Electronics - Page 31

Researchers from the University of Luxembourg developed a new materiel which resembles graphene but is made from "traditional semiconductor materials". This so-called "artificial graphene" could be useful in many applications, including electronics, optics, solar cells, lasers and LEDs.

The artificial graphene has the same honeycomb structure as graphene, but it uses nanometer-thick semiconductor crystals instead of carbon atoms. The material's properties can be tuned by changing the size, shape and chemical nature of those nano crystals.

Researchers from France, the US and Germany managed to produce graphene ribbons (GNRs) in which electrons move freely. Those ballistic-at-room-temperature ribbons (ballistic means that there is no resistance) can be produced easily and in large volume, and may find many applications in electronics.

The GNRs are 40 nm wide and feature very high structural quality. The main challenge was to ensure that the edges of the ribbons remained highly ordered. To achieve that, the researcher started with silicon carbide as a substrate, which was etched to have nanometer-deep steps. The graphene ribbons where synthesized directly on the sidewalls of these steps.

Researchers from the US Naval Research Laboratory (NRL) developed a new type of tunnel device structure in which both the tunnel barrier and transport channel are made from graphene. The researchers say that this device features the highest spin injection values yet measured for graphene, and this design could pave they way towards highly functional and scalable graphene electronic and spintronic devices.

The tunnel barrier is made from dilutely fluorinated graphene while the charge and transport layer is made from graphene. The researcher demonstrated tunnel injection through the fluorinated graphene, and lateral transport and electrical detection of pure spin current in the graphene channel.

IBM researchers built a graphene (GFET) based radio frequency receiver IC which they say is the world's most advanced IC ever made of graphene - in fact it offers 10,000 times better performance and any previously reported effort.

IBM's circuit consists of three graphene transistors, four inductors, two capacitors, and two resistors. All circuit components are fully integrated into a 0.6 mm² area and fabricated in a 200 mm silicon production line. The researchers say that those the circuits consume less than 20 mW power to operate, while also demonstrating the highest conversion gain of any graphene RF circuits at multiple GHz frequency.

Researchers from Purdue University developed a new graphene-like 2D material from phosphorus. They call the new material phosphorene and they say that this is the first native 2D p-type semiconductor, making it more useful than graphene to make transistors.

Together with MoS₂ (a 2D n-type semiconductor), it is now possible to build switches made from 2D materials. Graphene in its basic form is a superconductor and so is less suited to make transistors.

Researchers from MIT discovered that under a powerful magnetic field and at very low temperatures, graphene can filter electrons according to the direction of their spin. This is something that cannot be done by any conventional electronic system - and may make graphene very useful for quantum computing.

It is known that when a magnetic field is turned on perpendicular to a graphene flake, current flows only along the edge, and in one direction (clockwise or counterclockwise, depending on the magnetic field orientation), while the bulk graphene sheet remains insulating. This is called the Quantum Hall effect.

Researchers from the US, Singapore, Brazil and Ireland have theoretically shown that if you fold a graphene sheet in a fin-like structure and expose it to a magnetic field you open up a bandgap. This will also produce spin-polarized current, which should make it useful in Spintronics applications.

The researchers say that this folding can be easily achieved by depositing graphene on a substrate with periodic trenches.

Researchers from MIT and the University of California at Berkeley developed a new way to evenly functionalize graphene with oxygen at low (50-80 C) temperatures. The method is environmentally friendly (no harsh chemical treatment) and can be applied on a large scale.

The researchers use low-temperature annealing and this cause the oxygen atoms to form clusters. This leaves areas of pure-graphene between the oxygen clusters. This decreases the graphene's electrical resistance by four to five orders of magnitude (the oxygen clusters are insulating) which is good for applications such as sensing, electronics and catalysis.

Researchers from the Max Planck Institute for Polymer Researcher developed a new method to produce very long and well-defined graphene nanoribbons (GNRs). The resulting defect-free ribbons are liquid-phase-processable and could enable effective transistors and other electronic devices.

The new method is a bottom-up one - synthesizing graphene ribbons from molecular building blocks. This method is a modification to the solution-mediated production method developed in 2011 by the same group.

Researchers from the Georgia Institute of Technology are developing graphene-based micro antennas that can be used to connect low-power small devices. Graphene can be used to generate a type of electronic surface wave that would allow antennas just one micron long and 10 to 11 nanometers wide.

The researchers haven't yet produced any prototype, but according to their simulations and modeling such antennas are possible. The next step is to actually fabricate a graphene nano-antenna and operate it using a transceiver also based on graphene.