Printer Friendly

Quantum wells as heat detectors.

Quantum wells as heat detectors

A quantum-well heat-detection device based on a simpler gallium-arsenide/gallium-aluminum arsenide structure is described in the July 25 APPLIED PHYSICS LETTERS by Barry Levine and colleagues from AT&T Bell Laboratories in Murray Hill, N.J. Today's best infrared (heat) detectors -- largely used by the military (as night scopes to view troops and weapons) and on remote-sensing satellites -- rely on mercury-cadmium-telluride semiconductors. While very sensitive, these are also difficult to make and reproduce, notes Federico Capasso, head of quantum phenomena and device research at Bell Labs and a manager of the quantum-well heat-detector project. In contrast, he says, the AT&T heat sensor is based on a common, easy-to-produce material.

The heart of the new photodetector is a crystalline superlattice containing 50 units -- each a 40-angstrom-wide quantum well whose sides are 300-angstrom barriers of aluminum-gallium arsenide. At the bottom of each well are a multitude of electrons. As a 10-micron wavelength photon enters the well, it excites an electron -- essentially kicking it up above the barrier and outside the well. At this higher energy level, the electron is unbound and free to "sail through the whole superlattice structure," Capasso exlains. Wells are refilled from a "reservoir" of electrons slowly tunneling through the crystal. Varying the well's width and its barrier composition will allow detection of up to 5-micron photons.

Although Capasso's group has been working on the 10-micron heat detector for only about one year, he says it "already starts to match the performance of detectors that have been out there for 20 years." Moreover, because it is based on the well-established gallium-arsenide semiconductor technology, he says, it offers the promise of costing less and for the first time making a 10-micron detector and the electronics for analyzing that signal out of the same chip.
COPYRIGHT 1988 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1988, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Publication:Science News
Date:Aug 13, 1988
Previous Article:Most sensitive photoelectric semiconductor.
Next Article:Awakenings in anesthesia: amid controversy, scientists move closer to understanding surgery's mysterious partner.

Related Articles
Experimenting with 40 trillion electron-volts: it takes hundred of physicists several years to design experimental detectors for the Superconducting...
Quantum baseball: a baseball analogy illuminates a paradox of quantum mechanics.
The signal value of noise: adding the right kind can amplify a weak signal.
Quantum cheating.
Instant transport: achieving quantum teleportation in the laboratory.
Watching washes out interference.
Unusual laser emits a band of light. (Beam Team).
NIST researchers develop revolutionary detector for quantum communications system. (News Briefs).
NIST photon number resolving detectors contribute to quantum key distribution.
Warming up to criticality: quantum change, one bubble at a time.

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters