Technical / research - Page 8

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.

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.

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.

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.

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.

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.

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.

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).

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.

US-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.

The Germany Bavarian state ministry for regional development has funded a new three-year project to develop transparent micro-LED displays for automotive applications.

The SmartVIZ project consortium consists of Osram, Fraunhofer IISB and ASM Amicra. The partners aim to develop direct-view high-resolution transparent and demonstrate a prototype in October 2021.

Researchers from the US National Institute of Standards and Technology (NIST) developed new GaN nanowire-based ultraviolet LEDs that are five times as bright as regular LEDs. The new design uses a silicon-doped GaN nanowire core coated with a shell made from magnesium-doped GaN and Aluminum.

The nanowires are built in a p-i-n structure and the researcher say that adding the Aluminum to the shell of the LED helps confine electrons to the nanowire core by introducing an asymmetry in the electrical current which boost the electroluminescence of the device.

Researchers from the Rochester Institute of Technology managed to vertically integrate nanowire gallium nitride (GaN) field-effect transistors (FETs) and indium gallium nitride (InGaN) LEDs. Such technology could be useful for future Micro-LED displays.

The researchers say that this integration could provide to enable smaller structures and more cost-effective processes compared to alternative light emitting architectures - such as high-electron-mobility transistor (HEMT) combined with LEDs.

HDTVTest posted an interesting interview with Cadmium-Free QD developer Nanosys CEO and president Jason Hartlove. In this long interview Jason discusses the company's technology and recent achievements.

Jason explains that producing an RGB Micro-LED has many challenges as each color micro-LED chip is different - and different color LEDs need slightly different voltages and drive currents. The mechanical placement of these chips is also much more difficult for three colors. Using single-color (blue) Micro-LED chips and color-converting them using QDs makes a lot of sense for such displays - with easier manufacturing, longer lifetime, less differential aging (burn-in) and a wider color gamut.