Effects of Thickness and Anisotropic Strain on Polarization Switching Properties of Sub-10 Nm Epitaxial Hf0.5Zr0.5O2 Thin Films

Abstract Doped HfO2-based ferroelectric (FE) films are emerging as leading contenders for the next generation of FE non-volatile memory due to their excellent compatibility with complementary metal oxide semiconductor processes and robust ferroelectricity at nanoscale dimensions. Despite the considerable attention given to the FE properties of HfO2-based films in recent years, enhancing their polarization switching speed remains a critical research challenge. In this study, we demonstrate the strong ferroelectricity of sub-10 nm Hf0.5Zr0.5O2 (HZO) thin films and show that the polarization switching speed of these thin films can be significantly affected by HZO thickness and anisotropically-strained LSMO-buffered layer. Our observations indicate that the the HZO thin film thickness and anisotropically-strained LSMO layer influence the nucleation of reverse domains by altering the phase composition of the HZO thin film, thereby reducing the polarization switching time. Although the increase in HZO thickness and anisotropic compressive strain hinder the formation of the FE phase, they can enable faster switching. Our findings suggest that FE HZO ultrathin films with polar orthorhombic structures have broad application prospects in microelectronic devices. These insights into novel methods for increasing polarization switching speed are poised to advance the development of high-performance FE devices.