Research Excellence

With the advances in technology, electronic devices are getting smaller and more functional. Exploring ultrathin and high-performance nanomaterials for electronic devices has become the biggest challenge. Ferroelectrics are a special class of piezoelectric materials that exhibit spontaneous electrical polarizations switchable by an external electric field. As a class of multifunctional materials, they are the basis of new designs for transistors, memory, and neuromorphic devices. However, conventional ferroelectric materials lose their efficiency at the nanometre scale.

Prof. Daniel Lau, Head of the Department of Applied Physics, and his research team have achieved a significant breakthrough in 2D ferroelectric materials. The development has been published in one of the most prestigious journals, Science. The team has shown how the widely known nanomaterials molybdenum disulfide (MoS2) and tungsten disulfide (WS2), although not ferroelectric by themselves, can be stacked to form a new heterogeneous crystal that is ferroelectric in nature. It happens through the interaction of the atoms of both materials with each other. The team also developed a simple one-step process to generate the new ferroelectric layers. The final product is only two molecular layers thin, at the very limit of what nano-sized means. This discovery is an important step to making ultra-thin electronics at a low cost and high reproducibility rate, creating new 2D ferroelectric materials.
Learn more: https://www.science.org/doi/10.1126/science.abm5734

二維鐵電材料領域重要突破

隨著科技發展，電子產品越趨輕巧和多功能。發展超薄及高性能的納米材料成為電子產品研發的一個重大挑戰。鐵電體是一類特殊的壓電材料，它具有自發極化，可以通過外加電場進行切換的特性。因此，鐵電材料被廣泛應用於電晶體、記憶體和神經形態設備等不同領域。可惜傳統的鐵電材料在到達納米大小時便喪失效能。

應用物理學系系主任劉樹平教授及其研究團隊，在鐵電材料研究領域上取得了重大的突破，這項研究更刊載於世界頂級科技期刊《Science》。劉教授發現納米材料二硫化鉬 (MoS2) 和二硫化鎢 (WS2)，雖然兩者本身不是鐵電體，但可以堆疊形成一種新的、具備鐵電性的異質晶體。這種新的鐵電薄膜是通過兩種材料的原子之間的相互作用形成。研究團隊還開發了簡便方法來製備新的鐵電薄膜。最終的成品只有兩個分子層，處於納米尺寸的極限。 這項發現是以低成本和易複製的方法來製備超薄電子產品的重要一步，更開拓了二維鐵電材料家族的新成員。
了解更多：https://www.science.org/doi/10.1126/science.abm5734