Electronics - Page 39

Researchers from Samsung and the University of California developed a new Flash memory device that integrates both Silicon and Graphene. The idea is to use graphene as the storage layer - which extends the capabilities of the conventional silicon based technology. The new prototypes use less energy and store data more stably over time.

The graphene memory cells also do not electrically interfere with one another, which means that it'll be easier to scale these cells and make them smaller than regular flash cells.

Researchers demonstrated a 3x improvement in electron mobility of epitaxial graphene (and similar improvement in radio-frequency transistor performance) by adding hydrogen to the Graphene. They reported an extrinsic cut-off frequency of 24 GHz in transistor performance, the highest reported so far in a real-world epitaxial graphene device.

The hydrogenation technique involves turning the buffer layer into a second, free-floating one-atom-thick layer of graphene by passivating dangling carbon bonds using hydrogen. This results in two free-floating layers of graphene. An additional process step fully converts the buffer layer to graphene. With this hydrogenation technique, the epitaxial graphene test structures showed a 200-300% increase in carrier mobility, from 700-900 cm2/(V s) to an average of 2050 cm2/(V s) in air and 2375 cm2/(V s) in vacuum.

Graphene can adsorb oxygen onto its surface (which changes graphene's electronic transport properties). This can be useful for Spintronics devices, but the adsorption is difficult to control. Researchers from the Tokyo Institute of Technology developed a way to control the adsorption of oxygen by applying an electric field to a Graphene-based field-effect transistor (FET).

The density of carriers (electrons and holes) in the FET can be tuned by applying an electric field to the gate of the device and, when oxygen molecules then adsorb onto the device, the conductivity of the FET changes.

New research shows that graphene can be chemically doped using nitrogen atoms - which suggests that graphene electronics can use processes used in silicon based technology. The research also confirmed that you can use other elements (such as Boron) to complementary dope graphene.

As is the case in Silicon, the extra nitrogen atoms do not significantly modify the basic structure of graphene sheets.

Researchers from the University of Manchester (in partnership with other scientists at the Universities of Moscow, Nijmegen and Lancaster) published some new information about the interactions between electrons in bilayer graphene.

The researchers utilized superior quality bilayer graphene instruments that were fabricated by suspending graphene sheets in vacuum (this method could remove majority of the unnecessary scattering methods of electrons in graphene, thus improving the electron to electron interaction effect).

Dr. Bhagawan Sahu from the Microelectronics research center in Texas, Dr. Bhagawan Sahu is working on creating digital circuits made from graphene. Check out this interesting interview with Dr. Sahu - where he discusses the fundamental advantages of using graphene in electronics, and the potential for creating the first commercially available graphene digital microprocessors by 2023.

Scientists from The University of Nottingham, UK, developed a new self-assembly based method to create sulphur-terminated graphene nanoribbon within a single-walled carbon nanotube. The team have demonstrated that carbon nanotubes can be used as nanoscale chemical reactors and chemical reactions involving carbon and sulphur atoms held within a nanotube lead to the formation of atomically thin strips of carbon, known as graphene nanoribbon, decorated with sulphur atoms around the edge.

These ribbons have some interesting physical properties and they are suitable for applications in electronic and spintronics devices - more so than 'regular' graphene.

Foa Torres, a scientist from the National University of Córdoba in Argentina, says that Graphene's Achilles heel is the fact that it does not have a band gap. This means that Graphene cannot be 'turned-off', and so you can't use it for active electronic devices such as switches and transistors.

Foa Torres predicts that shining a mid-infrared laser on graphene can produce band gaps in its electronic structure, and this band gap could be tuned by controlling the laser polarization. The next crucial step is experimental verification.

A research team from UCLA announce they have developed a scalable approach to fabricate high-speed graphene transistors. Back in September 2010, this team developed 300Ghz graphene transistors, making them using a nanowire as the self-aligned gate.

The new approach uses a dielectrophoresis assembly approach to precisely place nanowire gate arrays on large-area chemical vapor depositiongrowth graphene (as opposed to mechanically peeled graphene flakes) to enable the rational fabrication of high-speed transistor arrays. This was made on a glass substrate. The new transistors have cut-off frequencies of over 50Ghz (typical graphene transistors made on silicon have cut-off frequencies of less then 10 Ghz).

IBM developed a 10 Ghz integrated circuit (IC) made from Graphene. This research proved that graphene can be fabricated on a wafer - similar to silicon chips and graphene transistors can be bonded with components from other materials.

According to IBM, there are big advantages in using graphene in analog components, and that's where IBM is focusing its work. IBM already developed a 100Ghz graphene transistor and plans to develop a 1Thz one. In a different research, IBM developed a graphene transistor with a record cut-off frequency of 155 Ghz and the shortest gate length ever .