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Breakthrough in Ultra-Thin Memory Devices! Taiwan’s First 2D Ferroelectric Material Unveils a New Era
2025/05/13
Next generation pioneers in 2D ferroelectric materials. This research was driven by a team of young scientists who achieved a major breakthrough (from letf: Dr.Sheng-Shawn Wong, Zhen-You Lin, Dr. Sheng-Zhu Ho)
With long-term support of the National Science and Technology Council and the Ministry of Education, a research team composed of members from the National Synchrotron Radiation Research Center (NSRRC), National Cheng Kung University (NCKU), and Tamkang University published a major breakthrough in Advanced Materials on April 16, 2025. The team successfully developed a reliable method for stacking-controlled van der Waals (vdW) heteroepitaxy, demonstrating for the first time the growth of an epitaxial ferroelectric hexagonal boron nitride (h-BN) ultra-thin film on graphene. This material exhibits homogeneous out-of-plane ferroelectricity that can be switched via interlayer sliding, signaling a promising advancement for next-generation high-efficiency, micro-scaled electronic devices and highlighting Taiwan’s leading role in the competitive field of 2D ferroelectric materials.

“Ferroelectricity” refers to a property in which a material exhibits spontaneous electric polarization that can be reversed by an external electric field—essentially functioning like an "electrical switch" to precisely control current flow. This characteristic makes ferroelectric materials ideal for use in memory devices, sensors, and low-power computing components. However, conventional ferroelectric materials are typically too thick, posing challenges for device miniaturization. h-BN, often referred to as “white graphene,” is a highly stable, ultra-thin 2D material with a symmetric hexagonal structure similar to graphene. Due to this symmetry, h-BN does not naturally exhibit ferroelectricity. Recent advances, however, have shown that such properties can be engineered in h-BN by manipulating its stacking arrangement or by integrating it with other 2D materials.

After years of dedicated research, a team led by Prof. Chung-Lin Wu (NCKU) achieved a breakthrough. Using plasma-assisted molecular beam epitaxy (PA-MBE), they first grew high-quality single-crystalline graphene on a silicon carbide (SiC) wafer, then precisely stacked h-BN layers atop it. This process resulted in an asymmetric stacking configuration of h-BN on the naturally formed Moiré-patterned graphene/SiC interface, inducing switchable out-of-plane polarization—a hallmark of ferroelectric behavior. Their technique not only overcomes a long-standing technological bottleneck but also enables wafer-scale precision control over thin-film growth with exceptional uniformity and stability.

Dr. Cheng-Maw Cheng, Head of the Scientific Research Division at NSRRC, emphasized that this achievement was made possible through close interdisciplinary collaboration across multiple universities. Using angle-resolved photoemission spectroscopy (ARPES) at the Taiwan Light Source (TLS), the team confirmed the evolution of band structure and interfacial polarization in the layer-controlled, multilayer h-BN/graphene heterostructure. Meanwhile, the theoretical simulations led by Prof. Hung-Chung Hsueh (Tamkang University) verified the electronic band properties of asymmetrically stacked multilayer h-BN. Subsequently, Prof. Yi-Chun Chen (NCKU) employedscanning probe microscopy (SPM) to confirm that the polarization states in these ultra-thin h-BN films are both stable and reversible—performance characteristics highly desirable for ferroelectric memory applications. The asymmetric stacking configuration and robust ferroelectric behavior of these h-BN films make them a promising platform for future volatile memory devices and AI hardware, particularly in high-speed, low-power matrix–vector operations. Moreover, their excellent structural compatibility with other 2D materials, such as graphene and molybdenum disulfide (MoS₂), enables the design of stacked heterostructure chips—paving the way for new breakthroughs in Taiwan’s semiconductor and optoelectronic industries.

Notably, the first author of this publication, Dr. Sheng-Shawn Wong, was awarded a Ph.D. scholarship sponsored by NSRRC. During his graduate studies, he demonstrated a strong commitment to advanced materials research and made full use of NSRRC’s multidisciplinary facilities to conduct his experiments. This publication represents one of his major research achievements and exemplifies the impact of interdisciplinary collaboration among scientists across different institutes. It also highlights the vital role of young physicists in Taiwan and their growing presence in the global scientific community.

https://doi.org/10.1002/adma.202414442