Low-temperature plasma-engineered hafnia ferroelectrics for high-performance flexible thin-film transistors

Title : Low-temperature plasma-engineered hafnia ferroelectrics for high-performance flexible thin-film transistors

Abstract:

The demand for energy-efficient and flexible electronics has accelerated research into ferroelectric materials compatible with low-temperature processing. Hafnium-based ferroelectrics, particularly hafnium zirconium oxide (Hf_0.5Zr_0.5O₂, HZO), have attracted significant attention due to their CMOS compatibility, scalability, and robust polarization at nanometer thicknesses. However, conventional crystallization of HZO requires annealing temperatures above 400 °C, which limits its integration on temperature-sensitive substrates and two-dimensional (2D) materials.

In this work, we present a plasma-assisted approach that enables low-temperature stabilization of the ferroelectric orthorhombic phase in sputtered HZO thin films. Controlled argon plasma irradiation generates a moderate concentration of oxygen vacancies, which induce non-centrosymmetric lattice distortions and defect dipoles favorable for ferroelectricity. Structural and chemical analyses confirm that plasma treatment enhances the orthorhombic phase fraction without causing interfacial degradation. The resulting HZO films exhibit strong remanent polarization (>15 µC/cm²), low coercive field, and outstanding endurance exceeding 10⁷ switching cycles.

When integrated into indium-gallium-zinc-oxide (IGZO) thin-film transistors on flexible polyimide substrates, the plasma-engineered ferroelectric gate stack achieves a steep subthreshold swing below 60 mV/dec and a high ON/OFF ratio greater than 10⁶. These results demonstrate that plasma processing can effectively activate and tune ferroelectric behavior at a reduced thermal budget, thereby overcoming one of the major bottlenecks for flexible and monolithic 3D integrated electronics.

This study highlights the role of plasma irradiation both a crystallization enhancer and a defect-control tool for hafnia-based ferroelectrics. The demonstrated plasma-engineered ferroelectric transistors represent a viable route toward low-power, high-performance, and mechanically flexible device architectures, paving the way for next-generation intelligent systems and energy-efficient neuromorphic electronics.

Biography:

Hyunyeol Rho is a Ph.D. candidate in the Department of Advanced Materials Science and Engineering at Sungkyunkwan University, South Korea. His research focuses on hafnia-based ferroelectric thin films, plasma-assisted low-temperature processing, and flexible electronic devices. He has published a paper on plasma-engineered ferroelectrics and their integration into advanced transistor architectures. His current work aims to enable low-power, flexible and 3D integration with ferroelectric devices for next-generation electronics.