Subscribe free to our newsletters via your
. Space Industry and Business News .




CHIP TECH
For electronics beyond silicon, a new contender emerges
by Staff Writers
Boston MA (SPX) Sep 17, 2014


"This is a new type of correlated transistor where the transistor action is gated by an ionic field," says principal investigator Shriram Ramanathan. Image courtesy of Jian Shi.

Silicon has few serious competitors as the material of choice in the electronics industry. Yet transistors, the switchable valves that control the flow of electrons in a circuit, cannot simply keep shrinking to meet the needs of powerful, compact devices; physical limitations like energy consumption and heat dissipation are too significant.

Now, using a quantum material called a correlated oxide, Harvard researchers have achieved a reversible change in electrical resistance of eight orders of magnitude, a result the researchers are calling "colossal."

In short, they have engineered this material to perform comparably with the best silicon switches.

The finding arose in what may seem an unlikely spot: a laboratory usually devoted to studying fuel cells-the kind that run on methane or hydrogen-led by Shriram Ramanathan, Associate Professor of Materials Science at the Harvard School of Engineering and Applied Sciences (SEAS). The researchers' familiarity with thin films and ionic transport enabled them to exploit chemistry, rather than temperature, to achieve the dramatic result.

Because the correlated oxides can function equally well at room temperature or a few hundred degrees above it, it would be easy to integrate them into existing electronic devices and fabrication methods. The discovery, published in Nature Communications, therefore firmly establishes correlated oxides as promising semiconductors for future three-dimensional integrated circuits as well as for adaptive, tunable photonic devices.

Challenging silicon
Although electronics manufacturers continue to pack greater speed and functionality into smaller packages, the performance of silicon-based components will soon hit a wall.

"Traditional silicon transistors have fundamental scaling limitations," says Ramanathan. "If you shrink them beyond a certain minimum feature size, they don't quite behave as they should."

Yet silicon transistors are hard to beat, with an on/off ratio of at least 104 required for practical use.

"It's a pretty high bar to cross," Ramanathan explains, adding that until now, experiments using correlated oxides have produced changes of only about a factor of 10, or 100 at most, near room temperature. But Ramanathan and his team have crafted a new transistor, made primarily of an oxide called samarium nickelate, that in practical operation achieves an on/off ratio of greater than 105-that is, comparable to state-of-the-art silicon transistors.

In future work the researchers will investigate the device's switching dynamics and power dissipation; meanwhile, this advance represents an important proof of concept.

"Our orbital transistor could really push the frontiers of this field and say, you know what? This is a material that can challenge silicon," Ramanathan says.

Solid-state chemical doping
Materials scientists have been studying the family of correlated oxides for years, but the field is still in its infancy, with most research aimed at establishing the materials' basic physical properties.

"We have just discovered how to dope these materials, which is a foundational step in the use of any semiconductor," says Ramanathan.

Doping is the process of introducing different atoms into the crystal structure of a material, and it affects how easily electrons can move through it-that is, to what extent it resists or conducts electricity. Doping typically effects this change by increasing the number of available electrons, but this study was different. The Harvard team manipulated the band gap, the energy barrier to electron flow.

"By a certain choice of dopants-in this case, hydrogen or lithium-we can widen or narrow the band gap in this material, deterministically moving electrons in and out of their orbitals," Ramanathan says. That's a fundamentally different approach than is used in other semiconductors. The traditional method changes the energy level to meet the target; the new method moves the target itself.

In this orbital transistor, protons and electrons move in or out of the samarium nickelate when an electric field is applied, regardless of temperature, so the device can be operated in the same conditions as conventional electronics. It is solid-state, meaning it involves no liquids, gases, or moving mechanical parts. And, in the absence of power, the material remembers its present state-an important feature for energy efficiency.

"That's the beauty of this work," says Ramanathan. "It's an exotic effect, but in principle it's highly compatible with traditional electronic devices."

Quantum materials
Unlike silicon, samarium nickelate and other correlated oxides are quantum materials, meaning that quantum-mechanical interactions have a dominant influence over the material properties-and not just at small scales.

