Identification of Ferroelectricity in a Capacitor With Ultra-Thin (1.5-nm) Hf0.5Zr0.5O2 Film

The characterization of ferroelectricity in ultra-thin ferroelectric (FE) films is highly challenging due to enlarged leakage current and resistive switching (RS) effect. In this study, we investigated the polarization switching properties of 1.5-nm thick Hf0.5Zr0.5O2 (HZO) films via direct hysteresis remnant polarization/voltage (P–V) loop measurement. To reduce the leakage current and eliminate the RS effect, positive-up–negative-down (PUND) measurement was implemented on back-to-back connected complementary cells. Rational hysteresis loops, with remnant polarization of approximately $2~\mu \text{C}$ /cm2, were successfully obtained by directly measuring the polarization switching currents. In this study, we provide direct evidence of the stable ferroelectric property in 1.5-nm thick HZO films, and thereby show a potential prospect of ultimate scalability of HZO films.