Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Navy Scientists Demonstrate Breakthrough in Tunnel Barrier Technology

Diagram (left) of the graphene-based magnetic tunnel junction, where a single atom thick layer of carbon atoms in a honeycomb lattice separates two magnetic metal films (cobalt and permalloy). The magnetizations of the films can be aligned parallel or antiparallel, resulting in a change in resistance for current flowing through the structure, called the tunnel magnetoresistance (TMR). The plot (right) shows the TMR as an applied magnetic field changes the relative orientation of the magnetizations — the TMR persists well above room temperature.
(U.S. Naval Research Laboratory)
Diagram (left) of the graphene-based magnetic tunnel junction, where a single atom thick layer of carbon atoms in a honeycomb lattice separates two magnetic metal films (cobalt and permalloy). The magnetizations of the films can be aligned parallel or antiparallel, resulting in a change in resistance for current flowing through the structure, called the tunnel magnetoresistance (TMR). The plot (right) shows the TMR as an applied magnetic field changes the relative orientation of the magnetizations — the TMR persists well above room temperature.

(U.S. Naval Research Laboratory)

Abstract:
Scientists at the Naval Research Laboratory have demonstrated, for the first time, the use of graphene as a tunnel barrier — an electrically insulating barrier between two conducting materials through which electrons tunnel quantum mechanically. They report fabrication of magnetic tunnel junctions using graphene, a single atom thick sheet of carbon atoms arranged in a honeycomb lattice, between two ferromagnetic metal layers in a fully scalable photolithographic process. Their results demonstrate that single-layer graphene can function as an effective tunnel barrier for both charge and spin-based devices, and enable realization of more complex graphene-based devices for highly functional nanoscale circuits, such as tunnel transistors, non-volatile magnetic memory and reprogrammable spin logic. These research results are published in the online issue of Nano Letters (14 May 2012; DOI: 10.1021/nl3007616).

Navy Scientists Demonstrate Breakthrough in Tunnel Barrier Technology

Washington, DC | Posted on July 31st, 2012

The research initiates a "paradigm shift in tunnel barrier technology for magnetic tunnel junctions (MTJs) used for advanced sensors, memory and logic," explains NRL's Dr. Berend Jonker. Graphene has been the focus of intense research activity because of its remarkable electronic and mechanical properties. In the past, researchers focused on developing graphene as a conductor, or perhaps a semiconductor, where the current flows in-plane parallel to the carbon honeycomb sheet. In contrast, the NRL researchers show that graphene serves as an excellent tunnel barrier when current is directed perpendicular to the plane, and in fact, also preserves the spin polarization of the tunneling current.

Tunnel barriers are the basis for many electronic (charge-based) and spintronic (spin-based) device structures. Fabrication of ultra-thin and defect-free barriers is an ongoing challenge in materials science. Typical tunnel barriers are based on metal oxides (e.g. aluminum oxide or magnesium oxide), and issues such as non-uniform thicknesses, pinholes, defects and trapped charge compromise their performance and reliability. Such oxide tunnel barriers have several limitations which hinder future performance. For example, they have high resistance-area (RA) products which results in higher power consumption and local heating; they allow interdiffusion at the interfaces, which reduces their performance and can lead to catastrophic failure; and their thickness is generally non-uniform, resulting in "hot spots" in the current transport. In contrast, Dr. Jonker explains, the inherent material properties of graphene make it an ideal tunnel barrier. Graphene is chemically inert and impervious to diffusion even at high temperatures. The atomic thickness of graphene represents the ultimate in tunnel barrier scaling for the lowest possible RA product, lowest power consumption and fastest switching speed.

This discovery by NRL researchers is significant because MTJs are widely utilized as read heads in the hard disk drive found in every computer, and as memory elements in non-volatile magnetic random access memory (MRAM) which is rapidly emerging as a universal memory replacement for the many varieties of conventional semiconductor-based memory. They are also considered to be lead contenders as reprogrammable, non-volatile elements for a universal logic block.

