Featured Research

from universities, journals, and other organizations

Scientists Propose Growing Better Semiconductor Crystals In Space

Date:
June 5, 2000
Source:
University Of Illinois At Urbana-Champaign
Summary:
Crystals grown in space may be the next big step toward improved semiconductor materials for use in next-generation communication systems and advanced computers.

CHAMPAIGN, Ill. -- Crystals grown in space may be the next big step toward improved semiconductor materials for use in next-generation communication systems and advanced computers.

Related Articles


Scientists and engineers who are trying to develop semiconductor "alloy crystals" -- special blends of germanium and silicon -- have a big problem on their hands. The crystals possess highly desirable thermoelectric and electro-optic properties, but they are nearly impossible to grow on Earth because of the effects of gravity.

"Germanium is about three times heavier than silicon, so it generally sinks to the bottom of the melt in the crucible, destroying the desired homogenous concentration in the crystal," said John Walker, a professor of mechanical and industrial engineering at the University of Illinois. "On Earth, gravity also presses the liquid against the walls of the container, resulting in the formation of numerous faults, dislocations and contact stresses in the growing crystal."

In the absence of gravity, however, the ingredients don't separate as readily and the molten material tends to pull away from the container shortly before solidifying, Walker said. "In experiments performed on the space shuttle, this 'detached growth' process has produced much better crystals."

Walker is working with scientists at Marshall Space Flight Center -- NASA's lead center for microgravity research in materials science -- to explore physical processes in space that are difficult to study on Earth. The group has proposed growing alloy crystals on the International Space Station.

"The pencil-thin crystals would be grown in special ampuls within magnetic damping furnaces on the space station," Walker said. "The magnetic fields would act as a brake, suppressing all movement in the molten material and thereby preventing the mixture from separating."

Walker has developed models to help optimize the benefits of using magnetic fields to control crystal growth. He also has devised methods for determining the distributions of the magnetic field and the electromagnetic force at different frequencies, and their effects on the melt motion.

"These crystals take up to 14 days to grow," Walker said. "It's a very slow and delicate process that must be precisely monitored and controlled. By controlling the melt motion with an externally applied magnetic field, we can produce a uniform distribution in the crystal."

While growing crystals in space will probably never be commercially viable, Walker and his colleagues hope to show that space-grown crystals consistently create better semiconductor materials.

"Then, once we understand the fundamental materials science, we can search for a way to reliably reproduce these crystals on Earth, in the presence of gravity," he said.

Walker will present his results at the NASA Microgravity Materials Science Conference, to be held June 6-8, at the Marshall Space Flight Center in Huntsville, Ala.


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "Scientists Propose Growing Better Semiconductor Crystals In Space." ScienceDaily. ScienceDaily, 5 June 2000. <www.sciencedaily.com/releases/2000/06/000602074630.htm>.
University Of Illinois At Urbana-Champaign. (2000, June 5). Scientists Propose Growing Better Semiconductor Crystals In Space. ScienceDaily. Retrieved April 18, 2015 from www.sciencedaily.com/releases/2000/06/000602074630.htm
University Of Illinois At Urbana-Champaign. "Scientists Propose Growing Better Semiconductor Crystals In Space." ScienceDaily. www.sciencedaily.com/releases/2000/06/000602074630.htm (accessed April 18, 2015).

Share This


More From ScienceDaily



More Space & Time News

Saturday, April 18, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

International Space Station Captures SpaceX Dragon Spacecraft

International Space Station Captures SpaceX Dragon Spacecraft

Reuters - News Video Online (Apr. 17, 2015) SpaceX&apos;s Dragon spacecraft reaches the International Space Station and is successfully captured by the station&apos;s robotic arm. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Planet Defence Conference Tackles Asteroid Threat

Planet Defence Conference Tackles Asteroid Threat

AFP (Apr. 17, 2015) Scientists gathered at a European Space Agency (ESA) facility outside Rome this week for the Planetary Defence Conference 2015 to discuss how to tackle the potential threat from asteroids hitting Earth. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
NASA Electric Rover Goes for a Spin

NASA Electric Rover Goes for a Spin

Reuters - Innovations Video Online (Apr. 17, 2015) NASA&apos;s prototype electric buggy could influence future space rovers and conventional cars. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
NASA’s MESSENGER Mercury Mission Is About To Crash Land

NASA’s MESSENGER Mercury Mission Is About To Crash Land

Newsy (Apr. 17, 2015) Rest in pieces, MESSENGER, knowing you gave us most of what we know about Mercury before you ran out of fuel and slammed into its surface at 8,750mph. 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