Electronics news and discussion thread

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Electronics news and discussion thread

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First organic bipolar transistor developed
https://techxplore.com/news/2022-06-bip ... istor.html
by Dresden University of Technology
The invention of the transistor in 1947 by Shockley, Bardeen and Brattain at Bell Laboratories ushered in the age of microelectronics and revolutionized our lives. First, so-called bipolar transistors were invented, in which negative and positive charge carriers contribute to the current transport; unipolar field effect transistors were only added later. The increasing performance due to the scaling of silicon electronics in the nanometer range has immensely accelerated the processing of data. However, this very rigid technology is less suitable for new types of flexible electronic components, such as rollable TV displays or medical applications.

For such applications, transistors made of organic material, or carbon-based semiconductors, have come into focus in recent years. Organic field effect transistors were introduced as early as 1986, but their performance still lags far behind silicon components.

A research group led by Prof. Karl Leo and Dr. Hans Kleemann at the TU Dresden has now succeeded for the first time in demonstrating an organic, highly efficient bipolar transistor. Crucial to this was the use of highly ordered thin organic layers. This new technology is many times faster than previous organic transistors, and for the first time the components have reached operating frequencies in the gigahertz range (i.e., more than a billion switching operations per second).
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Research allows for 3D printing of 'organic electronics'
https://techxplore.com/news/2022-06-3d-electronics.html
by University of Houston
When looking at the future of production of micro-scale organic electronics, Mohammad Reza Abidian—associate professor of Biomedical Engineering at the University of Houston Cullen College of Engineering—sees their potential for use in flexible electronics and bioelectronics, via multiphoton 3D printers.

The newest paper from his research group examines the possibility of that technology. "Multiphoton Lithography of Organic Semiconductor Devices for 3D Printing of Flexible Electronic Circuits, Biosensors, and Bioelectronics" was published online in Advanced Materials.

Over the past few years, 3D printing of electronics have become a promising technology due to their potential applications in emerging fields such as nanoelectronics and nanophotonics. Among 3D microfabrication technologies, multiphoton lithography (MPL) is considered the state-of-the-art amongst the microfabrication methods with true 3D fabrication capability, excellent level of spatial and temporal control, and the versatility of photosensitive materials mostly composed of acrylate-based polymers/monomers or epoxy-based photoresists.
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Electrospinning promises major improvements in wearable technology

by American Institute of Physics
https://techxplore.com/news/2022-06-ele ... ology.html
Wearable technology has exploded in recent years. Spurred by advances in flexible sensors, transistors, energy storage, and harvesting devices, wearables encompass miniaturized electronic devices worn directly on the human skin for sensing a range of biophysical and biochemical signals or, as with smart watches, for providing convenient human-machine interfaces.

Engineering wearables for optimal skin conformity, breathability, and biocompatibility without compromising the tunability of their mechanical, electrical, and chemical properties is no small task. The emergence of electrospinning—the fabrication of nanofibers with tunable properties from a polymer base—is an exciting development in the field.

In APL Bioengineering, researchers from Tufts University examined some of the latest advances in wearable electronic devices and systems being developed using electrospinning.

"We show how the scientific community has realized many remarkable things using electrospun nanomaterials," said author Sameer Sonkusale. "They have applied them for physical activity monitoring, motion tracking, measuring biopotentials, chemical and biological sensing, and even batteries, transistors, and antennas, among others."

Sonkusale and his colleagues showcase the many advantages electrospun materials have over conventional bulk materials.
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New type of semiconductor may advance low-energy electronics
https://techxplore.com/news/2022-07-sem ... onics.html
by Jamie Oberdick, Pennsylvania State University
A research partnership between Penn State and the Massachusetts Institute of Technology (MIT) could enable an improved method to make a new type of semiconductor that is a few atoms thin and interacts with light in an unusual way. This new semiconductor could lead to new computing and communications technologies that use lower amounts of energy than current electronics.

The new type of semiconductor, tin selenide (SnSe), would be useful for developing a new type of electronics known as "photonics" that use particles of light, or photons, to store, manipulate and transmit information. Traditional electronics use electrons to do this, while photonics use photons. Tin selenide is a binary compound consisting of tin and selenium in a 1:1 ratio.

