Featured Research

from universities, journals, and other organizations

Tiny Avalanche Photodiodes Target Bioterrorism Agents

Date:
September 14, 2005
Source:
Northwestern University
Summary:
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.

EVANSTON, Ill. --- After the anthrax attacks in the United States in2001 the threat of a larger and more deadly bioterrorism attack --perhaps from smallpox, plague or tularemia -- became very real. But theability to detect such biological agents and rapidly contain an attackis still being developed.

Related Articles


In a significant finding, researchers at Northwestern University'sCenter for Quantum Devices have demonstrated solar-blind avalanchephotodiodes (APDs) that hold promise for universal biological agentdetection. Once optimized, these sensitive detectors could be combinedwith the ultraviolet light-emitting diodes (LEDs) already pioneered bythe Center for Quantum Devices to create an inexpensive detectionsystem capable of identifying the unique spectral fingerprints of abiological agent attack.

The Northwestern team, led by center director Manijeh Razeghi, becamethe first to demonstrate 280 nanometer APDs. These devices, based onaluminum gallium nitride (AlGaN) compound semiconductors, have aphotocurrent gain of more than 700.

The tiny-sized APDs should be capable of efficient detection of lightwith near single photon precision. Previously, photomultiplier tubes(PMTs) were the only available technology in the short wavelength UVportion of the spectrum capable of this sensitivity. These fragilevacuum tube devices are expensive and bulky, hindering true systemsminiaturization.

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

The technology for the realization of solar-blind APDs is based on widebandgap AlGaN compound semiconductors. To date, no semiconductor-basedsolar-blind APDs have been reported. This is due to numerousdifficulties pertaining to the crystal growth of AlGaN compoundsemiconductors.

The major obstacle in demonstrating high performance solar-blind APDsis the high number of crystalline defects present in the AlGaNsemiconductor material. However, researchers at the Center for QuantumDevices have been able to realize high-quality AlGaN so as todemonstrate avalanche gain in the solar-blind region.

Northwestern's results were presented recently by Razeghi at the APDworkshop organized by Henryk Temkin, a new program manager at theDefense Advanced Research Projects Agency (DARPA).


Story Source:

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


Cite This Page:

Northwestern University. "Tiny Avalanche Photodiodes Target Bioterrorism Agents." ScienceDaily. ScienceDaily, 14 September 2005. <www.sciencedaily.com/releases/2005/09/050914104839.htm>.
Northwestern University. (2005, September 14). Tiny Avalanche Photodiodes Target Bioterrorism Agents. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2005/09/050914104839.htm
Northwestern University. "Tiny Avalanche Photodiodes Target Bioterrorism Agents." ScienceDaily. www.sciencedaily.com/releases/2005/09/050914104839.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
First Etihad Superjumbo Flight in December

First Etihad Superjumbo Flight in December

AFP (Dec. 18, 2014) The first flight of Etihad Airways' long-awaited Airbus A380 superjumbo will take place later in December, the Abu Dhabi carrier said Thursday, also announcing its first Boeing 787 Dreamliner route. Duration: 01:09 Video provided by AFP
Powered by NewsLook.com
Ford Expands Air Bag Recall Nationwide

Ford Expands Air Bag Recall Nationwide

Newsy (Dec. 18, 2014) The automaker added 447,000 vehicles to its recall list, bringing the total to more than 502,000. Video provided by Newsy
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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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