Technical / research - Page 7

Researchers from the University of Waterloo in Canada developed a new transfer and bonding method to deposit a flexible microLED array on plastic substrates.

The technique, referred to as a "paste-and-cut", starts with temporarily bonding the LEDs on a process/handle wafer onto a glass substrate (the paste step). The LEDs are then released (cut) to the flexible substrate. This approach allows the LED to be optimized and then combined with other materials.

Researchers from Seoul National University (SNU) in collaboration with KAIST, SAIT and the Korea Photonics Institute developed a new method to deposit MicroLEDs on sapphire nano-membranes which enables chip singulation without an etching process. This method can enable higher efficiency MicroLED devices.

The researchers say that this method improves the internal quantum efficiency (IQE) of the microLEDs by 44% compared to standard GaN microLEDs produced on regular planar substrates. The microLEDs also featured a reduced dislocation density (by 59.6%). According to their tests, the microLEDs provided 3.3X the photoluminescence compared to regular microLEDs.

Researchers from the University of Sheffield a new fabrication process for green InGaN microLEDs that achieves high brightness compact microLED arrays.

Today most green InGaN microLEDs are produced by combining a standard photolithography technique with subsequent dry-etching processes on a standard III-nitride LED wafer. The researchers found a way to avoid the dry-etching processes which damage the surface the resulting LEDs. In the new process, the InGaN stack is direectly grown within pre-patterned micro-hole arrays through a thin (500nm) SiO₂ layer serving as a GaN template over the epitaxial wafer.

MicroLED-Info and Perovskite-Info are happy to announce the 2020 edition of The Perovskite Handbook. This book is a comprehensive guide to perovskite materials, applications and industry, and it is now updated to January 2020 and lists recent developments and new companies, initiatives and research activities.

Perovskites are an exciting class of materials that feature a myriad of exciting properties. Perovskites are now entering the display market, with applications in quantum dots, LEDs, lasers and more.

Reading this book, you'll learn all about:

• Different perovskite materials, their properties and structure
• How perovskites can be made, tuned and used
• What kinds of applications perovskites are suitable for
• Perovskites Quantum Dots
• Perovskite solar cells, their merits and challenges
• Perovskites-based LEDs
• The state of the perovskite market, potential and future
   

iBeam Materials announced that it had successfully demonstrated the ability to produce high-performance GaN Field-Effect Transistors (FETs) directly on thin, flexible and rollable metal foil substrates.

This new technology complements iBeam's microLED deposition technology (demonstrated in the video above), and these FETs can be integrated with microLED chips in a side-by-side architecture. Both FETs and MicroLEDs are deposited on the flexible substrate without any transfer process.

Seoul Viosys and Seoul Semiconductors have jointly developed a new MicroLED technology, called Micro Clean LED that basically packages three separate LEDs (red, green and blue) into a single "one-single MicroLED pixel".

The idea is that these packaged colored pixels will be easier to transfer to the target substrate compared to the transfer of three different LEDs. The package itself does not contain any driver ICs.

Researchers from the Korea Advanced Institute of Science and Technology (KAIST) developed a new process that enables the fabrication of highly dense MicroLED displays - up to 63,500 PPI (!).

The technique involves stacking RGB LEDs in three dimensions and a semiconductor patterning process. Stacking LEDs one on top of the other creates color interference issues, and to overcome this the researchers deposited an insulating film between the layers. This also improved the efficiency of the microLED devices.

UK-based GaN-On-Si MicroLED microdisplay developer Plessey Semiconductor announced that it has successfully developed the world’s first GaN on Silicon-based Red LED.

Red LEDs are typically based on AlInGaP materia, or are color-converted from blue LEDs. These red LEDs limit the efficiency and the ability to create ultra-fine pitch sub pixels. Plessey says that InGaN red LEDs will also offer lower manufacturing costs, scalability to larger 200 mm or 300 mm wafers and better hot/cold factor over incumbent AlInGaP-based Red.

UK-based GaN-On-Si MicroLED microdisplay developer Plessey Semiconductor announced that it managed to deposit native blue and green microLEDs on the same wafer. Plessey’s new patented process forms microLEDs that exhibit high current density operation and long operational lifetime.

Plessey said that to achieve this important milestone they had to overcome several challenges - including a magnesium memory effect, diffusion from the p-type cladding of the lower junction into the upper junction and the requirement for the precise tuning of the thermal budget during the growth of the second junction to prevent indium phase separation in the blue active region.

The Fraunhofer IAP and Korea Electronics Technology Institute (KETI) have launched a joint research project to develop ink-jet printed quantum dots color filters for microLED displays.

The five-years CoCoMe (Color Converting MicroLeds) project aims to develop materials and processes to achieve high brightness microLEDs using quantum based color filters.