The material has a peculiar interaction with light that gives it great potential for use in electronics.

"It can be described as a material that has two different colors, meaning that depending on the orientation that you look at it, you will observe a different color," said Wouter Mortelmans, a postdoctoral associate in the Department of Materials Science and Engineering at MIT, and lead author of the study. "This peculiar optical property could be very useful to compute, store, or transmit information using light."

To make use of these orientation-dependent properties, it is very important that the fabrication of the material is done with atomic-precision control, said Mortelmans. The dependence of color on material orientation would enable faster and easier inspection of material quality.

"We need a reliable way to make the material, to manufacture devices to spec, without worrying about random, natural variations," said Rafael Jaramillo, Thomas Lord Associate Professor of Materials Science and Engineering at MIT and senior author of the study published in ACS Nano.
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Have researchers found the best semiconductor of them all?

by David L. Chandler, Massachusetts Institute of Technology
https://techxplore.com/news/2022-07-semiconductor.html
Silicon is one of the most abundant elements on Earth, and in its pure form the material has become the foundation of much of modern technology, from solar cells to computer chips. But silicon's properties as a semiconductor are far from ideal.

For one thing, although silicon lets electrons whizz through its structure easily, it is much less accommodating to "holes"—electrons' positively charged counterparts—and harnessing both is important for some kinds of chips. What's more, silicon is not very good at conducting heat, which is why overheating issues and expensive cooling systems are common in computers.

Now, a team of researchers at MIT, the University of Houston, and other institutions has carried out experiments showing that a material known as cubic boron arsenide overcomes both of these limitations. It provides high mobility to both electrons and holes, and has excellent thermal conductivity. It is, the researchers say, the best semiconductor material ever found, and maybe the best possible one.

So far, cubic boron arsenide has only been made and tested in small, lab-scale batches that are not uniform. The researchers had to use special methods originally developed by former MIT postdoc Bai Song to test small regions within the material. More work will be needed to determine whether cubic boron arsenide can be made in a practical, economical form, much less replace the ubiquitous silicon. But even in the near future, the material could find some uses where its unique properties would make a significant difference, the researchers say.

The findings are reported in the journal Science, in a paper by MIT postdoc Jungwoo Shin and MIT professor of mechanical engineering Gang Chen; Zhifeng Ren at the University of Houston; and 14 others at MIT, the University of Houston, the University of Texas at Austin, and Boston College.

Earlier research, including work by David Broido, who is a co-author of the new paper, had theoretically predicted that the material would have high thermal conductivity; subsequent work proved that prediction experimentally. This latest work completes the analysis by confirming experimentally a prediction made by Chen's group back in 2018: that cubic boron arsenide would also have very high mobility for both electrons and holes, "which makes this material really unique," says Chen.
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An ultrafast and highly performing nonlinear splitter based on lithium niobate
https://techxplore.com/news/2022-08-ult ... based.html
by Ingrid Fadelli , Tech Xplore
Optics, technologies that leverage the behavior and properties of light, are the basis of many existing technological tools, most notably fiber communication systems that enable long- and short-distance high-speed communication between devices. Optical signals have a high information capacity and can be transmitted across longer distances.

Researchers at California Institute of Technology have recently developed a new device that could help to overcome some of the limitations of existing optical systems. This device, introduced in a paper published in Nature Photonics, is a lithium niobate-based device that can switch ultrashort light pulses at an extremely low optical pulse energy of tens of femtojoules.
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Print, recycle, repeat: Scientists demonstrate a biodegradable printed circuit
https://techxplore.com/news/2022-08-rec ... rcuit.html
by Theresa Duque, Lawrence Berkeley National Laboratory
According to the United Nations, less than a quarter of all U.S. electronic waste gets recycled. In 2021 alone, global e-waste surged at 57.5 million tons, and only 17.4% of that was recycled.

Some experts predict that our e-waste problem will only get worse over time, because most electronics on the market today are designed for portability, not recyclability. Tablets and readers, for example, are assembled by gluing circuits, chips, and hard drives to thin layers of plastic, which must be melted to extract precious metals like copper and gold. Burning plastic releases toxic gases into the atmosphere, and electronics wasting away in landfill often contain harmful materials like mercury, lead, and beryllium.

