Tuesday, October 11, 2011

ITE 221 - Fall 2011 - Chapter 5

Article Review "Nonvolatile memory based on ferroelectric-graphene field-effect transistors is now a step closer to reality" by Lee Swee Heng, 24 Feb 11 at www.physorg.com/pdf217772766.pd

     Graphene is a single atom-thick layer of carbon atoms bonded in a hexagonal honeycomb-like arrangement that has unique electrical, optical, mechanical and thermal properties. As a result, its technological applications are researched across a wide range of applications. In fact, the Nobel Prize for Physics  for 2010 was awarded to Andre Geim and Konstantin Novoselov   "for groundbreaking experiments regarding the two-dimensional material graphene." One example is its potential use as a viable, high-performance replacement for silicon to provide nonvolatile memory for field effect transistors (FETs). 
        According to this article, scientists from two teams, the A*STAR Institute of Materials Research and Engineering and the National University of Singapore, led by Kui Yao and Barbaros Özylmaz,have collaborated to fabricate a device that includes an additional silicon dioxide (SiO2) dielectric gate below the graphene layer to simplify bit writing by providing an additional background source of charge carriers. This solved a previous problem by allowing the ferroelectric polarization to be switched between two stable states corresponding to two opposite polarization orientations. The team met with success  including the capability for symmetrical bit writing with a resistance ratio  of over 500% and reproducible nonvolatile switching over 100,000 cycles. These reversible switches could potentially be applied to nonvolatile memory. 

The full study can be found at http://prl.aps.org/abstract/PRL/v105/i16/e166602.
 

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