Search Menu
Photonics Media Photonics Buyers' Guide Photonics EDU Photonics Spectra BioPhotonics EuroPhotonics Industrial Photonics Photonics Showcase Photonics ProdSpec Photonics Handbook
More News
Email Facebook Twitter Google+ LinkedIn Comments

Best Lasers May Be Misanthropes

Photonics Spectra
Oct 1999
Stephanie A. Weiss

Quantum dots are antisocial, and that's good news for Sandia National Laboratory researchers who want to make better lasers.

Quantum dots, atomic islands of material that appear on semiconductor thin films, can produce laser light. Their very small size and 3-D nature modify the fundamental photonic properties of the film. Packing more dots into a small area makes a more intense light source, and shrinking the dots reduces their wavelength into some spectral regions that semiconductor lasers can't easily reach otherwise.

The problem with quantum dots is that it's hard to create dots of uniform size and composition in orderly rows. Sandia scientist Jerry Floro has been working with researchers at the Univer-sity of Illinois at Urbana-Champaign and at Brown University in Providence, R.I., to better understand how and why dots form as they do.

Using a patented probe, the researchers "watched" while they deposited atomic layers of silicon germanium. The first 10 layers went down smoothly, but as they added more layers, pyramids buckled up from the substrate. With additional layers, the pyramids organized themselves into evenly spaced rows, occasionally "coarsening," or absorbing, neighboring dots.

The process revealed an ideal quantum dot repellant: another quantum dot. The self-organization step resembles what happens when strangers meet in an elevator: They line up in rows, each standing a little taller and thinner than usual to avoid touching a neighbor. If too many people enter this quantum elevator, individuals steadfastly maintain their space -- by killing and eating their neighbors.

Floro acknowledged that silicon germanium is not a good laser material; the group's next step is to determine how well its general physics will apply to laser materials such as indium gallium arsenide.

Basic ScienceResearch & Technologysemiconductor lasersTech Pulselasers

Terms & Conditions Privacy Policy About Us Contact Us
back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2019 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA,

Photonics Media, Laurin Publishing
x Subscribe to Photonics Spectra magazine - FREE!
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.