Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > UMD graphene photodetector offers better weapons detectors & scanners, telescopes to study dark energy

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

Illustration by Loretta Kuo and Michelle Groce, University of Maryland.

Abstract:
Innovation promises better biochemical weapons detection and body scanners, and new instruments for studying dark energy & the structure of the universe.

UMD graphene photodetector offers better weapons detectors & scanners, telescopes to study dark energy

College Park, MD | Posted on June 3rd, 2012

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 new 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 photo-detecting material.

####

For more information, please click here

Contacts:
Science Contact: Dr. Michael S. Fuhrer

Phone: (301) 405-6143

Copyright © University of Maryland

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Imaging

Raman Whispering Gallery Detects Nanoparticles September 1st, 2014

New analytical technology reveals 'nanomechanical' surface traits August 29th, 2014

Measure Both Elastic and Viscous Properties with AFM Using Asylum Research’s Exclusive AM-FM Viscoelastic Mapping Mode August 28th, 2014

Scientists craft atomically seamless, thinnest-possible semiconductor junctions August 26th, 2014

News and information

Raman Whispering Gallery Detects Nanoparticles September 1st, 2014

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Nanoscale assembly line August 29th, 2014

Physics

New technique uses fraction of measurements to efficiently find quantum wave functions August 28th, 2014

Creation of a Highly Efficient Technique to Develop Low-Friction Materials Which Are Drawing Attention in Association with Energy Issues August 26th, 2014

X-ray Laser Probes Tiny Quantum Tornadoes in Superfluid Droplets: SLAC Experiment Reveals Mysterious Order in Liquid Helium August 25th, 2014

Rice physicist emerges as leader in quantum materials research: Nevidomskyy wins both NSF CAREER Award and Cottrell Scholar Award August 20th, 2014

Graphene

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Graphene Structure Studied in Iran by Novel Method August 25th, 2014

Discoveries

Raman Whispering Gallery Detects Nanoparticles September 1st, 2014

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Nanoscale assembly line August 29th, 2014

Copper shines as flexible conductor August 29th, 2014

Announcements

Raman Whispering Gallery Detects Nanoparticles September 1st, 2014

Nanoscale assembly line August 29th, 2014

New analytical technology reveals 'nanomechanical' surface traits August 29th, 2014

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

Homeland Security

Watching Schrödinger's cat die (or come to life): Steering quantum evolution & using probes to conduct continuous error correction in quantum computers July 30th, 2014

Production of Toxic Gas Sensor Based on Nanorods July 28th, 2014

Nano-sized Chip "Sniffs Out" Explosives Far Better than Trained Dogs: TAU researcher's groundbreaking sensor detects miniscule concentrations of hazardous materials in the air July 23rd, 2014

Tiny laser sensor heightens bomb detection sensitivity July 19th, 2014

Military

Fonon Announces 3D Metal Sintering Technology: Emerging Additive Nano Powder Manufacturing Technology August 28th, 2014

New technique uses fraction of measurements to efficiently find quantum wave functions August 28th, 2014

Introducing the multi-tasking nanoparticle: Versatile particles offer a wide variety of diagnostic and therapeutic applications August 26th, 2014

Biomimetic photodetector 'sees' in color: Rice lab uses CMOS-compatible aluminum for on-chip color detection August 25th, 2014

Aerospace/Space

Fonon Announces 3D Metal Sintering Technology: Emerging Additive Nano Powder Manufacturing Technology August 28th, 2014

Nanodiamonds Are Forever: A UCSB professor’s research examines 13,000-year-old nanodiamonds from multiple locations across three continents August 27th, 2014

Creation of a Highly Efficient Technique to Develop Low-Friction Materials Which Are Drawing Attention in Association with Energy Issues August 26th, 2014

Thermal Block Coatings Developed in Iran Using Nanotechnology August 26th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE