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 Researchers observe charge-stripe crystal phase in an insulating cuprate
18.12.2018 | Boston College

nachricht Physicists studied the influence of magnetic field on thin film structures
18.12.2018 | Immanuel Kant Baltic Federal 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: Data storage using individual molecules

Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.

Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Physicists found a correlation between the structure and magnetic properties of ceramics

18.12.2018 | Physics and Astronomy

Unique insights into an exotic matter state

18.12.2018 | Physics and Astronomy

Physicists studied the influence of magnetic field on thin film structures

18.12.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>