Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Superlattice Structure Enables High Performance Infrared Imaging

30.05.2008
Scientists at the Center for Quantum Devices (CQD) in the McCormick School of Engineering at Northwestern University have demonstrated for the first time a high-performance infrared imager, based on a Type II superlattice, which looks at wavelengths 20 times longer than visible light.

Researchers at center, led by Manijeh Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science, say that such technology has the potential for broad applications in the detection of terrorist activities, such as use in night vision, target identification, and missile tracking.

Any object, including the human body, with a near-room temperature actively emits long wavelength (around 10 micron) infrared radiation (LWIR). Tracking this infrared radiation using high-speed infrared (IR) imagers would help to reveal thermal profiles of hidden targets or objects at night when no visible source is available. Such imagers also have potential use in medical applications where excessive heating or cooling in the body can indicate problems like inflammation, blood flow issues or even cancerous tissue.

In LWIR imaging applications, the dominant technologies are photodetectors based upon the HgCdTe (mercury cadmium telluride or MCT) material platform and the quantum well photoconductors (QWIP). Both of them have shown limitations that stimulated the research for alternative technologies. Type-II InAs/GaSb (indium arsenide/gallium antimonide) superlattices, first proposed by Nobel laureate Leo Esaki in 1973, became a potential for use in infrared detection in 1987. It wasn’t until semiconductor epitaxial growth techniques such as molecular beam epitaxy were sufficiently advanced in the 1990s that high-performance infrared photon detection based on these superlattices was fully demonstrated.

“The type-II superlattice will become the next generation infrared material replacing MCT technology,” says Razeghi. “MCT has many limitations, especially in the longer wavelength infrared range critical for missile detection.”

Razeghi’s research group has recently invented a new superlattice structure, called the M-structure, which boosted the performance of the type II superlattice to a new level. This new device structure is capable of detecting very low light intensity with high optical efficiency and exhibits an electrical noise level 10 times smaller than the original design. A LWIR 320x256 pixel focal plane array fabricated from this material has been able to differentiate temperature differences as low as 0.02 degrees Celsius. The camera was able to detect 74 percent of the incident photons, similar to other leading technologies.

Researchers recently presented their findings at the SPIE Photonics West Conference held in San Jose, CA on Jan. 19-24, 2008. This work was also published in the October 18, 2007 issue of the journal Applied Physics Letters.

The work performed at CQD has generated much interest in type-II superlattice research and has brought funding from the U.S. Missile Defense Agency, U.S. Air Force Research Laboratory, Office of Naval Research, and the Defense Advanced Research Projects Agency, as well as collaborations with Rockwell Scientific Company, Naval Research Laboratory, Airforce Research Laboratory, Jet Propulsion Laboratory, BAE, Lockheed, and Raytheon Company.

Kyle Delaney | EurekAlert!
Further information:
http://www.northwestern.edu

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>