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Posted: Jun 27, 2016

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(Nanowerk News) In movies and television series, audio tapes or other devices self-destruct after delivering the details of impossible missions. Scientists at the Georgia Institute of Technology have taken it to a new level with an electron-beam writing technique that induces the deposition of carbon on a graphene surface (Nanoscale, "Dynamic modulation of electronic properties of graphene by localized carbon doping using focused electron beam induced deposition").
The deposits control the material’s nanoscale electronic properties and create junctions between electron-rich (where the carbon was deposited) and electron-deficient regions. These junctions could enable nanoscale electronics. Over time, the deposited carbon diffuses on the surface, which could dynamically change how the device functions.
electron-beam (e-beam) technique adds carbon atoms to two-dimensional graphene
A new electron-beam (e-beam) technique adds carbon atoms to two-dimensional graphene, the equivalent of “writing” on the surface and controlling the electronic properties at the nanoscale. These electronic properties change over time, which could allow a device to function one way now and another way later – allowing the original information to “disappear.” The schematic shows the ability to draw an electron-rich carbon region (black rectangle labeled “FEBID Carbon”). Carbon deposition is induced near the e-beam and controlled by an electron dose. The atomic force microscopy image of the junction between the graphene domains shows an electron-rich, carbon-enhanced region (left) and electron-deficient region (right). Such a nanoscale junction between domains with different electronic properties could control how a device functions. (click on image to enlarge)
This electron-beam technique allows for nanoscale engineering of future graphene-based devices for information and energy storage, sensors, as well as nanoelectronics that could be re-configurable with dynamic function.
Scientist have developed a novel “direct-write” additive lithographic technique that can be used to electronically pattern graphene materials at the nanoscale. The technique is called focused electron beam induced deposition (FEBID) and can be used to engineer nanoscale electronic properties of graphene.
This technique can form conduction channels in graphene for a variety of applications, such as transistors and energy storage devices.
The “direct write” technique controllably induces deposition of carbon, which locally changes the electronic properties of graphene. Changing the energy, exposure, and location of the e-beam controls the carbon deposition.
Additionally, the carbon diffuses on the surface over time, dynamically changing the local electronic properties. These experimental findings not only highlight a unique capability for locally controlling graphene’s electronic properties, but also suggest a possibility of using FEBID for local “functional patterning” of other two-dimensional nanomaterials.
Scientists have shown how to prepare nanoscale junctions of materials with different electronic properties using an e-beam technique, providing new possibilities of developing graphene-based devices that can adapt their electronic functionality.
Source: Department of Energy, Office of Science
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