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Technology Org » Nanotechnology news - 23. 11. 2013

What can happen when graphene meets a semiconductor

 

UWM doctoral student Shivani Rajput, first author on the paper, shows a reconstructed image of graphene with the ripples clearly visible. Two postdoctoral researchers also worked on the project: Yaoyi Li (left) and Mingxing Chen. Credit: Troye Fox For all the promise of graphene as a material for next-generation electronics and quantum computing, scientists still don’t know enough about this high-performance conductor to effectively control an electric current. Graphene, a one-atom-thick layer of carbon, conducts electricity so efficiently that the electrons are difficult to control. And control will be necessary before this wonder material can be used to make nanoscale transistors or other devices. A new study by a research group at the University of Wisconsin-Milwaukee (UWM) will help. The group has identified new characteristics of electron transport in a two-dimensional sheet of graphene layered on top of a semiconductor. The researchers demonstrated that when electrons are rerouted at the interface of the graphene and its semiconducting substrate, they encounter what’s known as a Schottky barrier. If it’s deep enough, electrons don’t pass, unless rectified by applying an electric field – a promising mechanism for turning a graphene-based device on and off. The group also found, however, another feature of graphene that affects the

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Researchers integrate single-crystal BFO onto a silicon chip, open door to smart devices

 

This high-resolution TEM micrograph shows BFO grown on a silicon substrate and aligned with an LSMO (lanthanum strontium manganese oxide) electrode. Researchers from North Carolina State University have for the first time integrated a material called bismuth ferrite (BFO) as a single crystal onto a silicon chip, opening the door to a new generation of multifunctional, smart devices. BFO has both ferromagnetic and ferroelectric properties, meaning that it can be magnetized by running an electric current through the material. Potential applications for BFO include new magnetic memory devices, smart sensors and spintronics technologies. Integrating the BFO into the silicon substrate as a single crystal makes the BFO more efficient by limiting the amount of electric charge that “leaks” out of the BFO into the substrate. “This work means we can now look at developing smart devices that can sense, manipulate and respond to data more quickly because it all happens on one chip – the data doesn’t need to be relayed elsewhere,” says Dr. Jay Narayan, John C. Fan Distinguished Chair Professor of Materials Science and Engineering at NC State and senior author of a paper describing the work. Read more at: Phys.org

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Infrared vision lets researchers see through — and into — multiple layers of graphene

 

It’s not X-ray vision, but you could call it infrared vision. A University at Buffalo-led research team has developed a technique for “seeing through” a stack of graphene sheets to identify and describe the electronic properties of each individual sheet — even when the sheets are covering each other up. The direction that a light wave is oscillating changes as the wave is reflected by a sheet of graphene. Researchers exploited this changing quality to identify the electronic properties of multiple sheets of graphene stacked atop one another even when they were covering each other up. Credit: Chul Soo Kim, U.S. Naval Research Laboratory “We have developed an ultrasensitive fingerprinting tool that is capable of identifying and characterizing different graphene multilayers.” John Cerne, professor of physics University at Buffalo The method involves shooting a beam of infrared light at the stack, and measuring how the light wave’s direction of oscillation changes as it bounces off the layers within. To explain further: When a magnetic field is applied and increased, different types of graphene alter the direction of oscillation, or polarization, in different ways. A graphene layer stacked neatly on top of another will have a different effect on polarization than

The post Infrared vision lets researchers see through — and into — multiple layers of graphene has been published on Technology Org.

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