Navigation Links
UCLA Engineering advance with new nanomaterials good news for next-generation electronic devices

In recent years, topological insulators have become one of the hottest topics in physics. These new materials act as both insulators and conductors, with their interior preventing the flow of electrical currents while their edges or surfaces allow the movement of a charge.

Perhaps most importantly, the surfaces of topological insulators enable the transport of spin-polarized electrons while preventing the "scattering" typically associated with power consumption, in which electrons deviate from their trajectory, resulting in dissipation.

Because of such characteristics, these materials hold great potential for use in future transistors, memory devices and magnetic sensors that are highly energy efficient and require less power.

In a study published Feb. 13 in Nature Nanotechnology, researchers from UCLA's Henry Samueli School of Engineering and Applied Science and from the materials division of Australia's University of Queensland show the promise of surface-conduction channels in topological insulator nanoribbons made of bismuth telluride and demonstrate that surface states in these nanoribbons are "tunable" able to be turned on and off depending on the position of the Fermi level.

"Our finding enables a variety of opportunities in building potential new-generation, low-dissipation nanoelectronic and spintronic devices, from magnetic sensing to storage," said Kang L. Wang, the Raytheon Professor of Electrical Engineering at UCLA Engineering, whose team carried out the research.

Bismuth telluride is well known as a thermoelectric material and has also been predicted to be a three-dimensional topological insulator with robust and unique surface states. Recent experiments with bismuth telluride bulk materials have also suggested two-dimensional conduction channels originating from the surface states. But it has been a great challenge to modify surface conduction, because of dominant bulk contribution due to impurities and thermal excitations in such smallband-gap semiconductors.

The development of topological insulator nanoribbons has helped. With their large surface-to-volume ratios, these nanoribbons significantly enhance surface conditions and enable surface manipulation by external means.

Wang and his team used thin bismuth telluride nanoribbons as conducting channels in field-effect transistor structures. These rely on an electric field to control the Fermi level and hence the conductivity of a channel. The researchers were able to demonstrate for the first time the possibility of controlling surface states in topological insulator nanostructures.

"We have demonstrated a clear surface conduction by partially removing the bulk conduction using an external electric field," said Faxian Xiu, a UCLA staff research associate and lead author of the study. "By properly tuning the gate voltage, very high surface conduction was achieved, up to 51 percent, which represents the highest values in topological insulators."

"This research is very exciting because of the possibility to build nanodevices with a novel operating principle," said Wang, who is also associate director of the California NanoSystems Institute (CNSI) at UCLA. "Very similar to the development of graphene, the topological insulators could be made into high-speed transistors and ultrahigh-sensitivity sensors."

The new findings shed light on the controllability of the surface spin states in topological insulator nanoribbons and demonstrate significant progress toward high surface electric conditions for practical device applications. The next step for Wang's team is to produce high-speed devices based on their discovery.

"The ideal scenario is to achieve 100 percent surface conduction with a complete insulating state in the bulk," Xiu said. "Based on the current work, we are targeting high-performance transistors with power consumption that is much less than the conventional complementary metal-oxide semiconductors (CMOS) technology used typically in today's electronics."


Contact: Wileen Wong Kromhout
University of California - Los Angeles

Related biology news :

1. Genetic Engineering & Biotechnology News reports on growing role of molecular diagnostics
2. US Senate confirms Clemson University engineering Dean Esin Gulari to National Science Board
3. University success at national engineering awards
4. NJIT professor finds engineering technique to identify disease-causing genes
5. MIT: Mending broken hearts with tissue engineering
6. Stanley to Continue Biometrics In-Service Engineering Support for U.S. Army
7. Genetic Engineering & Biotechnology News reports on the trend toward predictive toxicogenomics
8. Engineering algae to make fuel instead of sugar
9. NTU undergrad is first Singapore champion of an internationally acclaimed engineering competition
10. Developer of advanced computing memory, father of biochemical engineering, and innovative engineering educators win highest engineering honors of 2009
11. Stevens receives $25,000 grant from the Engineering Information Foundation
Post Your Comments:
(Date:11/18/2015)... PHILADELPHIA , Nov. 18, 2015  As new ... in children, doctors and other healthcare providers face challenges ... counsel families and patients. In addition, as more children ... into a patient,s adulthood and old age. ... The Children,s Hospital of Philadelphia (CHOP) . ...
(Date:11/17/2015)... EASTON, Mass. , Nov. 17, 2015 ... a leader in the development and sale of broadly ... the worldwide life sciences industry, today announced it has ... of its $5 million Private Placement (the "Offering"), increasing ... to $4,025,000.  One or more additional closings are expected ...
(Date:11/11/2015)... Nov. 11, 2015   MedNet Solutions , an innovative ... clinical research, is pleased to announce that it will be ... (PCT) event, to be held November 17-19 in ... view live demonstrations of iMedNet , MedNet,s ... iMedNet has been able to deliver time and ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... Md. , Nov. 25, 2015  PharmAthene, Inc. ... Directors has adopted a stockholder rights plan (Rights Plan) ... net operating loss carryforwards (NOLs) under Section 382 of ... --> PharmAthene,s use of its NOLs ... "ownership change" as defined in Section 382 of the ...
(Date:11/25/2015)... 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:  AEZS; TSX: ... prospects remain fundamentally strong and highlights the following ... received DSMB recommendation to continue the ZoptEC Phase ... the final interim efficacy and safety data ... men with heavily pretreated castration- and Taxane-resistant prostate ...
(Date:11/24/2015)... 24, 2015  Asia-Pacific (APAC) holds the third-largest ... market. The trend of outsourcing to low-cost locations ... higher volume share for the region in the ... margins in the CRO industry will improve. ... ( ), finds that the market earned ...
(Date:11/24/2015)... , ... November 24, 2015 , ... ... healthy metabolism. But unless it is bound to proteins, copper is also toxic ... (NIH), researchers at Worcester Polytechnic Institute (WPI) will conduct a systematic study of ...
Breaking Biology Technology: