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Material with increased band gap design could make electronics faster and more efficient

Researchers at the University of Minnesota have achieved a new material that will be pivotal in making the next generation of high-power electronics faster, transparent and more efficient. This artificially designed material allows electrons to move faster while remaining transparent to both visible and ultraviolet light, breaking the previous record. The research, published in Science Advances, marks a significant leap forward in semiconductor design, which is crucial to a trillion-dollar global industry expected to continue growing as digital technologies expand. Semiconductors power nearly all electronics, from smartphones to medical devices. A key to advancing these technologies lies in improving what scientists refer to as "ultra-wide band gap" materials. These materials can conduct electricity efficiently even under extreme conditions. Ultra-wide band gap semiconductors enable high-performance at elevated temperatures, making them essential for more durable and robust electronics.

Researchers have demonstrated that by using a semiconductor with flexible bonds, the material can be moulded into various structures using n

Researchers have demonstrated that by using a semiconductor with flexible bonds, the material can be moulded into various structures using nano containers, without altering its composition, the discovery could lead to the design of a variety of customised electronic devices using only a single element. Semiconductors are vital to our daily lives, as they are found in nearly every electronic device. One of the key characteristics of semiconductors is their band gap, which determines how they conduct electric current. The band gap is typically engineered for specific applications by breaking chemical bonds or introducing additional elements into the material. However, these processes can be complex and energy-intensive.

Researchers create first functional semiconductor made from graphene

Researchers at the Georgia Institute of Technology have created the world's first functional semiconductor made from graphene, a single sheet of carbon atoms held together by the strongest bonds known. Semiconductors, which are materials that conduct electricity under specific conditions, are foundational components of electronic devices. The team's breakthrough throws open the door to a new way of doing electronics. Their discovery comes at a time when silicon, the material from which nearly all modern electronics are made, is reaching its limit in the face of increasingly faster computing and smaller electronic devices. Walter de Heer, Regents' Professor of physics at Georgia Tech, led a team of researchers based in Atlanta, Georgia, and Tianjin, China, to produce a graphene semiconductor that is compatible with conventional microelectronics processing methods—a necessity for any viable alternative to silicon.

To accelerate or decelerate in the light-emitting process of zinc-oxide crystals

Highly efficient electronic and optical devices are essential for reducing energy consumption and for the realization of an eco-friendly society.

ZnO is an attractive material among direct-bandgap semiconductors. They possess light-emitting properties as well as toughness to sustain large electric field that enables them to power electronic devices because of their large bandgap energy and large exciton binding energy. This also makes them suitable in radiation-resistant thin-film-transistors and heterostructure field-effect-transistors.

In high-quality ZnO crystals, nonradiative recombination centers (NRCs) are important for the near-band-edge (NBE) emission. These centers act as undesired energy dissipation channels and reduce the IQE of the NBE emission.

To understand whether the light-emitting process or the non-light-emitting process was more important in determining the behavior of IQE, Kojima and his colleagues measured the IQE values of ZnO crystal grown by the hydrothermal method. To do so, they employed a technique created by Kojima and fellow researchers known as omnidirectional photoluminescence (ODP) spectroscopy—a nondestructive method for probing semiconducting crystals with light to detect defects and impurities.

Turning diamond into metal

Normally an insulator, diamond becomes a metallic conductor when subjected to large strain in a new theoretical model

Long known as the hardest of all natural materials, diamonds are also exceptional thermal conductors and electrical insulators. Now, researchers have discovered a way to tweak tiny needles of diamond in a controlled way to transform their electronic properties, dialing them from insulating, through semiconducting, all the way to highly conductive, or metallic. This can be induced dynamically and reversed at will, with no degradation of the diamond material.

The research, though still at an early proof-of-concept stage, may open up a wide array of potential applications, including new kinds of broadband solar cells, highly efficient LEDs and power electronics, and new optical devices or quantum sensors, the researchers say.

Their findings, which are based on simulations, calculations, and previous experimental results, are reported this week in the Proceedings of the National Academy of Sciences. The paper is by MIT Professor Ju Li and graduate student Zhe Shi; Principal Research Scientist Ming Dao; Professor Subra Suresh, who is president of Nanyang Technological University in Singapore as well as former dean of engineering and Vannevar Bush Professor Emeritus at MIT; and Evgenii Tsymbalov and Alexander Shapeev at the Skolkovo Institute of Science and Technology in Moscow.

The team used a combination of quantum mechanical calculations, analyses of mechanical deformation, and machine learning to demonstrate that the phenomenon, long theorized as a possibility, really can occur in nanosized diamond.

Breaking the absorption limit of silicon toward the short-wavelength infrared wavelength range via strain engineering

Silicon is widely used in the microelectronics industry although its photonics applications are restricted to the visible and partial near-infrared spectral range due to its fundamental optical bandgap. Researchers have therefore used recent advances in strain engineering to tailor material properties, including the optical bandgap. In a recent study now published on Science Advances, Ajit K. Katiyar and a group of scientists in electronic engineering and materials science in the Republic of Korea, reported strain-induced shrinkage in the silicon (Si) bandgap. The process facilitated photosensing beyond the fundamental limit within silicon nanomembrane photodetectors (abbreviated Si-NM PD). The team mechanically stretched the Si-NM PD pixels using a maximum strain of 3.5% to enhance photoresponsivity and extended the silicon absorption limit up to 1550 nm with applications suited for lidar sensors and obstacle detection during self-driving. They then developed a deformable three-dimensional (3-D) optoelectronics framework with concave and convex hemispherical architectures for electronic prototypes displaying wide-angle light detection, bioinspired by the biological eyes of insects.

Paper-thin gallium oxide transistor handles more than 8,000 volts

People love their electric cars. But not so much the bulky batteries and related power systems that take up precious cargo space.

Help could be on the way from a gallium oxide-based transistor under development at the University at Buffalo.

In a study published in the June edition of IEEE Electron Device Letters, electrical engineers describe how the tiny electronic switch can handle more than 8,000 volts, an impressive feat considering it's about as thin as a sheet of paper.

The transistor could lead to smaller and more efficient electronic systems that control and convert electric power—a field of study known as power electronics—in electric cars, locomotives and airplanes. In turn, this could help improve how far these vehicles can travel.

More Efficient Underwater Solar Cells With Optimal Materials

There may be many overlooked organic and inorganic materials that could be used to harness sunlight underwater and efficiently power autonomous submersible vehicles, report researchers at New York University. Their research, publishing today (March 18, 2020) in the journal Joule, develops guidelines for optimal band gap values at a range of watery depths, demonstrating that various wide-band gap semiconductors, rather than the narrow-band semiconductors used in traditional silicon solar cells, are best equipped for underwater use.

“So far, the general trend has been to use traditional silicon cells, which we show are far from ideal once you go to a significant depth since silicon absorbs a large amount of red and infrared light, which is also absorbed by water — especially at large depths,” says Jason A. Röhr, a postdoctoral research associate in Prof. André D. Taylor’s Transformative Materials and Devices laboratory at the Tandon School of Engineering at New York University and an author on the study. “With our guidelines, more optimal materials can be developed.”

Turning diamond into metal

Normally an insulator, diamond becomes a metallic conductor when subjected to large strain in a new theoretical model

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