Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tiny avalanche photodiodes target bioterrorism agents

14.09.2005


After the anthrax attacks in the United States in 2001 the threat of a larger and more deadly bioterrorism attack -- perhaps from smallpox, plague or tularemia -- became very real. But the ability to detect such biological agents and rapidly contain an attack is still being developed.



In a significant finding, researchers at Northwestern University’s Center for Quantum Devices have demonstrated solar-blind avalanche photodiodes (APDs) that hold promise for universal biological agent detection. Once optimized, these sensitive detectors could be combined with the ultraviolet light-emitting diodes (LEDs) already pioneered by the Center for Quantum Devices to create an inexpensive detection system capable of identifying the unique spectral fingerprints of a biological agent attack.

The Northwestern team, led by center director Manijeh Razeghi, became the first to demonstrate 280 nanometer APDs. These devices, based on aluminum gallium nitride (AlGaN) compound semiconductors, have a photocurrent gain of more than 700.


The tiny-sized APDs should be capable of efficient detection of light with near single photon precision. Previously, photomultiplier tubes (PMTs) were the only available technology in the short wavelength UV portion of the spectrum capable of this sensitivity. These fragile vacuum tube devices are expensive and bulky, hindering true systems miniaturization.

The APD technology may see further use in the deployment of systems for secure battlefield communication. Wavelengths around 280 nanometers are referred to as the solar-blind region; in this region, the UV light is filtered out by the ozone layer providing for a naturally low background signal. Solar-blind APDs are intrinsically able to take advantage of this low background level, while PMTs must use external filters to become solar-blind. This makes secure battlefield communication possible utilizing a combination of compact, inexpensive UV LEDs and UV APDs both developed at the Center for Quantum Devices.

The technology for the realization of solar-blind APDs is based on wide bandgap AlGaN compound semiconductors. To date, no semiconductor-based solar-blind APDs have been reported. This is due to numerous difficulties pertaining to the crystal growth of AlGaN compound semiconductors.

The major obstacle in demonstrating high performance solar-blind APDs is the high number of crystalline defects present in the AlGaN semiconductor material. However, researchers at the Center for Quantum Devices have been able to realize high-quality AlGaN so as to demonstrate avalanche gain in the solar-blind region.

Northwestern’s results were presented recently by Razeghi at the APD workshop organized by Henryk Temkin, a new program manager at the Defense Advanced Research Projects Agency (DARPA).

Megan Fellman | EurekAlert!
Further information:
http://www.northwestern.edu

More articles from Physics and Astronomy:

nachricht Breaking the optical bandwidth record of stable pulsed lasers
24.01.2017 | Institut national de la recherche scientifique - INRS

nachricht European XFEL prepares for user operation: Researchers can hand in first proposals for experiments
24.01.2017 | European XFEL GmbH

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: Scientists spin artificial silk from whey protein

X-ray study throws light on key process for production

A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Breaking the optical bandwidth record of stable pulsed lasers

24.01.2017 | Physics and Astronomy

Choreographing the microRNA-target dance

24.01.2017 | Life Sciences

Spanish scientists create a 3-D bioprinter to print human skin

24.01.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>