Featured Research

from universities, journals, and other organizations

Lighting the way to graphene-based devices

Date:
May 16, 2014
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
A technique whereby semiconductors made from graphene and boron nitride can be charge-doped to alter their electronic properties using only visible light has been demonstrated by researchers. Graphene continues to reign as the next potential superstar material for the electronics industry, a slimmer, stronger and much faster electron conductor than silicon.

Semiconductors made from graphene and boron nitride can be charge-doped using light. When the GBN heterostructure is exposed to light (green arrows), positive charges move from the graphene layer (purple) to boron nitride layer (blue).
Credit: Image courtesy of DOE/Lawrence Berkeley National Laboratory

Graphene continues to reign as the next potential superstar material for the electronics industry, a slimmer, stronger and much faster electron conductor than silicon. With no natural energy band-gap, however, graphene's superfast conductance can't be switched off, a serious drawback for transistors and other electronic devices. Various techniques have been deployed to overcome this problem with one of the most promising being the integration of ultrathin layers of graphene and boron nitride into two-dimensional heterostructures. As conductors, these bilayered hybrids are almost as fast as pure graphene, plus they are well-suited for making devices. However, tailoring the electronic properties of graphene boron nitride (GBN) heterostructures has been a tricky affair, involving chemical doping or electrostatic-gating -- until now.

Researchers with Berkeley Lab and the University of California (UC) Berkeley have demonstrated a technique whereby the electronic properties of GBN heterostructures can be modified with visible light. Feng Wang, a condensed matter physicist with Berkeley Lab's Materials Sciences Division and UC Berkeley's Physics Department, as well as an investigator for the Kavli Energy NanoSciences Institute at Berkeley, led a study in which photo-induced doping of GBN heterostructures was used to create p-n junctions and other useful doping profiles while preserving the material's remarkably high electron mobility.

"We've demonstrated that visible light can induce a robust writing and erasing of charge-doping in GBN heterostructures without sacrificing high carrier mobility," Wang says. "The use of visible light gives us incredible flexibility and, unlike electrostatic gating and chemical doping, does not require multi-step fabrication processes that reduce sample quality. Additionally, different patterns can be imparted and erased at will, which was not possible with doping techniques previously used on GBN heterostructures."

Graphene is a single layer of carbon atoms arranged in a hexagonal lattice. Boron nitride is a layered compound that features a similar hexagonal lattice -- in fact hexagonal boron nitride is sometimes referred to as "white graphene." Bound together by the relatively weak intermolecular attraction known as the van der Waals force, GBN heterostructures have shown high potential to serve as platforms not only for high-electron-mobility transistors, but also for optoelectronic applications, including photodetectors and photovoltaic cells. The key to future success will be the ability to dope these materials in a commercially scalable manner. The photo-induced modulation doping technique developed by Wang and a large team of collaborators meets this requirement as it is comparable to the photolithography schemes widely used today for mass production in the semiconductor industry. Illumination of a GBN heterostructure even with just an incandescent lamp can modify electron-transport in the graphene layer by inducing a positive-charge distribution in the boron nitride layer that becomes fixed when the illumination is turned off.

"We've shown show that this photo-induced doping arises from microscopically coupled optical and electrical responses in the GBN heterostructures, including optical excitation of defect transitions in boron nitride, electrical transport in graphene, and charge transfer between boron nitride and graphene," Wang says. "This is analogous to the modulation doping first developed for high-quality semiconductors."

While the photo-induced modulation doping of GBN heterostructures only lasted a few days if the sample was kept in darkness -- further exposure to light erased the effect -- this is not a concern as Wang explains.

"A few days of modulation doping are sufficient for many avenues of scientific inquiry, and for some device applications, the rewritability we can provide is needed more than long term stability," he says. "For the moment, what we have is a simple technique for inhomogeneous doping in a high-mobility graphene material that opens the door to novel scientific studies and applications."

A paper on this research has been published in the journal Nature Nanotechnology entitled "Photoinduced doping in heterostructures of graphene and boron nitride."


Story Source:

The above story is based on materials provided by DOE/Lawrence Berkeley National Laboratory. The original article was written by Lynn Yarris. Note: Materials may be edited for content and length.


Journal Reference:

  1. L. Ju, J. Velasco, E. Huang, S. Kahn, C. Nosiglia, Hsin-Zon Tsai, W. Yang, T. Taniguchi, K. Watanabe, Y. Zhang, G. Zhang, M. Crommie, A. Zettl, F. Wang. Photoinduced doping in heterostructures of graphene and boron nitride. Nature Nanotechnology, 2014; 9 (5): 348 DOI: 10.1038/nnano.2014.60

Cite This Page:

DOE/Lawrence Berkeley National Laboratory. "Lighting the way to graphene-based devices." ScienceDaily. ScienceDaily, 16 May 2014. <www.sciencedaily.com/releases/2014/05/140516203340.htm>.
DOE/Lawrence Berkeley National Laboratory. (2014, May 16). Lighting the way to graphene-based devices. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/2014/05/140516203340.htm
DOE/Lawrence Berkeley National Laboratory. "Lighting the way to graphene-based devices." ScienceDaily. www.sciencedaily.com/releases/2014/05/140516203340.htm (accessed September 17, 2014).

Share This



More Matter & Energy News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

Newsy (Sep. 16, 2014) MIT developed a robot modeled after a cheetah. It can run up to speeds of 10 mph, though researchers estimate it will eventually reach 30 mph. Video provided by Newsy
Powered by NewsLook.com
Manufacturer Prints 3-D Car In Record Time

Manufacturer Prints 3-D Car In Record Time

Newsy (Sep. 15, 2014) Automobile manufacturer Local Motors created a drivable electric car using a 3-D printer. Printing the body only took 44 hours. Video provided by Newsy
Powered by NewsLook.com
Refurbished New York Subway Tunnel Unveiled After Sandy Damage

Refurbished New York Subway Tunnel Unveiled After Sandy Damage

Reuters - US Online Video (Sep. 15, 2014) New York officials unveil subway tunnels that were refurbished after Superstorm Sandy. Nathan Frandino reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins