Li Yi, Guo Yan, Li Jin, Xi Meiqi, Bai Lan, Zhang Jianfeng, Li Shu, Zhu Xuehao, He Yinghua, He Bingyu, Chen Xingxing, Zhang Yuting, Gong Yujia, Yin Zilun, Kang Jiahao, Peng Lian-Mao, Zhang Rong, Zhou Yugang, Cao Yu, Liang Xuelei
Key Laboratory for the Physics and Chemistry of Nanodevices, Center for Carbon-Based Electronics, School of Electronics, Peking University, Beijing 100871, China.
Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China.
ACS Nano. 2025 Jul 1;19(25):22837-22848. doi: 10.1021/acsnano.5c00672. Epub 2025 Jun 13.
Micro-light-emitting-diodes (μLEDs) are poised to revolutionize flat-panel display (FPD) technology with their exceptional brightness, contrast ratio, energy efficiency, and ultrahigh resolutions, making them indispensable for augmented reality (AR) and virtual reality (VR) microdisplays. However, the realization of high pixel-per-inch (PPI) μLED microdisplays demands advanced thin-film transistor (TFT) backplanes with robust driving capabilities. Presently, single-crystalline silicon CMOS dominates the industry for this application, but its nontransparent nature, wafer size limitations, and high fabrication cost restrict its scalability. Alternative technologies, including low-temperature polycrystalline silicon (LTPS) and metal oxide semiconductors, fail to deliver the required small device dimensions, driving performance, and stability. Two-dimensional transition metal dichalcogenides (TMDs) have shown potential, but their integration has faced challenges, such as complex transfer processes and limited scalability, resulting in only semiactive-matrix display demonstrations. Here, we present a prototype active-matrix (AM) μLED microdisplay driven by optimized carbon nanotube (CNT) TFTs with AlO/SiO gate dielectric stack and YO/SiO/polyimide passivation layers. Our CNT TFTs with a channel length () of 3 μm achieve a driving current of ∼10 μA/μm and a mobility of ∼27 cm/(V·s), while scaling to 0.5 μm enhances the driving current to ∼80 μA/μm and a mobility of ∼40 cm/(V·s), surpassing most previously reported CNT TFTs for AM displays and enabling AM-μLED microdisplays with a PPI up to 3400. Moreover, a heterogeneous integration process ultilizing flip-chip eutectic bonding was developed to assemble μLED arrays onto CNT TFT backplanes, achieving a yield of ∼100% aided by the PI layer. Furthermore, CNT TFT-based two-transistor, one-capacitor (2T1C) pixel-driving circuits and peripheral control circuits were designed to support both pulse amplitude modulation (PAM) and pulse width modulation (PWM) of μLED operation. These advancements culminate in a 32 × 32-pixel AM-μLED prototype microdisplay with a PPI of 357, capable of dynamic image and video display. Our work demonstrates CNT TFTs as a viable and scalable solution for next-generation μLED microdisplays.
微发光二极管（μLED）凭借其卓越的亮度、对比度、能源效率和超高分辨率，有望彻底改变平板显示（FPD）技术，使其成为增强现实（AR）和虚拟现实（VR）微显示器不可或缺的部件。然而，要实现高像素每英寸（PPI）的μLED微显示器，需要具备强大驱动能力的先进薄膜晶体管（TFT）背板。目前，单晶硅CMOS在该应用领域占据主导地位，但其不透明的特性、晶圆尺寸限制和高昂的制造成本限制了其可扩展性。包括低温多晶硅（LTPS）和金属氧化物半导体在内的替代技术，无法提供所需的小尺寸器件、驱动性能和稳定性。二维过渡金属二硫属化物（TMD）已展现出潜力，但其集成面临诸多挑战，如复杂的转移工艺和有限的可扩展性，仅实现了半有源矩阵显示演示。在此，我们展示了一种由优化的碳纳米管（CNT）TFT驱动的有源矩阵（AM）μLED微显示器原型，该TFT具有AlO/SiO栅极介电堆栈和YO/SiO/聚酰亚胺钝化层。我们的沟道长度（）为3μm的CNT TFT实现了约10μA/μm的驱动电流和约27cm²/(V·s)的迁移率，而缩小至0.5μm时，驱动电流提高到约80μA/μm，迁移率达到约40cm²/(V·s)，超过了此前报道的大多数用于AM显示器的CNT TFT，并实现了PPI高达3400的AM-μLED微显示器。此外，还开发了一种利用倒装芯片共晶键合的异质集成工艺，将μLED阵列组装到CNT TFT背板上，在PI层的辅助下实现了约100%的良品率。此外，基于CNT TFT的双晶体管单电容（2T1C）像素驱动电路和外围控制电路被设计用于支持μLED操作的脉冲幅度调制（PAM）和脉冲宽度调制（PWM）。这些进展最终促成了一款32×32像素、PPI为357的AM-μLED原型微显示器，能够进行动态图像和视频显示。我们的工作证明了CNT TFT是下一代μLED微显示器可行且可扩展的解决方案。