"If you have two electrons in adjacent orbitals, and the orbitals are not completely filled, in a traditional material the electrons can move from one orbital to another. But in the correlated oxides, the electrons repulse each other so much that they cannot move," Ramanathan explains.

"The occupancy of the orbitals and the ability of electrons to move in the crystal are very closely tied together-or 'correlated.' Fundamentally, that's what dictates whether the material behaves as an insulator or a metal."

Ramanathan and others at SEAS have successfully manipulated the metal-insulator transition in vanadium oxide, too. In 2012, they demonstrated a tunable device that can absorb 99.75% of infrared light, appearing black to infrared cameras.

Similarly, samarium nickelate is likely to catch the attention of applied physicists developing photonic and optoelectronic devices.

"Opening and closing the band gap means you can now manipulate the ways in which electromagnetic radiation interacts with your material," says Jian Shi, lead author of the paper in Nature Communications. He completed the research as a postdoctoral fellow in Ramanathan's lab at Harvard SEAS and joined the faculty of Rensselaer Polytechnic Institute this fall.

"Just by applying an electric field, you're dynamically controlling how light interacts with this material."

Further ahead, researchers at the Center for Integrated Quantum Materials, established at Harvard in 2013 through a grant from the National Science Foundation, aim to develop an entirely new class of quantum electronic devices and systems that will transform signal processing and computation.

Ramanathan compares the current state of quantum materials research to the 1950s, when transistors were newly invented and physicists were still making sense of them.

"We are basically in that era for these new quantum materials," he says. "This is an exciting time to think about establishing the basic, fundamental properties. In the coming decade or so, this could really mature into a very exciting device platform."

.


Related Links
Harvard School of Engineering and Applied Sciences (SEAS)
Computer Chip Architecture, Technology and Manufacture
Nano Technology News From SpaceMart.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





CHIP TECH
The future face of molecular electronics
Washington DC (SPX) Sep 17, 2014
The emerging field of molecular electronics could take our definition of portable to the next level, enabling the construction of tiny circuits from molecular components. In these highly efficient devices, individual molecules would take on the roles currently played by comparatively-bulky wires, resistors and transistors. A team of researchers from five Japanese and Taiwanese universities ... read more


CHIP TECH
Scientists come closer to the industrial synthesis of a material harder than diamond

Larry Ellison releases helm of mighty Oracle ship

Mussel-inspired MIT glue may have naval, medical applications

'Priceless' 600-tonne jade deposit found in China

CHIP TECH
Space control Airmen ensure constant communication

Russian Aerospace Defense Forces Again Dismiss Satellite Explosion Rumors

Harris Corporation supplying radios to Air Force Special Operations Command

Harris Corporation supply Falcon III RF-340M radios to U.S. military

CHIP TECH
SpaceX is not only taking a 3D printer to space, but mice too

United Launch Alliance Launches Its 60th Mission from Cape Canaveral

Lockheed Martin-built CLIO Satellite Launched From Cape Canaveral

SpaceX cargo capsule nears International Space Station

CHIP TECH
Russia Unable To Reject Foreign Parts in GLONASS Satellites

Talks Over GLONASS Station Locations in US on Hold

Sam Houston State study examines use of GIS in policing

Western Sanctions Fail to Impede GLONASS Satellite Production

CHIP TECH
USMC system for aircraft battle management to be maintained by Lockheed

Japan wants its own early-warning planes: report

Upgrade for F-35's Autonomic Logistics Information System

Upgraded Brazilian Army helo passes evaluation

CHIP TECH
For electronics beyond silicon, a new contender emerges

The future face of molecular electronics

Method detects prize particle for future quantum computing

Program Grows Lasers Directly on Silicon-Based Microchips

CHIP TECH
Dry Conditions and Lightning Strikes Make for a Long California Fire Season

NASA Airborne Campaigns Focus on Climate Impacts in the Arctic

Severe flooding in Northern Pakistan photographed by NASA

EIAST announces Remote Sensing Applications Competition 2014

CHIP TECH
NJIT researchers working to safeguard the shoreline

Mexican authorities say mine still leaking acid

Auf Wiedersehen to plastic at Berlin's no-packaging store

New toxic spill traced to Mexico mine




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.