But now, a team of researchers from the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley have developed a potential solution: a fully recyclable and biodegradable printed circuit. The researchers, who reported the new device in the journal Advanced Materials, say that the advance could divert wearable devices and other flexible electronics from landfill, and mitigate the health and environmental hazards posed by heavy metal waste.
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imple technique ushers in long-sought class of semiconductors

by Osaka University
https://phys.org/news/2022-08-simple-te ... class.html
Breakthroughs in modern microelectronics depend on understanding and manipulating the movement of electrons in metal. Reducing the thickness of metal sheets to the order of nanometers can enable exquisite control over how the metal's electrons move. By doing so, one can impart properties that aren't seen in bulk metals, such as ultrafast conduction of electricity. Now, researchers from Osaka University and collaborating partners have synthesized a novel class of nanostructured superlattices. This study enables an unusually high degree of control over the movement of electrons within metal semiconductors, which promises to enhance the functionality of everyday technologies.

Precisely tuning the architecture of metal nanosheets, and thus facilitating advanced microelectronic functionalities, remains an ongoing line of work worldwide. In fact, several Nobel prizes have been awarded on this topic. Researchers conventionally synthesize nanostructured superlattices—regularly alternating layers of metals, sandwiched together—from materials of the same dimension; for example, sandwiched 2D sheets. A key aspect of the present researchers' work is its facile fabrication of hetero-dimensional superlattices; for example, 1D nanoparticle chains sandwiched within 2D nanosheets
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Novel carrier doping in p-type semiconductors enhances photovoltaic device performance by increasing hole concentration
https://phys.org/news/2022-09-carrier-d ... ltaic.html
by Tokyo Institute of Technology
Perovskite solar cells have been the subject of much research as the next generation of photovoltaic devices. However, many challenges remain to be overcome for the practical application. One of them concerns the hole transport layer (p-type semiconductor) in photovoltaic cells that carries holes generated by light to the electrode.

In conventional p-type organic transport semiconductors, hole dopants are chemically reactive and degrade the photovoltaic device. Inorganic p-type semiconductors, which are chemically stable, are promising alternatives, but fabrication of conventional inorganic p-type semiconductors requires high temperature treatment. In this regard, the p-type inorganic semiconductors that can be fabricated at low temperatures and have excellent hole transport ability have been desired.

Inorganic p-type copper iodide (CuI) semiconductor is a leading candidate for such hole transport materials in photovoltaic device applications. In this material, native defects give rise to charge imbalance and free charge carriers. However, the overall number of defects is generally too low for satisfactory device performance.
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A navigation system with 10 centimeter accuracy
https://techxplore.com/news/2022-11-cen ... uracy.html
by Delft University of Technology
Researchers of Delft University of Technology, Vrije Universiteit Amsterdam and VSL have developed an alternative positioning system that is more robust and accurate than GPS, especially in urban settings. The working prototype that demonstrated this new mobile network infrastructure achieved an accuracy of 10 centimeters.

This new technology is important for the implementation of a range of location-based applications, including automated vehicles, quantum communication and next-generation mobile communication systems. The results were published today (Nov. 16) in Nature.

Much of our vital infrastructure relies on global navigation satellite systems such as the U.S. GPS and EU Galileo. Yet these systems that rely on satellites have their limitations and vulnerabilities. Their radio signals are weak when received on Earth, and accurate positioning is no longer possible if the radio signals are reflected or blocked by buildings.

"This can make GPS unreliable in urban settings, for instance," says Christiaan Tiberius of Delft University of Technology and coordinator of the project, "which is a problem if we ever want to use automated vehicles. Also, citizens and our authorities actually depend on GPS for many location-based applications and navigation devices. Furthermore, so far we had no back-up system."

The aim of the project entitled SuperGPS was to develop an alternative positioning system that makes use of the mobile telecommunication network instead of satellites and that could be more robust and accurate than GPS.

"We realized that with a few cutting-edge innovations, the telecommunication network could be transformed into a very accurate alternative positioning system that is independent of GPS," says Jeroen Koelemeij of Vrije Universiteit Amsterdam. "We have succeeded and have successfully developed a system that can provide connectivity just like existing mobile and Wi-Fi networks do, as well as accurate positioning and time distribution like GPS."
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