Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Pure red LEDs fulfill a primary goal

07.05.2020

Making pure red LEDs from nitride crystals is a goal that has so far frustrated engineers. However, these LEDs are vital for building the next generation of energy-efficient micro-LED displays to follow OLED displays and for creating lighting with color tuning. Now, for the first time, a team of electrical engineers at KAUST has succeeded in making these LEDs.

"Electrical engineers can already make bright LEDs using varying materials to produce different colors. But to improve display technologies, engineers must integrate the three primary color LEDs, red, green and blue, onto one chip," explains Daisuke Iida, an electrical engineer at KAUST.


To improve display technologies, engineers must integrate the three primary color LEDs, blue, green and red, onto one chip.

Credit: © 2020 KAUST


This MOCVD machine is the key technology needed to achieve bright red LEDs.

Credit: © 2020 KAUST

This means they need to find one material that is suitable for manufacturing all three colors. The material should be able to produce each color with high intensity, and ideally, it should have a high-power output, but use relatively little battery voltage.

The best candidates for generating all three colors are a family of compounds called nitride semiconductors. These are crystals containing nitrogen that in theory can be used to create LEDs that produce light with wavelengths between ultraviolet and infrared, which includes the entire visible spectrum. Engineers usually use gallium nitride to make blue and green LEDs, but they have struggled to make bright red LEDs with this crystal.

"Red vision has been almost impossible--other groups have only really succeeded in making orange, not apple red," says group leader, Kazuhiro Ohkawa. "Now, we have developed a crystal growth system to realize pure red LEDs."

Replacing a large portion of the gallium with the element indium gives the desired red, but it is hard to do because indium easily evaporates from the crystal. So Iida, Ohkawa and colleagues created a reactor with extra indium vapor above the crystal's surface, a process known as metalorganic vapor-phase deposition. This added pressure prevents the indium in the crystal from escaping. "This gives us a higher indium concentration at the surface," says Ohkawa. "That's our secret!"

But there was another hurdle to overcome. Indium is made of larger atoms than gallium, so when it is introduced, it creates defects in the crystal, degrading the quality of output light. The team's trick was to also add aluminum, which has small atoms. "The introduction of the small atoms reduces the strain on the crystal, resulting in fewer crystal defects," says Iida.

"Another advantage is that the LEDs operate at about half the voltage of its competitors," says Ohkawa. "This will give you a longer lifetime for batteries."

Media Contact

Carolyn Unck
carolyn.unck@kaust.edu.sa
966-054-470-0408

https://www.kaust.edu.sa/en 

Carolyn Unck | EurekAlert!
Further information:
https://discovery.kaust.edu.sa/en/article/965/pure-red-leds-fulfill-a-primary-goal
http://dx.doi.org/10.35848/1882-0786/ab7168

More articles from Power and Electrical Engineering:

nachricht Efficient, Economical and Aesthetic: Researchers Build Electrodes from Leaves
03.07.2020 | Leibniz-Institut für Photonische Technologien e. V.

nachricht Electrons in the fast lane
03.07.2020 | Max-Planck-Institut für Polymerforschung

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

Im Focus: ILA Goes Digital – Automation & Production Technology for Adaptable Aircraft Production

Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...

Im Focus: AI monitoring of laser welding processes - X-ray vision and eavesdropping ensure quality

With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.

Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

 
Latest News

Rising water temperatures could endanger the mating of many fish species

03.07.2020 | Life Sciences

Risk of infection with COVID-19 from singing: First results of aerosol study with the Bavarian Radio Chorus

03.07.2020 | Studies and Analyses

Efficient, Economical and Aesthetic: Researchers Build Electrodes from Leaves

03.07.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>