en.Wedoany.com Reported - Recently, Professor Liu Chao's team from the School of Integrated Circuits at Shandong University made significant progress in the field of Micro-LED display technology, achieving a monolithically integrated all-gallium nitride (GaN) actively-driven Micro-LED display module. The related results were published under the title "All-GaN monolithic integration of 2T1C pixel circuits with μLEDs" in Optics Letters, a prestigious journal in the field of optics. Doctoral student Gao Yipin from the School of Integrated Circuits at Shandong University is the first author of the paper, and Professor Liu Chao is the corresponding author.

With advantages such as high brightness, high contrast, long lifespan, and low energy consumption, Micro-LEDs are considered one of the strong contenders for next-generation high-end display technology. However, there are fundamental material and process incompatibilities between the current mainstream silicon-based CMOS or thin-film transistor (TFT) pixel driving schemes and GaN-based Micro-LEDs, typically requiring the introduction of complex mass transfer and metal bonding processes. This hybrid integration route not only easily leads to key technology challenges such as thermal mismatch, parasitic effects, and alignment errors, but also significantly increases manufacturing costs, restricting the large-scale fabrication and industrialization of large-area, high-density Micro-LED display arrays. Therefore, achieving monolithic integration of pixel circuits and Micro-LEDs on a single GaN material platform has become a key research direction for breaking through the technical bottlenecks of existing integration routes and building high-performance, low-cost Micro-LED display chips.

To address this industry challenge, Professor Liu Chao's team developed a self-aligned selective-area epitaxial regrowth technique. Based on a 4-inch GaN-based high electron mobility transistor (HEMT) epitaxial structure, the research team successfully achieved wafer-level precise regrowth and seamless electrical interconnection of Micro-LEDs. The epitaxially regrown Micro-LED structures demonstrated excellent thickness uniformity and compositional homogeneity. The developed monolithically integrated all-GaN-based 2T1C-μLED display module can achieve effective brightness control and reliable, stable switching capabilities, demonstrating the immense potential of the all-GaN monolithic integration architecture in fine grayscale control and high refresh rates.

The all-GaN monolithic integration scheme fundamentally avoids the complex transfer and bonding processes of traditional hybrid integration routes. While simplifying integration complexity and reducing costs, it is expected to fully leverage the intrinsic advantages of the GaN material system in high frequency, high efficiency, and high reliability. The realization of the monolithically integrated 2T1C-μLED display module marks a progression of all-GaN monolithic integration technology from simple device-level switching dimming to a practical circuit-level pixel driving architecture, providing key technical support and a feasible development path for the fabrication of next-generation high-performance active-matrix Micro-LED display chips.

This research was supported by the National Key Research and Development Program of China for Young Scientists.

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