Development of Freestanding Ferroelectric Oxide Membranes with High-κ Dielectric Properties for Advanced Nanoelectronics

Jan-Chi Yang^1,2*

¹Department of Physics, National Cheng Kung University, Tainan, Taiwan
²Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan, Taiwan

* Presenter:Jan-Chi Yang, email:janchiyang@phys.ncku.edu.tw

The rapid evolution of two-dimensional semiconductor devices has driven intense research into novel dielectric materials that meet the growing demands for scalability, integration, and energy efficiency. Ferroelectric hafnium zirconium oxide (Hf₀.₅Zr₀.₅O₂, HZO) has emerged as a promising material due to its compatibility with silicon-based fabrications, high dielectric constant, and robust ferroelectric properties, even in ultrathin films. Our recent work addresses two critical challenges within this domain: the development of freestanding HZO (FS-HZO) membranes and the integration of high-κ FS-HZO as a top-gate dielectric for two-dimensional (2D) transistors. In this talk, I will talk about the investigation of FS-HZO membranes to uncover the interplay between the complex polymorphs and robust ferroelectricity. Our results reveal that thickness modulation affects phase composition and dielectric properties, where increased thickness diminishes the orthorhombic phase and ferroelectric response. To validate the practical role of FS-HZO membranes, we integrate FS-HZO as a high-κ dielectric in 2D semiconductor-based transistors, specifically with MoS₂. The HZO dielectrics demonstrate a high dielectric constant (~19.5), low leakage current, and stable ferroelectric properties, yielding MoS₂ transistors with an exceptional on/off ratio of 10⁹ and subthreshold swings as low as 53 mV dec⁻¹. Together, these studies advance the field of nanoelectronics by presenting viable solutions for incorporating high-quality freestanding membranes and 2D transistor technologies, highlighting the potential of freestanding membranes to propel future innovations in nanoelectronics.

Keywords: ferroelectric, oxide, thin film, freestanding membrane, high-κ dielectric