Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > NRL Researchers Discover New Route to Spin-Polarized Contacts on Silicon

NRL scientists successfully used graphene, a single layer of carbon atoms in a honeycomb lattice (gray), as a tunnel barrier to electrically inject spin polarized electrons from a ferromagnetic NiFe contact (red) into a silicon substrate (purple). The net spin accumulation in the silicon produces a voltage, which can be directly measured. Spin injection, manipulation and detection are the fundamental elements allowing information processing with the electron spin rather than its charge.
(Image: U.S. Naval Research Laboratory)
NRL scientists successfully used graphene, a single layer of carbon atoms in a honeycomb lattice (gray), as a tunnel barrier to electrically inject spin polarized electrons from a ferromagnetic NiFe contact (red) into a silicon substrate (purple). The net spin accumulation in the silicon produces a voltage, which can be directly measured. Spin injection, manipulation and detection are the fundamental elements allowing information processing with the electron spin rather than its charge.

(Image: U.S. Naval Research Laboratory)

Abstract:
Scientists at the Naval Research Laboratory have demonstrated that graphene, a single layer of carbon atoms in a honeycomb lattice, can serve as a low resistance spin-polarized tunnel barrier contact which successfully enables spin injection/detection in silicon from a ferromagnetic metal. The graphene provides a highly uniform, chemically inert and thermally robust tunnel barrier free of defects and trap states which plague oxide barriers. This discovery clears an important hurdle to the development of future semiconductor spintronic devices, that is, devices which rely on manipulating the electron's spin rather than its charge for low-power, high-speed information processing beyond the traditional size scaling of Moore's Law. The research results are reported in a paper published in Nature Nanotechnology on September 30, 2012 (DOI 10.1038/nnano.2012.161).

NRL Researchers Discover New Route to Spin-Polarized Contacts on Silicon

Washington, DC | Posted on October 23rd, 2012

Ferromagnetic metals, such as iron or permalloy, have intrinsically spin-polarized electron populations (more "spin-up" electrons than "spin-down", see figure), and are thus ideal contacts for injection and detection of spin in a semiconductor. An intervening tunnel barrier is required to avoid saturation of both semiconductor spin channels by the much larger metal conductivity - this would otherwise result in no net spin polarization in the semiconductor. However, the oxide barriers typically used (such as Al2O3 or MgO) introduce defects, trapped charge and interdiffusion, and have resistances, which are too high - all of these factors severely impact the performance. To solve this problem, the NRL research team, led by Dr. Berend Jonker, used single layer graphene as the tunnel barrier. This novel approach utilizes a defect resistant, chemically inert and stable material with well-controlled thickness to achieve a low resistance spin contact compatible with both the ferromagnetic metal and semiconductor of choice. These qualities insure minimal diffusion to/ and from the surrounding materials at temperatures required for device manufacturing.

The research team used this approach to demonstrate electrical generation and detection of spin accumulation in silicon above room temperature, and showed that the contact resistance-area products are 100 to 1000 times lower than achieved with oxide tunnel barriers on silicon substrates with identical doping levels.

These results identify a new route to low resistance-area product spin-polarized contacts, a key requirement for semiconductor spintronic devices that rely upon two-terminal magnetoresistance, including spin-based transistors, logic and memory, explains NRL's Dr. Berend Jonker.

In looking to the future, the NRL team suggests that the use of multilayer graphene in such structures may provide much higher values of the tunnel spin polarization due to band structure derived spin filtering effects which have been predicted for selected ferromagnetic metal / multi-layer graphene structures. This increase would improve the performance of semiconductor spintronic devices by providing higher signal to noise ratios and corresponding operating speeds, advancing the techological applications of silicon spintronics.

The NRL research team includes Dr. Olaf van 't Erve, Dr. Adam Friedman, Dr. Enrique Cobas, Dr. Connie Li, and Dr. Berend Jonker from the Materials Science and Technology Division, and Dr. Jeremy Robinson from the Electronics Science and Technology Division.

####

About Naval Research Laboratory
The U.S. Naval Research Laboratory is the Navy's full-spectrum corporate laboratory, conducting a broadly based multidisciplinary program of scientific research and advanced technological development. The Laboratory, with a total complement of nearly 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 85 years and continues to meet the complex technological challenges of today's world. For more information, visit the NRL homepage or join the conversation on Twitter, Facebook, and YouTube.

For more information, please click here

Contacts:
Donna McKinney
(202) 767-2541

Copyright © U.S. Naval Research Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

‘Small’ transformation yields big changes September 16th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

Rice rolls 'neat' nanotube fibers: Rice University researchers' acid-free approach leads to strong conductive carbon threads September 15th, 2014

Simple, Cost-Effective Method Proposed for Synthesizing Zinc Oxide Nanopigments September 15th, 2014

Graphene

New pricing report for bulk graphene materials September 13th, 2014

Molecular self-assembly controls graphene-edge configuration September 10th, 2014

Penn Engineers Advance Understanding of Graphene’s Friction Properties September 10th, 2014

Material development on the nanoscale: Doped graphene nanoribbons with potential September 8th, 2014

Govt.-Legislation/Regulation/Funding/Policy

‘Small’ transformation yields big changes September 16th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

Seeking Nanoscale Defenses for Biological and Chemical Threats: WPI co-organizes a NATO workshop to improve the detection and decontamination of biological and chemical agents September 13th, 2014

Spintronics

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Molecular engineers record an electron's quantum behavior August 14th, 2014

Diamond defect interior design: Planting imperfections called 'NV centers' at specific spots within a diamond lattice could advance quantum computing and atomic-scale measurement August 5th, 2014

University of Illinois study advances limits for ultrafast nano-devices July 10th, 2014

Chip Technology

‘Small’ transformation yields big changes September 16th, 2014

UT Arlington research uses nanotechnology to help cool electrons with no external sources September 11th, 2014

Excitonic Dark States Shed Light on TMDC Atomic Layers: Berkeley Lab Discovery Holds Promise for Nanoelectronic and Photonic Applications September 11th, 2014

Researchers Create World’s Largest DNA Origami September 11th, 2014

Discoveries

‘Small’ transformation yields big changes September 16th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Rice rolls 'neat' nanotube fibers: Rice University researchers' acid-free approach leads to strong conductive carbon threads September 15th, 2014

Simple, Cost-Effective Method Proposed for Synthesizing Zinc Oxide Nanopigments September 15th, 2014

Announcements

‘Small’ transformation yields big changes September 16th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

Rice rolls 'neat' nanotube fibers: Rice University researchers' acid-free approach leads to strong conductive carbon threads September 15th, 2014

Simple, Cost-Effective Method Proposed for Synthesizing Zinc Oxide Nanopigments September 15th, 2014

Military

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

Seeking Nanoscale Defenses for Biological and Chemical Threats: WPI co-organizes a NATO workshop to improve the detection and decontamination of biological and chemical agents September 13th, 2014

UT Arlington research uses nanotechnology to help cool electrons with no external sources September 11th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE