Interface Engineering on Ferroelectricity of Transparent Hf₀.₅Zr₀.₅O₂ Ferroelectric Capacitors

In this study, we explore the transparent hafnia-based ferroelectric capacitors (FeCaps), employing transparent indium tin oxide (ITO) as the electrode and quartz as substrate. Through interface engineering, involving a Ti interlayer between the ferroelectric Hf $_{{0}.{5}}$ Zr $_{{0}.{5}}$ O2 (HZO) film and the electrodes, we not only achieve a substantial enhancement in polarization, but also manage to process within a reduced thermal budget ( $350~^{\text {o}}$ C) compatible with back end of line (BEOL). The bottom interface is demonstrated to play the major role in improving the ferroelectric properties. Moreover, the transparent FeCaps exhibit a maximum transmittance of about 90% close to the bare substrate under visible light. These findings pave the way for hafnia-based FeCaps in the future advancement of transparent electronics.