Fri, Feb 24, 2017 | updated 05:11 AM IST

Make way for brighter, more efficient green LEDs

Updated: Aug 01, 2016 15:58 IST

Washington D.C, Aug 1 (ANI): A team of researchers has come up with a new method for making brighter and more efficient green light-emitting diodes (LEDs).

Using an industry-standard semiconductor growth technique, researchers at the University of Illinois at Urbana Champaign created gallium nitride (GaN) cubic crystals grown on a silicon substrate that are capable of producing powerful green light for advanced solid-state lighting.

"This work is very revolutionary as it paves the way for novel green wavelength emitters that can target advanced solid-state lighting on a scalable CMOS-silicon platform by exploiting the new material, cubic gallium nitride," said researcher Can Bayram.

Bayram noted, "The union of solid-state lighting with sensing (e.g. detection) and networking (e.g. communication) to enable smart (i.e. responsive and adaptive) visible lighting, is further poised to revolutionize how we utilize light. And CMOS-compatible LEDs can facilitate fast, efficient, low-power, and multi-functional technology solutions with less of a footprint and at an ever more affordable device price point for these applications."

Typically, GaN forms in one of two crystal structures: hexagonal or cubic. Hexagonal GaN is thermodynamically stable and is by far the more conventional form of the semiconductor. However, hexagonal GaN is prone to a phenomenon known as polarization, where an internal electric field separates the negatively charged electrons and positively charged holes, preventing them from combining, which, in turn, diminishes the light output efficiency.

Until now, the only way researchers were able to make cubic GaN was to use molecular beam epitaxy, a very expensive and slow crystal growth method when compared to the widely used metal-organic chemical vapor deposition (MOCVD) method that Bayram used.

Bayram and his graduate student Richard Liu made the cubic GaN by using lithography and isotropic etching to create a U-shaped groove on Si (100). This non-conducting layer essentially served as a boundary that shapes the hexagonal material into cubic form.

"Our cubic GaN does not have an internal electric field that separates the charge carriers--the holes and electrons," explained Liu. "So, they can overlap and when that happens, the electrons and holes combine faster to produce light."

Enhanced green LEDs aren't the only application for Bayram's cubic GaN, which could someday replace silicon to make power electronic devices found in laptop power adapters and electronic substations, and it could replace mercury lamps to make ultra-violet LEDs that disinfect water.

The study appears in the journal Applied Physics Letters. (ANI)

Washington D.C. [USA], Feb. 23(ANI): NASA's Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water.

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Noida (Uttar Pradesh) [India], Feb.22 (ANI): Germany's Alexander von Humboldt (AvH) Foundation has handed over equipment worth € 20, 000 to Amity University for accelerating research initiatives.

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Washington D.C. [USA], Feb. 18 (ANI): To boost breeding of endangered poultry breeds, Briton researchers have come up with gene-editing techniques for the rare breeds to use them as surrogates that cannot produce their own chicks.

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Meet 'Bernardbowen'- the new minor planet

Updated: Feb 18, 2017 07:00 IST

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Washington D.C. [USA], Jan. 25 (ANI): A study finds that early identification of hearing loss in newborn due to a disease or physical abnormality by birth may help them in better language outcomes as they grow.

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New Delhi [India], Jan. 13 (ANI): New computer simulations have shown that tiny droplets of sulphuric acid resulted in long-lasting cooling, which was a likely contributor to the death of land-living dinosaurs.

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New human organ in digestive system discovered

Updated: Jan 05, 2017 06:27 IST

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How do conch shells have such huge variety?

Updated: Jan 04, 2017 05:52 IST

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Washington D.C. [USA], Dec. 27 (ANI): Researchers in the United States have found that an emotional experience, which persists for over 20 to 30 minutes, can influence how you remember future experiences.

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