Electronics - Page 11

Researchers at the University of Delaware have invented a technology that is meant to improve the communication between photonics devices. This new innovation could benefit smartphones, laptops, and various other consumer electronics.

silicon-graphene devices capable of transmitting radio-frequency waves at less than a picosecond at a sub-terahertz bandwidth have been successfully created. Silicon has long been a popular material for use in semiconductors found in many electronic devices. Unfortunately, there is a limit to what silicon can do in a semiconductor, due to its carrier mobility. This means that the speed a charge moves through the material, and its indirect bandgap, can dramatically limit the material’s ability to absorb and release light. But scientists believe they’ve found a solution to this problem, in the form of graphene.

Due to graphene's 2D geometry, most of the device applications require graphene to be partially or fully supported by a substrate, which is typically silicon dioxide (SiO₂). An important example of a typical graphene structure on SiO₂ is the graphene field effect transistor GFET, a sheet of graphene connected to metal terminals on the planar substrate. The current common understanding is that graphene interacts with SiO₂ through weak, long-range van der Waals forces, even though experimental evidence suggests a surprisingly strong interaction between graphene and SiO2 that affects all properties of the device.

Now, a multinational research team from the University of Trento, Italian Space Agency and Fondazione Bruno Kessler in Italy, Graphenea in Spain, Institute of Chemical Engineering Sciences and University of Patras in Greece, and Queen Mary University of London in the UK has shown that surface charges on the oxide are a main factor of strong interaction between graphene and SiO₂, paving the way for designing 2D material interaction with a substrate through manipulation of surface charges. Such control of graphene-substrate interactions would facilitate the development of new graphene-based microelectronic devices.

Researchers in India have made graphene field-effect transistors based on discrete inorganic structures that reportedly work for over 10 months. The approach has led them to produce a graphene logic inverter that is stable in ambient conditions.

Conventional electronics are silicon based, due to the ease of doping silicon with either electrons or holes. These two forms of silicon, n- and p-type, are the building blocks of electronic devices. However, it isn’t possible to make silicon electronics on the nanoscale, so many researchers are turning to materials like graphene.

University of Cambridge spin-out company, Paragraf, recently announced that it started producing graphene at up to eight inches (20cm) in diameter, large enough for commercial electronic devices.

Paragraf is producing graphene ‘wafers’ and graphene-based electronic devices, which could be used in transistors, where graphene-based chips could deliver speeds more than ten times faster than silicon chips; and in chemical and electrical sensors, where graphene could increase sensitivity by a factor of more than 30. The company’s first device will reportedly be available in the next few months.

A technology developed by a team led by Dr. Núria Crivillers, researcher at the Nanomol Group at ICMAB, has been selected as a high potential innovation by the European Union (EU).

The EU recently launched the Innovation Radar tool, an initiative to identify high potential innovations and innovators in EU-funded research and to increase their visibility through the Innovation Radar website, making them available to potential users and to the society.

Graphene Flagship researchers at DTU, Denmark, solved the problem of graphene's accumulation of defects and impurities due to environmental exposure by protecting it with insulating layers of hexagonal boron nitride, another two-dimensional material with insulating properties.

Peter Bøggild, researcher at Graphene Flagship partner DTU and coauthor of the paper, explains that although 'graphene is a fantastic material that could play a crucial role in making new nano-sized electronics, it is still extremely difficult to control its electrical properties.' Since 2010, scientists at DTU have tried to tailor the electrical properties of graphene, by making a very fine pattern of holes, so that channels through which an electric power can flow freely are formed. 'Creating nanostructured graphene turned out to be amazingly difficult, since even small errors wash out all the properties we designed it to have,' comments Bøggild.

The labs of Rice University chemist James Tour and Christopher Arnusch, a professor at Ben-Gurion University of the Negev in Israel, introduced a batch of graphene-enhanced composites that can be a step towards more robust packages.

By infusing laser-induced graphene with plastic, rubber, cement, wax or other materials, the lab made composites with a wide range of possible applications. These new composites could be used in wearable electronics, in heat therapy, in water treatment, in anti-icing and deicing work, in creating antimicrobial surfaces and even in making resistive random-access memory devices.

A team of European researchers from the KTH Royal Institute of Technology, Chalmers University of Technology and Uppsala University in Sweden, along with scientists from RWTH Aachen University and AMO GmbH in Germany, has discovered that when graphene is integrated with the metal of a circuit, contact resistance is not impaired by humidity. This finding may help to develop new sensors with a significant cost reduction.

To achieve efficient sensors, graphene needs to make good electrical contacts when integrated with a conventional electronic circuit. Such proper contacts are crucial in any sensor and significantly affect its performance. But a common problem is that graphene is sensitive to humidity, to the water molecules in the surrounding air that are adsorbed onto its surface. The H₂O molecules change the electrical resistance of the graphene material, which introduces a false signal into the sensor.

Researchers have fully characterized graphene nanoribbons (GNRs) with a clear route towards upscaling the production. Two-dimensional sheets of graphene in the form of ribbons a few tens of nanometers across have unique properties that are highly interesting for use in future electronics.

The nanoribbons were grown on a template made of silicon carbide under well controlled conditions and thoroughly characterized by a research team from MAX IV Laboratory, Techniche Universität Chemnitz, Leibniz Universität Hannover, and Linköping University. The template has ridges running in two different crystallographic directions to let both the armchair and zig-zag varieties of graphene nanoribbons form. The result is a predictable growth of high-quality graphene nanoribbons which have a homogeneity over a millimeter scale and a well-controlled edge structure.

This is a guest post by Guillaume Chansin

Graphene is probably the most hyped material of the past decade, but so far commercial applications have been limited. Graphene is mostly used as an additive inside composites and plastics to enhance their thermal or structural properties. In the most recent high profile case, Huawei announced the integration of a passive graphene cooling film to improve heat management inside one of their smartphones. While this is a useful use of graphene, it is a far cry from the disruptive electronics that were promised when the material was first isolated.

It is worth considering that both investments and patent filings in graphene peaked in 2015. Nearly four years later, we can expect to see some of these to start paying off with some product launches.