Deep UV microLED for maskless lithography; avalanching nanoparticles for optical computing; Probabilistic computing with stochastic spintronics.
Researchers from the Hong Kong University of Science and Technology, Southern University of Science and Technology, and the Suzhou Institute of Nanotechnology developed an aluminum gallium nitride deep-ultraviolet microLED display array for maskless lithography. They also built a maskless lithography prototype platform.
“The team achieved key breakthroughs for the first microLED device including high power, high light efficiency, high-resolution pattern display, improved screen performance and fast exposure ability. This deep-UV microLED display chip integrates the ultraviolet light source with the pattern on the mask. It provides sufficient irradiation dose for photoresist exposure in a short time, creating a new path for semiconductor manufacturing,” said Hoi-Sing Kwok, a professor and founding director of the State Key Laboratory of Advanced Displays and Optoelectronics Technologies at HKUST, in a statement.
In future work, the team plans to enhance the performance of the AlGaN deep ultraviolet microLEDs, improve the prototype, and develop 2k to 8k high-resolution deep ultraviolet microLED display screens. [1]
Researchers from Oregon State University, Lawrence Berkeley National Laboratory, Columbia University, and the Autonomous University of Madrid discovered luminescent nanocrystals that can be quickly toggled from light to dark and back again with potential to be used in optical computing and memory.
The nanocrystals are composed of potassium, chlorine and lead and doped with neodymium. While the potassium lead chloride nanocrystals do not interact with light, they enable the neodymium ions to handle light signals more efficiently.
“Normally, luminescent materials give off light when they are excited by a laser and remain dark when they are not. In contrast, we were surprised to find that our nanocrystals live parallel lives. Under certain conditions, they show a peculiar behavior: They can be either bright or dark under exactly the same laser excitation wavelength and power,” said Artiom Skripka, assistant professor in the OSU College of Science, in a press release. “If the crystals are dark to start with, we need a higher laser power to switch them on and observe emission, but once they emit, they remain emitting and we can observe their emission at lower laser powers than we needed to switch them on initially.”
Optically bistable nanocrystals can store information that is written and read entirely through light, making them useful for building small and scalable optical memory units. These nanocrystals are controlled by lasers: one delivers continuous power, while the other triggers them to emit light after a brief pulse. This functionality mimics the behavior of electronic transistors and paves the way for devices where light controls light. (Credit: Artiom Skripka, OSU College of Science)
Integrating photonic materials with this intrinsic optical bistability could lead to optical computers with faster and more efficient data processing, noted Skripka, but said that more work is needed. “Our findings are an exciting development, but more research is necessary to address challenges such as scalability and integration with existing technologies before our discovery finds a home in practical applications.” [2]
Researchers at Tohoku University and the University of California Santa Barbara developed new computing hardware for generative AI that utilizes a Gaussian probabilistic bit (g-bit) made from stochastic magnetic tunnel junctions.
The g-bits have the ability to generate Gaussian random numbers, complementing probabilistic bits that work with binary variables by enabling optimization and machine learning with continuous variables. The researchers said that this benefits diffusion models by handling iterative stages more efficiently, reducing energy consumption and speeding up the generation of high-quality outputs. Other potential applications include portfolio optimization and mixed-variable problems. [3]
[1] Feng, F., Liu, Y., Zhang, K. et al. High-power AlGaN deep-ultraviolet micro-light-emitting diode displays for maskless photolithography. Nat. Photon. (2024). https://doi.org/10.1038/s41566-024-01551-7
[2] Skripka, A., Zhang, Z., Qi, X. et al. Intrinsic optical bistability of photon avalanching nanocrystals. Nat. Photon. (2025). https://doi.org/10.1038/s41566-024-01577-x
[3] Singh, N. S., Delacour, C., Niazi, S. et al. Beyond Ising: Mixed Continuous Optimization with Gaussian Probabilistic Bits using Stochastic MTJs. 70th Annual IEEE International Electron Devices Meeting https://iedm24.mapyourshow.com/8_0/sessions/session-details.cfm?ScheduleID=418
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