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Technical / research

Plessey developed a process to deposit native green and blue microLEDs on the same wafer

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 native green and blue microLEDs wafer photo

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.

Read the full story Posted: Oct 06, 2019

Researchers develop a laser-driven programmable non-contact transfer printing technique

Researchers at Zhejiang University developed a laser-driven programmable non-contact transfer printing technique that could be applicable to the transfer of Micro-LED chips. The researchers used an innovative design based on an active elastomeric micro-structured stamp with tunable adhesion.

Zhejiang University laser-driven non-contact transfer-printing technique process

The tunable adhesive used in this technique features cavities filled with air and encapsulated by a micro-patterned surface membrane, used in easily available sandpapers. The micro-patterned surface membrane can be inflated dynamically to control the interfacial adhesion by heating the air in cavities.

Read the full story Posted: Aug 22, 2019

Researchers demonstrate how amorphous silicon TFTs can be used to drive flexible Micro-LED displays

Researchers from the University of Waterloo have demonstrated the successful integration of a-Si:H TFTs and high-efficiency micro-LED chips on large-area flexible substrates. This is the first time that an amorphous silicon was used to drive Micro-LEDs which could pave the way for lower-cost micro-LED display fabrication using existing LCD technology.

2T pixel circuit, before and after micro-LED transfer on a:SI (University of Waterloo, 2019)

the researchers use a 2-TFT pixel circuit, with blue GaN-based micro-LED chips. The low-temperature TFT production process enabled the direct integration onto a flexible flexible polyethylene naphthalate (PEN) substrate. After the TFT fabrication, the micro-LED chips were flip-chip bonded on the TFT, and then transferred onto the flexible pixel circuit using a selective laser lift-off process.

Read the full story Posted: Jul 19, 2019

CEA-Leti researchers developed a new CMOS-based process to produce high performance Micro-LED displays

Researchers at CEA-Leti developed a new process to produce high performance GaN Micro-LEDs displays, which the researchers say is simpler and more effective than current approaches.

CEA Leti RGB Micro-LED CMOS fabrication transfer method image

The first step in the new process is transferring the micro-LED chips directly on top of a CMOS wafer. In the second step each complete "pixel", made from a CMOS driving circuit and micro-LED chips, is transferred to the display substrate.

Read the full story Posted: May 14, 2019

Researchers develop a new technique to color-tune monolithic GaN LEDs

Researchers from Lehigh University, West Chester University, Osaka University and the University of Amsterdam developed a new technique to color-tune Gallium-Nitride (GaN) LEDs.

A tunable GaN:eu LED photo

The new technique is based on Atomic Emission Manipulation under Current Injection. The researchers demonstrated that it is possible to attain red, green and blue emissions originating from just one GaN LED-structure that uses doping with a single type of rare earth ion, Europium (Eu).

Read the full story Posted: Apr 28, 2019

NCTU researchers use ALD passivation layers to boost the efficiency of Micro-LEDs by over 140%

Researchers from the National Chiao Tung University (NCTU) in Taiwan has been able to enhance the light-emitting intensity of Micro-LEDs by 143.7% by using ALD passivation layers. The researchers used ALD equipment produced by Finland-based Picosun.

Picosun says that its Micro-LED technology has "immense potential" to dirupt the solid state lighting market, and its ALD solutions has been proven to dramatically boost the efficiency of Micro-LEDs.

Read the full story Posted: Apr 24, 2019

VerLASE Technologies announces new technologies for massively parallel assembly of microLED dies and films

VerLASE logoUS-based VerLASE Technologies announced that it is developing technologies for massively parallel assembly of microLED dies or films. The company has already files for multiple patents for its new technology.

VerLASE says that it is using practical methods and well-proven semiconductor and MEMs industry methods and existing tools. The company's technology will enable "deterministic, massively parallel transfers of microdie, with provisions that allow selective repair". The methods involve techniques used daily in Ink-Jet Printing but is not printing per se.

Read the full story Posted: Apr 21, 2019