LEDs ♦ news digest less than 10% percent of world production in 2011.
“Leadership in innovation is key to developing a sustainable advantage for European industry and we need to build on the scientific excellence in Europe to turn great ideas into globally competitive technologies and related manufacturing,” comments Carlo Bozotti, President and Chief Executive Officer of STMicroelectronics.
“With traditional strengths in analogue and power as well as more recent innovations in technologies, companies in Europe have the capability to continue to lead the development of the next wave of electronic products. The actions outlined in the Commission’s Communication demonstrate a clear commitment to Europe’s future,” adds Bozotti.
Hendrik Abma, Director-General of ESIA, says, “ESIA welcomes the ambition and vision of the European Commission’s strategy. ESIA has consistently underlined the importance of the European semiconductor industry to the competitiveness and vitality of the European economy, as well as to tackling the grand societal challenges, such as energy efficiency and aging populations.”
ESIA looks forward to the full implementation of the European Commission’s strategy for micro- and nanoelectronic components and systems. ESIA is fully aware that the strategy’s successful execution requires significant alignments among all stakeholders.
New family of tiny crystals glow bright in LED lights
Scientists are using X-ray diffraction to further understand crystals that could improve warm-white LED performance
Minuscule crystals that glow different colours may be the missing ingredient for white LED lighting that illuminates homes and offices as effectively as natural sunlight.
LEDs offer substantial energy savings over incandescent and fluorescent lights and are easily produced in single colours such as red or green commonly used in traffic lights or children’s toys.
Developing an LED that emits a broad spectrum of warm white light on par with sunlight has proven tricky. However. LEDs, which produce light by passing electrons through a semiconductor material, are often coupled with phosphors that glow when excited by radiation from the LED.
“But it’s hard to get one phosphor that makes the broad range of colours needed to replicate the sun,” notes John Budai, a scientist in Oak Ridge National Laboratory’s (ORNL’s) Materials Science and Technology division. “One approach to generating warm-white light is to hit a mixture of phosphors with ultraviolet radiation from an LED to stimulate many colours needed for white light.”
Budai is working with a team of scientists from University of Georgia and Oak Ridge and Argonne national laboratories to understand a new group of crystals that might yield the right blend of colours for white LEDs as well as other uses.
Zhengwei Pan’s group at UGA grew the nanocrystals using europium oxide and aluminium oxide powders as the source materials because the rare-earth element europium is known to be a dopant, or additive, with good phosphorescent properties.
“What’s amazing about these compounds is that they glow in lots of different colours - some are orange, purple, green or yellow,” Budai explains. “The next question became: why are they different colours? It turns out that the atomic structures are very different.”
Budai has been studying the atomic structure of the materials using x-rays from Argonne’s Advanced Photon Source. Two of the three types of crystal structures in the group of phosphors had never been seen before, which can probably be attributed to the crystals’ small size, Budai claims.
“Only the green ones were a known crystal structure,” Budai says. “The other two, the yellow and blue, don’t grow in big crystals; they only grow with these atomic arrangements in these tiny nanocrystals. That’s why they have different photoluminescent properties.”
X-ray diffraction analysis is helping Budai and his collaborators work out how the atoms are arranged in each of the different crystal types. The different-coloured
June 2013
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