Technical / research

Researchers from the Beijing Institute of Technology developed a spatially shaped femtosecond-laser method for fabricating ultrafine quantum-dot pixels, that can be placed on top of microLEDs, for color-conversion display production. The method combines high-precision laser drilling with selective quantum-dot filling.

The process that the researchers developed starts with a glass substrate coated with a thin SU-8 polymer layer. A femtosecond laser was then used to drill ordered micro-hole arrays into the polymer. It is reported that the spatially shaped Bessel beam produced holes with clear entrances, smooth sidewalls, and low taper, with limited damage to the underlying glass. The holes can be as small as 100 nm.

Back in 2024, we reported that researchers from Korea's KAIST developed an flexible phototherapy microLED face mask, with the goal of slowing down skin aging.

The researchers, in collaboration with AMOREPACIFIC, now report that they have designed an improved mask, and have demonstrated the benefits. 

Researchers from Korea University, with colleagues from Shivaji University and Gyeongsang National University, have developed a transparent resistive memory device designed to drive individual microLED pixels, offering an alternative to the thin-film-transistor-and-capacitor circuits used in conventional active-matrix backplanes.

This research targets a persistent problem in transparent microLED displays, where the driving element must combine low off-state current, stable multilevel switching, and high optical transmittance. The researchers say that oxide-based transparent memories tend to exchange oxygen with the indium tin oxide (ITO) electrodes, producing high leakage and unstable switching, while nitride-based devices are more stable at the interface but usually switch abruptly between two states because of deep nitrogen-vacancy traps, making reliable grayscale operation difficult.

Researchers from China's Fudan University, in collaboration with researchers from Peking University, have developed high-performance microLED arrays, on diamond substrates, suitable for optical I/O.

The research combines several enabling technologies, including long-wavelength InGaN epitaxy, three-quantum-well active region design, diamond heterogeneous integration, transfer printing and two-photon fabricated microlenses. This resulted in highly efficient microLEDs, with very low drive currents and excellent energy efficiency. The researchers say that the diamond substrates effectively suppress self-heating, enabling high-speed operation while significantly improving thermal management compared with conventional glass substrates.

Shenzhen-based MTC announced that together with the Future Technology Institute at Hunan Normal University, it is establishing a laboratory for microLED Co-Packaged Optics (CPO, or Optical I/O).

MTC says that the new lab will focus enhancing the communication performance of microLED devices and arrays, testing and validation, and prototype system design. This is applied research - MTC hopes to be ale to release sample products based on the lab research in 2027, with pilot production starting in 2028.

Researchers at UCSB developed a scalable monolithic transfer process that uses selective electrochemical etching of a highly doped GaN sacrificial layer combined with wafer bonding to release and transfer fully fabricated micro-LED arrays onto silicon in a single step.

The researchers report that this breakthrough process eliminates laser lift-off and serial pick-and-place transfer, enabling low-damage, high-throughput heterogeneous integration of microLEDs devices for displays, optical interconnects, and sensing.

US-based Ingantec announced an exclusive licensing agreement with the Wisconsin Alumni Research Foundation (WARF), for its patents in advanced strain engineering and the utilization of pseudo-substrates—technologies.

Ingantec says that the licensed IP, developed by University of Wisconsin-Madison Professors Shubhra Pasayat and Chirag Gupta, utilizes porosification and electrochemical etching techniques to create strain-relaxed Indium Gallium Nitride (InGaN) templates. Inagntec says that these methods may hold promises for solving the “green gap” problem —the precipitous drop in efficiency as InGaN based microLEDs move from blue to green and red.  

Researchers at the The University of Osaka, in collaboration with Ritsumeikan University have shown how growing europium-doped gallium nitride (Eu-doped GaN) on a semipolar crystal plane dramatically improves red light emission. 

The researchers say that EU-doped GaN is a promising next-generation microLED material platform, as it provides narrow-linewidth, wavelength-stable red emission based on intra-4f-shell transitions of Eu ions. In this research, it was found that growing these on a semipolar crystal plane selectively promotes the formation of highly efficient Eu luminescent centers, resulting in red emission intensity more than 3.6 times higher than that of a conventionally grown material.

Scientists at the University of Hong Kong (HKU), led by Prof. Yang Lu, have successfully used mechanical stretching technology to dynamically control the emission color of GaN LEDs, from UV to blue light.

The researchers utilized micro-nano processing technology to fabricate single-crystalline GaN material into tiny bridge-like structures. Through precise mechanical stretching, the material achieved an elastic deformation of up to 6.8%, with a tensile strength of approximately 11 GPa. This demonstrates the extraordinary elastic deformation capability brought by the size effect, offering broad prospects for deep strain engineering.

Researchers from the University of Waterloo have demonstrated how a combined dry/wet etching process with polymeric encapsulation to construct InGaN-based microLEDs that show negligible degradation due to sidewall effects for devices having diameters as small as 6 µm.

The researchers report that the microLEDs exhibit low surface recombination velocities ( <10 cm s⁻¹) and high wall plug efficiencies of 20.3% at a current density of 2.5A cm^-2.