Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

High-Speed Transistor Channel Developed Using a Core-Shell Nanowire Structure

18.01.2016

Research groups in Japan and the U.S. jointly developed a double-layered nanowire, consisting of a germanium core and a silicon shell, which is a promising material for high-speed transistor channels. This is a significant step toward the realization of three-dimensional transistors capable of high integration faster than conventional transistors.

A research group led by Naoki Fukata, International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), and a research group at Georgia Institute of Technology jointly developed a double-layered (core-shell) nanowire, consisting of a germanium (Ge) core and a silicon (Si) shell, which is a promising material for high-speed transistor channels.


Figure 1: Schematic of a vertical transistor and an expanded view of its core-shell nanowire part.

Copyright : National Institute for Materials Science


Figure 2. An EDX (energy-dispersive X-ray spectroscopy) image of a Ge/Si core-shell nanowire created by a CVD process. (Red, Si area; blue, Ge area.)

Copyright : National Institute for Materials Science

In addition, the groups verified that the Si layer, which was doped with impurities, and the Ge layer, which transports carriers, were not intermixed, and that carriers were generated in the Ge layer. These results suggest that the new nanowire may effectively suppress the impurity scattering, which had been a problem with conventional nanowires, thereby taking a major step toward the realization of a next-generation high-speed transistor.

Regarding the development of two-dimensional metal-oxide-semiconductor field-effect transistors (MOSFETs), which are now widely used, it was pointed out that efforts to miniaturize the MOSFET using conventional technology had reached the limit.

To deal with this issue, the development of a three-dimensional vertical transistor, instead of a two-dimensional transistor, was proposed as a new approach to realize high integration (Figure 1). The use of semiconducting nanowires as channels—the most vital part of the 3-D transistor—had been suggested. However, there was a problem with this method: in nanowires with a diameter of less than 20 nm, impurities doped into the nanowires to generate carriers caused the carriers to scatter, which in turn decreased their mobility.

By developing nanowires consisting of a Ge core and a Si shell, the research groups succeeded in creating high mobility channels capable of separating impurity-doped regions from carrier transport regions, thereby suppressing impurity scattering. The groups also successfully verified the performance of the channels.

Carriers are generated in the Si shell of the nanowires, introduced into the Ge core. Because carrier mobility is higher in the Ge layer than in the Si layer, this nanowire structure increases carrier mobility. In addition, this structure also suppresses the effect of surface scattering, which occurs commonly in conventional nanowires. Furthermore, the groups verified that the concentration of carriers can be controlled by the amount of doping.

Because the creation of the core-shell structure requires only simple materials—silicon and germanium, it is feasible to manufacture the nanowires at low cost. In future studies, we plan to actually construct devices employing the core-shell structure, and assess their potential as high-speed devices by evaluating their characteristics and performance.

This study was conducted as a part of the research project titled “Control of carrier transport by selective doping of core-shell heterojunction nanowires” (Naoki Fukata, principal investigator) funded by the Japan Society for the Promotion of Science’s Grants-in-Aid for Scientific Research (A) program, and the NIMS 3rd Mid-Term Program project on chemical nanotechnology.

(This study was published in ACS NANO on Nov.11,2015: Naoki Fukata, Mingke Yu, Wipakorn Jevasuwan, Toshiaki Takei, Yoshio Bando, Wenzhuo Wu, and Zhong Lin Wang: Clear experimental demonstration of hole gas accumulation in Ge/Si core-shell nanowires[DOI: 10.1021/acsnano.5b05394])


Associated links
Original article by National Institute for Materials Science

Mikiko Tanifuji | Research SEA
Further information:
http://www.researchsea.com

More articles from Materials Sciences:

nachricht Argon is not the 'dope' for metallic hydrogen
24.03.2017 | Carnegie Institution for Science

nachricht Researchers make flexible glass for tiny medical devices
24.03.2017 | Brigham Young University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>