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

New bandgap boundaries could boost electronics

Photonics Spectra
Apr 2012
Ashley N. Paddock,

A new layer-by-layer growth technique that reduces the bandgap of complex metal oxides by 30 percent could improve the performance of solar cells, LEDs, displays and other electronic devices.

For years, complex transition metal oxides have held promise for a variety of information and energy applications, but the challenge has been to devise a method to reduce bandgaps of those insulators without compromising the material’s useful physical properties.

The bandgap, a major factor in determining electrical conductivity in a material, directly determines the upper wavelength limit of light absorption. Wide bandgap tunability is highly desirable for optoelectronic devices and energy materials.

Ho Nyung Lee of Oak Ridge National Laboratory developed the layer-by-layer growth technique. For his achievement, he received the Presidential Early Career Award for Scientists and Engineers. He and his colleagues then used the method to achieve a 30 percent reduction in the bandgap of complex metal oxides, surpassing previous accomplishments of 6 percent – or 0.2 eV – and opening the door to new approaches to controlling bandgap in complex oxide materials.

“Our approach to tuning bandgaps is based on atomic-scale growth control of complex oxide materials, yielding novel artificial materials that do not exist in nature,” Lee said. “This ‘epitaxy’ technique can be used to design entirely new materials or to specifically modify the composition of thin-film crystals with subnanometer accuracy.”

ORNL’s materials scientists developed a synthesis strategy for discovering novel complex oxide thin films for stronger solar light absorption. Courtesy of ORNL.

With this discovery, the potential exists for oxides with band-gaps to be continuously controlled over 1 eV by site-specific alloying developed by the ORNL team.

“This work exemplifies how basic research can provide technical breakthroughs that will result in vastly improved energy technologies,” said Michelle Buchanan, associate lab director for ORNL’s Physical Sciences Directorate.

A patent is pending for the technology. The research was funded initially by the Laboratory Directed Research and Development program and later by the US Department of Energy’s Office of Science. Optical measurements were performed in part at the Center for Nanophase Materials Sciences, a DOE-BES user facility at ORNL.

The findings were outlined in Nature Communications (doi: 10.1038/ncomms1690).

In a semiconductor material, the minimum energy necessary for an electron to transfer from the valence band into the conduction band, where it moves more freely.
Americasbandgapbandgap boundariesBasic ScienceCenter for Nanophase Materials SciencesCommunicationscomplex metal oxidesConsumerDepartment of EnergyDisplaysDOEDOE-BESenergyepitaxy techniqueHo Nyung LeeLaboratory Directed Research and Development programlight emitting diodeslight sourcesMichelle BuchananOak Ridge National LaboratoryOffice of ScienceORNLPhysical Sciences DirectoratePresidential Early Career Award for Scientists and EngineersResearch & Technologysolar cellssubnanometer accuracyTech PulseTennesseethin film crystalsLEDs

Terms & Conditions Privacy Policy About Us Contact Us
back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2018 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.