materials applicable for food quality sensing were recently analyzed.   To achieve accurate and precise measurements using our sensors, we measure the real Zre(f) and imaginary Zim(f) parts of the impedance spectra Ž(f) and calculate several spectral parameters.   A schematic representation of the real Zre(f) and imaginary Zim(f) parts of the impedance spectrum Ž(f) of the sensor without possible effects from a pickup coil is illustrated in Figure 1C. Several calculated spectral parameters include the frequency position Fp and magnitude Zp of Zre(f) and the resonant F1 and antiresonant F2 frequencies of Zim(f).   Additional parameters can also be calculated (impedance magnitudes Z1 and Z2 at F1 and F2 frequencies, respectively, zero-reactance frequency, quality factor, etc). From the measured parameters, resistance, capacitance, and other parameters of the resonant antenna can be also determined. Figure 2 shows examples of RFID sensors applied in our studies for food quality and safety.       (Figure 2) Examples of employed RFID sensors based on (A) Texas Instruments RFID tag, (B) Avery Dennison RFID tag, (C) TagSys RFID tag.   Uncontrolled temperature fluctuations produce independent effects on the different components of the equivalent circuit. These independent effects are correlated with the spectral features of the resonance impedance spectra and are resolved by the multivariable response of the sensor.   For scenarios when the food is irradiated by ionizing radiation as a food safety measure to destroy bacteria, pathogens, and pests,39,40 conventional RFID IC memory chips do not survive the applied radiation dose that can be up to 30 kGy.   We have developed a technical solution to solve this problem where an IC chip is based on the Ferroelectric Random Access Memory (FRAM) technology and provides reliable gamma-resistant RFID tags and sensors.   The FRAM memory chips have 2000 bytes of user memory (MB89R118A, Fujitsu Microelectronics Ltd, Japan)42 and are made using a standard RF signal modulation circuitry fabricated using a 0.35-μm complementary metal-oxide-semiconductor (CMOS) process and a non-volatile FRAM memory.43 A photo of this IC chip is shown in Figure 3A while one of our RFID sensors with such an IC chip is shown in Figure 3B.   (Figure 3) Photographs of (A) FRAM IC memory chip MB89R118A and (B) Developed RFID sensor for gamma-sterilizable applications. Sensor diameter = 10 mm. III. Example of Applications       · Monitoring of milk freshness     · Monitoring of fish condition     · Direct monitoring of bacteria growth FAQ   1. What is RFID used for? Radio Frequency Identification (RFID) is the wireless non-contact use of radio frequency waves to transfer data. Tagging items with RFID tags allows users to automatically and uniquely identify and track inventory and assets.   2. What is RFID and how it works? RFID is a method of data collection that involves automatically identifying objects through low-power radio waves. Data is sent and received with a system consisting of RFID tags, an antenna, an RFID reader, and a transceiver.   3. What RFID means? Radio Frequency Identification (RFID) refers to a wireless system comprised of two components: tags and readers. The reader is a device that has one or more antennas that emit radio waves and receive signals back from the RFID tag.   4. Is RFID harmful to human? It is a non-ionizing type of radiation, but some researches show that it could have a negative impact on the human body in a long-term period [11, 12]. So, for the safety reasons, manufacturers of the RFID systems have limited the range of the RFID antennas used in their systems.   5. Is RFID tag and FASTag same? FASTag is a device that employs Radio Frequency Identification (RFID) technology for making toll payments directly while the vehicle is in motion. FASTag (RFID Tag) is affixed on the windscreen of the vehicle and enables a customer to make the toll payments directly from the account which is linked to FASTag.   6.What is RFID and its advantages? RFID technology automates data collection and vastly reduces human effort and error. RFID supports tag reading with no line-of-sight or item-by-item scans required. RFID readers can read multiple RFID tags simultaneously, offering increases in efficiency.   7. Why is RFID bad? Some negative effects are that its deadly, if RFID tags combine with static electricity you can die. Another negative effect is that the government is slowly taking away surviving resources and giving ultimatums, such as if you don't get the RFID tracking chip your public assistance will be terminated.   8.What are the disadvantages of RFID? a. Materials like metal & liquid can impact signal. b. Sometimes not as accurate or reliable as barcode scanners. c. Cost – RFID readers can be 10x more expensive than barcode readers. d. Implementation can be difficult & time consuming.   9.How do I charge my RFID FASTag? In order to recharge your FASTag sticker, just hit the Add Money option in your Paytm app. FASTag will automatically reserve some amount from your wallet, which can be used at toll plazas later. Do note that FASTag can be used only after 20 mins of adding money to the Paytm Wallet.   10. Can I use existing RFID for FASTag? If a vehicle already has an RFID tag, it might already be activated. When you buy the vehicle, RFID tag payment was also done. It might also have a minimum balance of INR 100 or 200 as is required by the bank. You can recharge it with your Customer ID or Wallet ID of FASTag.   11. How does RFID work without power? Passive RFID tags have no power of their own and are powered by the radio frequency energy transmitted from RFID readers/antennas. The signal sent by the reader and antenna is used to power on the tag and reflect the energy back to the reader.   12. What are the types of RFID tags? RFID tags can be grouped into three categories based on the range of frequencies they use to communicate data: low frequency (LF), high frequency (HF) and ultra-high frequency (UHF). Generally speaking, the lower the frequency of the RFID system, the shorter the read range and slower the data read rate.   13.How do I know if I have an RFID chip? The best way to check for an implant would be to have an X-ray performed. RFID transponders have metal antennas that would show up in an X-ray. You could also look for a scar on the skin. Because the needle used to inject the transponder under the skin would be quite large, it would leave a small but noticeable scar.   14. Does RFID require power? Active RFID tags possess their own power source – an internal battery that enables them to have extremely long read ranges as well as large memory banks. Typically, active RFID tags are powered by a battery that will last between 3 - 5 years, but when the battery fails, the active tag will need to be replaced.   15. What is the difference between a QR code and RFID? QR codes must always be “read-only”, whereas RFID tags can be “read-write”, depending on the radio frequency that's being used. ... So, not only are RFID tags futuristic and have more uses than QR tags, they also have many more applications. The read range is far superior for an RFID tag.   Ref. KY45-R300-F35-M14-C KY78-2867704

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