Researchers from Korea's Electronics and Telecommunications Research Institute (ETRI) developed a new process to produce microLED displays, which they say can be highly cost effective.
The new process is based on a novel film-like material developed at ETRI, called SITRAB. Using lasers, the process apparently detaches the microLED from the original epiwafer and bonds it to the SITRAB film in the same process step. The LEDs are then transferred to the final target backplane.
Researchers from King Abdullah's University of Science & Technology (KAUST) in Saudi Arabia developed GaN and InGan red microLED devices that are highly efficient.
The researchers managed to increase the efficiency of their previous design by a new chemical treatment that removes damages at the microLED sidewalls (created during the fabrication process) and also retains the high crystal quality at the InGaN and GaN sidewall interfaces.
Researchers from the University of Texas at Dallas developed a new method to create highly flexible microLED chips, that can be folded and twisted. The LEDs are detachable, and can be attached to almost an surface.
The researchers used remote epitaxy, to grow the LED crystals on a sapphire crystal substrate, coated with a one-atom layer of 2D graphene, which prevents the LED to stick to the sapphire substrate.
Kyocera and OSRAM have jointly designed a new hybrid current and PWM driving technology for microLED displays. The two companies says that this new driving scheme can be used to avoid using lower pixel currents through microLED chips, which reduces the deviation of the luminance and the color shift at lower grayscale levels.
Kyocera has presented a 3.9" full-color microLED display on an LTPS backplane that showed excellent performances that proves the validity of the new driving technology.
GE announced that it has been able to deposit its red phosphor (PFS-KSF) material using an inkjet printing process on a plastic substrate. This technology can be applied in future microLED and miniLED displays.
GE is also sampling a new green phosphor, that together with the red phosphor can attain 88% Rec. 2020. The company reveals that almost 40 billion LEDs with its PFS-KSF material were sold into commercial displays.
GaN-on-Si IP developer ALLOS Semiconductors announced it is collaborating with with Prof. Ohkawa and his team at King Abdullah University of Science and Technology (KAUST) to develop high efficiency nitride-based red LEDs on large diameter silicon substrates.
Prof. Ohkawa and team have developed an indium gallium nitride (InGaN)- based red LED stack with low forward voltage of less than 2.5 V and high efficiency by using local strain compensation and a modified MOCVD reactor design. ALLOS and the KAUST team will combine their unique technologies to handle strain and optimize crystal growth conditions for GaN-on-Si and red LEDs. To this end, the KAUST team will grow its red LED stack on top of ALLOS’ GaN-on-Si-buffer layers, which will be fine-tuned during the collaboration to optimize the performance of KAUST’s red LED stack.
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.
