Transistors

While silk protein has been used in designer electronics, its use is currently limited in part because silk fibers are a messy tangle of spaghetti-like strands. To address this, researchers from Pacific Northwest National Laboratory, University of Washington, Lawrence Berkeley National Laboratory, North Carolina State University and Xiamen University have developed a uniform two-dimensional (2D) layer of silk protein fragments, or "fibroins," on graphene. 

Scheme of silk fibroin assembly on highly oriented pyrolytic graphite (HOPG) characterized by in situ AFM. Image from Science Advances

The scientists explained that their work provides a reproducible method for silk protein self-assembly that is essential for designing and fabricating silk-based electronics. They said that the system is nontoxic and water-based, which is vital for biocompatibility.

Archer Materials has started experiments to detect and monitor chronic kidney disease on its Biochip graphene field effect transistor (“gFET”) sensors.

Archer, through one of its foundry partners, has reportedly verified a process that directly grows graphene surfaces to produce enhanced devices, rather than transferring the graphene to a device from a wafer, as previously done. The team has tested the devices by storing them in normal air conditions over a two-month period, finding no significant degradation in performance. 

Hot-carrier transistors are a class of devices that leverage the excess kinetic energy of carriers. Unlike regular transistors, which rely on steady-state carrier transport, hot-carrier transistors modulate carriers to high-energy states, resulting in enhanced device speed and functionality. These characteristics are essential for applications that demand rapid switching and high-frequency operations, such as advanced telecommunications and cutting-edge computing technologies. However, their performance has been limited by how hot carriers have traditionally been generated.

A team of researchers, led by Prof. Liu Chi, Prof. Sun Dongming, and Prof. CHeng Huiming from the Institute of Metal Research (IMR) of the Chinese Academy of Sciences, has proposed a novel hot carrier generation mechanism called stimulated emission of heated carriers (SEHC). The team has also developed an innovative hot-emitter transistor (HOET), achieving an ultralow sub-threshold swing of less than 1 mV/dec and a peak-to-valley current ratio exceeding 100. The study provides a prototype of a low power, multifunctional device for the post-Moore era.

Archer Materials, a semiconductor company advancing the quantum technology and medical diagnostics industries, has fabricated one of its Biochip graphene field effect transistor (gFET) designs through a six-inch whole wafer run by its foundry partner in Spain, Graphenea.

Archer had sent the Biochip gFET design to Graphenea for fabrication through a whole wafer run in Dec 20231. The gFETs are designed with structures suitable for liquid multiplexing, with advances in chip design features, including in gating design and materials, to address technological challenges in maintaining graphene device stability from chip-to-chip.

Researchers from the University of Göttingen, Japan's National Institute for Materials Science and Massachusetts Institute of Technology (MIT) have demonstrated experimentally that electrons in naturally occurring double-layer graphene move like particles without any mass, in the same way that light travels. Furthermore, they have shown that the current can be "switched" on and off, which has potential for developing tiny, energy-efficient transistors. 

Among its many unusual properties, graphene is known for its extraordinarily high electrical conductivity due to the high and constant velocity of electrons travelling through this material. This unique feature has made scientists try to use graphene for faster and more energy-efficient transistors. The challenge has been that to make a transistor, the material needs to be controlled to have a highly insulating state in addition to its highly conductive state. In graphene, however, such a "switch" in the speed of the carrier cannot be easily achieved. In fact, graphene usually has no insulating state, which has limited graphene's potential a transistor.

Archer Materials has designed a miniaturized version of its Biochip graphene field effect transistor ("gFET") chip for fabrication at a commercial foundry.

The Archer Biochip contains a sensing region of which the gFET is the core component. Each gFET chip contains multiple gFETs, each of which is a transistor, which acts as a sensor. Archer has miniaturized the total chip size by redesigning the layout of the circuits creating these gFET transistors. The new miniaturized design has been sent to a foundry partner for a whole-wafer fabrication of reduced size gFET chips, which Archer intends to integrate with other parts of the Biochip technology.

Traditional microelectronic architectures are currently used to power everything from advanced computers to everyday devices. However, scientists are always on the lookout for better technologies. Recently, Los Alamos National Laboratory scientists and their collaborators from Menlo Systems and Sandia National Laboratories, have designed and fabricated asymmetric, nano-sized gold structures on an atomically thin layer of graphene. The gold structures are dubbed “nanoantennas” based on the way they capture and focus light waves, forming optical “hot spots” that excite the electrons within the graphene. Only the graphene electrons very near the hot spots are excited, with the rest of the graphene remaining much less excited.

Illustration of an optoelectronic metasurface consisting of symmetry-broken gold nanoantennas on graphene. Image from Nature

The team adopted a teardrop shape of gold nanoantennas, where the breaking of inversion symmetry defines a directionality along the structure. The hot spots are located only at the sharp tips of the nanoantennas, leading to a pathway on which the excited hot electrons flow with net directionality — a charge current, controllable and tunable at the nanometer scale by exciting different combinations of hot spots. 

Researchers at Northwestern University, MIT, Harvard University, CIFAR Azrieli Global Scholars Program and Japan's National Institute for Materials Science have developed a graphene-based synaptic transistor capable of higher-level thinking.

The device simultaneously processes and stores information just like the human brain. In new experiments, the researchers demonstrated that the transistor goes beyond simple machine-learning tasks to categorize data and is capable of performing associative learning.

An international team of researchers, including scientists from University of California San Diego, Chinese Academy of Sciences, University of Texas Medical Branch and University of Illinois Urbana-Champaign, has developed a handheld, non-invasive graphene-based device that can detect biomarkers for Alzheimer’s and Parkinson’s Diseases. The biosensor can also transmit the results wirelessly to a laptop or smartphone.

The biosensor consists of a chip with a highly sensitive transistor, made of a graphene layer that is a single atom thick and three electrodes–source and drain electrodes, connected to the positive and negative poles of a battery, to flow electric current, and a gate electrode to control the amount of current flow. Image credit: UCSD

The team tested the device on in vitro samples from patients. The tests reportedly showed the device is as accurate as other state-of-the-art devices. Ultimately, researchers plan to test saliva and urine samples with the biosensor. The device could be modified to detect biomarkers for other conditions as well.

Archer Materials, a semiconductor company advancing the quantum computing and medical diagnostics industries, has demonstrated multiplexing readout for its advanced Biochip graphene field effect transistor (“gFET”) device.

Archer confirmed single-device multiplexing using four advanced gFETs as sensors, which were integrated into the Archer advanced Biochip platform. This is significant as Archer intends to apply its multiplexing capability in the Biochip to test for multiple diseases on a single chip at once.