Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Materials could make for super LEDs, solar cells, computer chips

03.12.2003


Engineers at Ohio State University have overcome a major barrier in the manufacture of high quality light emitting devices and solar cell materials.


Engineers at Ohio State University have built bright light-emitting diodes (LEDs) on silicon substrates. One such LED is shown here. The new LEDs have a display quality comparable to that of traditional LEDs. Photo courtesy of Ohio State University.



Steven Ringel, professor of electrical engineering, and his colleagues have created special hybrid materials that are virtually defect-free -- an important first step for making ultra-efficient electronics in the future.

The same technology could also lead to faster, less expensive computer chips.


Ringel directs Ohio State’s Electronic Materials and Devices Laboratory, where he and his staff grow thin films of “III-V” semiconductors -- materials made from elements such as gallium and arsenic, which reside in groups III and V of the chemical periodic table.

Because III-V materials absorb and emit light much more efficiently than silicon, these materials could bridge the gap between traditional silicon computer chips and light-related technologies, such as lasers, displays, and fiber optics.

Researchers have tried for years to combine III-V materials with silicon, but only with limited success. Now that Ringel has succeeded in producing the combination with record quality, he has set his sights on a larger goal.

“Ultimately, we’d like to develop materials that will let us integrate many different technologies on a single platform,” Ringel said.

Key to Ringel’s strategy is the idea of a “virtual substrate” -- a generic chip-like surface that would be compatible with many different kinds of technologies, and could easily be tailored to suit different applications.

Ohio State graduate student Ojin Kwon reported the project’s latest results December 2 at the Materials Research Society meeting in Boston. Other coauthors include graduate student John Boeckl, also of Ohio State; and postdoctoral researcher Minjoo Lee, graduate student Arthur Pitera, and professor Eugene Fitzgerald, all of the Massachusetts Institute of Technology.

Ringel’s current materials design consists of a substrate of silicon topped with III-V materials such as gallium and arsenide, with hybrid silicon-germanium layers sandwiched in-between. The substrate is 0.7 millimeters thick, while the gallium arsenide layer is only 3 micrometers -- millionths of a meter -- thick.

Other labs have experimented with III-V materials grown on silicon, but none have been able to reduce defect levels below a critical level that would enable devices like light emitting diodes and solar cells to be achieved, Ringel said.

Defects occur when the thin layers of atoms in a film aren’t lined up properly. Small mismatches between layers rob the material of its ability to transmit electrical charge efficiently.

Ringel and his colleagues grew films of III-V semiconductors with a technique known as molecular beam epitaxy, in which evaporated molecules of a substance settle in thin layers on the surface of the silicon-germanium alloy. They then used techniques such as transmission electron microscopy to search for defects.

Defects are missing or misplaced atoms that trap electrons within the material, Ringel explained. That’s why engineers typically measure the quality of a solar cell material in terms of carrier lifetime -- the length of time an electron can travel freely through a material without falling into a defect.

Other experimental III-V materials grown on silicon have achieved carrier lifetimes of about two nanoseconds, or two billionths of a second. Ringel’s materials have achieved carrier lifetimes in excess of 10 nanoseconds.

The engineers have crafted the III-V material into one-square-inch versions of solar cells in the laboratory, and achieved 17 percent efficiency at converting light to electricity. They have also built bright light-emitting diodes (LEDs) on silicon substrates that have a display quality comparable to that of traditional LEDs.

The next phase in this research will carry Ringel’s materials into space, as part of NASA’s Materials International Space Station Experiment (MISSE). An international partner spacecraft will deliver samples of the materials to the space station so they can be tested and possibly developed for use in future spacecraft.

This work was funded by the Army Research Office and the National Science Foundation.


Contact: Steven Ringel, (614) 292-6904; Ringel.1@osu.edu
Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu

Pam Frost Gorder | OSU
Further information:
http://researchnews.osu.edu/archive/35led.htm

More articles from Materials Sciences:

nachricht New Multiferroic Materials from Building Blocks
29.09.2016 | National Institute for Materials Science

nachricht Silicon Fluorescent Material Developed Enabling Observations under a Bright “Biological Optical Window”
29.09.2016 | National Institute for Materials Science

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

 
Latest News

New Multiferroic Materials from Building Blocks

29.09.2016 | Materials Sciences

Silicon Fluorescent Material Developed Enabling Observations under a Bright “Biological Optical Window”

29.09.2016 | Materials Sciences

X-shape Bio-inspired Structures

29.09.2016 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>