Technical / research

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.

Researchers from the Hong Kong University of Science and Technology (Guangzhou), led by Prof. Yunda Wang, have developed a novel microLED transfer process, based on a dynamically programmable transfer head that uses localized heating to control a polymer's stickiness.

The researchers say that this new tool's ability to selectively handle a diverse range of geometries addresses a critical bottleneck in building complex microsystems. The researchers proved their system could selectively sort and transfer functioning 45-by-25-micrometer microLEDs to form custom layouts without degrading their performance.

Researchers at the CEA-Leti institute (a MicroLED Association member institute) developed green and red-emitting thin-film perovskite color conversion layers (CCLs) using pulsed laser deposition (PLD), that can be used in microLED microdisplays.

The researchers say that while QDs provide a good solution for color conversion microLED displays, they suffer from low absorption, which means that require a thickness of 3-10 micron, which is a challenge for very small microLEDs, required for microdisplays.

MicroLED-based optical interconnects are getting a lot of attention lately, as AI datacenters demands drive innovation and funds into the optical interconnect market.

According to TrendForce, microLED-based optical interconnect solutions are drastically more power efficient compared to copper-base solutions - in fact the overall microLED I/O system power consumption can be reduced to around 5% of the consumption of copper based systems.

Researchers from the University of Michigan, led by Prof. Zetian Mi, have developed a new 3D Nanowire red microLED emitter that achieves a very narrow emission spectrum - an FWHM of 5nm at 617 nm, about one order of magnitude narrower than previously reported values. A narrow emission spectrum helps to realize wide color gamuts.

To achieve this high performance, the researchers realized a nanowire photonic crystal (PhC) structure that reforms the radiation behavior of red-emitting InGaN micro-LEDs.

Researchers at the University of California, Santa Barbara, have designed a microLED with an increased beam spread and efficiency, that could replace traditional lasers in short-range data communication or display applications.

The researchers used distributed Bragg reflectors to laterally enclose the emitting region of the LED, and thus engineer the light emission. This new microLED architecture increased the emission output by 130% from the substrate side and 20% from the air-side, when compared to standard reference devices. The researchers also reported a 30% reduction in beam divergence.

Lam Research signed a multi-year research agreement with CEA-Leti, to advanced the fabrication of next-generation specialty semiconductor technologies. One of the focus areas is microLED displays.

CEA‑Leti said its role will center on rapid materials analysis and device characterization to support faster process optimization.

Researchers from Huazhong University of Science and Technology have reported a self-aligned laser transfer (SALT) based on directional photothermal regulation strategies that enables high-precision, programmable transfer of microchips or microLEDs without the need of precise laser-to-die alignment.

The researchers demonstrated multiple transfer printings of RGB MicroLED chips from different donor wafers highlight SALT’s self-aligned and batch-selective capabilities, which are crucial for efficient full-color MicroLED display assembly.