Although there has been significant progress, the emerging generation of MTJ-based MRAM relies upon spin-transfer torque switching, and is severely limited by the unacceptably high current densities required to switch the logic state of the cell. The accompanying issues of power consumption and thermal dissipation prevent scaling to higher densities and operation at typical CMOS voltages. The 2011 International Technology Roadmap for Semiconductors (ITRS) states that "all of the existing forms of nonvolatile memory face limitations based on material properties. Success will hinge on finding and developing alternative materials and/or developing alternative emerging technologies ... development of electrically accessible non-volatile memory with high speed and high density would initiate a revolution in computer architecture ... and provide a significant increase in information throughput beyond the traditional benefits of scaling when fully realized for nanoscale CMOS devices" (ITRS 2011 Executive Summary, p28; and Emerging Research Devices, p. 4).

NRL researchers believe that the graphene-based magnetic tunnel junctions they have demonstrated will eclipse the performance and ease of fabrication of existing oxide technology. These graphene-based MTJs would be a breakthrough for nascent spin-based technologies like MRAM and spin logic, and enable the electrically accessible non-volatile memory required to initiate a revolution in computer architecture. These results also pave the way for utilization of other two-dimensional materials such as hexagonal boron nitride for similar applications.

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

####

About U.S. 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:
The NRL Public Affairs Office
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 Links

NRL homepage

Related News Press

Graphene

Haydale and Goodfellow Announce Major Distribution Agreement for Functionalised Graphene Materials July 21st, 2014

CIQUS researchers develop an extremely simple procedure to obtain nanosized graphenes July 15th, 2014

Openings/New facilities/Groundbreaking/Expansion

Oxford Instruments Asylum Research Opens an Atomic Force Microscopy Demonstration Lab in Mumbai, India July 21st, 2014

Sono-Tek Corporation Announces New Clean Room Rated Laboratory Facility in China July 18th, 2014

Laboratories

Sono-Tek Corporation Announces New Clean Room Rated Laboratory Facility in China July 18th, 2014

Fundamental Chemistry Findings Could Help Extend Moore’s Law: A Berkeley Lab-Intel collaboration outlines the chemistry of photoresist, enabling smaller features for future generations of microprocessors July 15th, 2014

Labs characterize carbon for batteries: Rice, Lawrence Livermore scientists calculate materials’ potential for use as electrodes July 14th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Oregon chemists eye improved thin films with metal substitution: Solution-based inorganic process could drive more efficient electronics and solar devices July 21st, 2014

More than glitter: Scientists explain how gold nanoparticles easily penetrate cells, making them useful for delivering drugs July 21st, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Tiny laser sensor heightens bomb detection sensitivity July 19th, 2014

Chip Technology

Dongbu HiTek Unveils Low-Voltage BCDMOS Process for Efficient Power Management in Smart Phones and Tablet Computers July 21st, 2014

Oregon chemists eye improved thin films with metal substitution: Solution-based inorganic process could drive more efficient electronics and solar devices July 21st, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Martini Tech Inc. becomes the exclusive distributor for Yoshioka Seiko Co. porous chucks for Europe and North America July 20th, 2014

Memory Technology

Rice's silicon oxide memories catch manufacturers' eye: Use of porous silicon oxide reduces forming voltage, improves manufacturability July 10th, 2014

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

Leti to Present Technological Platforms Targeting Industry’s Needs for the Future at Semicon West Workshop: Presentation at STS Session to Focus on Leti Advanced Lithography Programs for 1x Nodes and on Silicon Photonics at TechXPot June 25th, 2014

6TH CEA-LETI WORKSHOP ON INNOVATIVE MEMORY TECHNOLOGIES includes invited talks by Infineon, IBM, Schlumberger, Thales, Cisco and STMicroelectronics: June 24 Event to Explore NVM Application Horizons from Automotive to Oil & Gas: Responses from Innovative Technologies & Design June 12th, 2014

Discoveries

Oregon chemists eye improved thin films with metal substitution: Solution-based inorganic process could drive more efficient electronics and solar devices July 21st, 2014

Steam from the sun: New spongelike structure converts solar energy into steam July 21st, 2014

More than glitter: Scientists explain how gold nanoparticles easily penetrate cells, making them useful for delivering drugs July 21st, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Announcements

Oxford Instruments Asylum Research Opens an Atomic Force Microscopy Demonstration Lab in Mumbai, India July 21st, 2014

Steam from the sun: New spongelike structure converts solar energy into steam July 21st, 2014

More than glitter: Scientists explain how gold nanoparticles easily penetrate cells, making them useful for delivering drugs July 21st, 2014

Iran to Host 1st Asian Congress on Nanostructures on Kish Island July 21st, 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