Featured Research

from universities, journals, and other organizations

Faster, more sensitive photodetector created by tricking graphene

Date:
June 5, 2012
Source:
University of Maryland
Summary:
Researchers have developed a highly sensitive detector of infrared light that can be used in applications ranging from detection of chemical and biochemical weapons from a distance and better airport body scanners to chemical analysis in the laboratory and studying the structure of the universe through new telescopes.

Electrons in bilayer graphene are heated by a beam of light.
Credit: Illustration by Loretta Kuo and Michelle Groce, University of Maryland.

Researchers at the Center for Nanophysics and Advanced Materials of the University of Maryland have developed a new type of hot electron bolometer a sensitive detector of infrared light, that can be used in a huge range of applications from detection of chemical and biochemical weapons from a distance and use in security imaging technologies such as airport body scanners, to chemical analysis in the laboratory and studying the structure of the universe through improved telescopes.

The UMD researchers, led by Research Associate Jun Yan and Professors Michael Fuhrer and Dennis Drew, developed the bolometer using bilayer graphene--two atomic-thickness sheets of carbon. Due to graphene s unique properties, the bolometer is expected to be sensitive to a very broad range of light energies, ranging from terahertz frequencies or submillimeter waves through the infrared to visible light.

The graphene hot electron bolometer is particularly promising as a fast, sensitive, and low-noise detector of submillimeter waves, which are particularly difficult to detect. Because these photons are emitted by relatively cool interstellar molecules, submillimeter astronomy studies the early stages of formation of stars and galaxies by observing these interstellar clouds of molecules. Sensitive detectors of submillimeter waves are being sought for new observatories that will determine the redshifts and masses of very distant young galaxies and enable studies of dark energy and the development of structure in the universe.

The Maryland team s findings are published in the June 3 issue of Nature Nanotechnology.

Most photon detectors are based on semiconductors. Semiconductors are materials which have a range of energies that their electrons are forbidden to occupy, called a band gap . The electrons in a semiconductor can absorb photons of light having energies greater than the band gap energy, and this property forms the basis of devices such as photovoltaic cells.

Graphene, a single atom-thick plane of graphite, is unique in that is has a bandgap of exactly zero energy; graphene can therefore absorb photons of any energy. This property makes graphene particularly attractive for absorbing very low energy photons (terahertz and infrared) which pass through most semiconductors. Graphene has another attractive property as a photon absorber: the electrons which absorb the energy are able to retain it efficiently, rather than losing energy to vibrations of the atoms of the material. This same property also leads to extremely low electrical resistance in graphene.

University of Maryland researchers exploited these two properties to devise the hot electron bolometer. It works by measuring the change in the resistance that results from the heating of the electrons as they absorb light.

Normally, graphene s resistance is almost independent of temperature, unsuitable for a bolometer. So the Maryland researchers used a special trick: when bilayer graphene is exposed to an electric field it has a small band gap, large enough that its resistance becomes strongly temperature dependent, but small enough to maintain its ability to absorb low energy infrared photons.

The researchers found that their bilayer graphene hot electron bolometer operating at a temperature of 5 Kelvin had comparable sensitivity to existing bolometers operating at similar temperatures, but was more than a thousand times faster. They extrapolated the performance of the graphene bolometer to lower temperature and found that it may beat all existing technologies.

Some challenges remain. The bilayer graphene bolometer has a higher electrical resistance than similar devices using other materials which may make it difficult to use at high frequencies. Additionally, bilayer graphene absorbs only a few percent of incident light. But the Maryland researchers are working on ways to get around these difficulties with new device designs, and are confident that a graphene has a bright future as a photodetecting material.


Story Source:

The above story is based on materials provided by University of Maryland. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jun Yan, M-H. Kim, J. A. Elle, A. B. Sushkov, G. S. Jenkins, H. M. Milchberg, M. S. Fuhrer, H. D. Drew. Dual-gated bilayer graphene hot-electron bolometer. Nature Nanotechnology, 2012; DOI: 10.1038/nnano.2012.88

Cite This Page:

University of Maryland. "Faster, more sensitive photodetector created by tricking graphene." ScienceDaily. ScienceDaily, 5 June 2012. <www.sciencedaily.com/releases/2012/06/120605102842.htm>.
University of Maryland. (2012, June 5). Faster, more sensitive photodetector created by tricking graphene. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2012/06/120605102842.htm
University of Maryland. "Faster, more sensitive photodetector created by tricking graphene." ScienceDaily. www.sciencedaily.com/releases/2012/06/120605102842.htm (accessed July 29, 2014).

Share This




More Matter & Energy News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Baluchistan Mining Eyes an Uncertain Future

Baluchistan Mining Eyes an Uncertain Future

AFP (July 29, 2014) Coal mining is one of the major industries in Baluchistan but a lack of infrastructure and frequent accidents mean that the area has yet to hit its potential. Duration: 01:58 Video provided by AFP
Powered by NewsLook.com
Easier Nuclear Construction Promises Fall Short

Easier Nuclear Construction Promises Fall Short

AP (July 29, 2014) The U.S. nuclear industry started building its first new plants using prefabricated Lego-like blocks meant to save time and prevent the cost overruns that crippled the sector decades ago. So far, it's not working. (July 29) Video provided by AP
Powered by NewsLook.com
Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Newsy (July 28, 2014) Stanford University published its findings for a "pure" lithium ion battery that could have our everyday devices and electric cars running longer. Video provided by Newsy
Powered by NewsLook.com
The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
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