A preliminary study on mist CVD-derived ferroelectric Hf1−x Zr x O2 films featuring its possibility of suitable operation for non-volatile analog memory

We have newly developed mist CVD-derived Hf1−x Zr x O2 films and investigated their physical properties and basic electrical properties for application to ferroelectric analog memory device such as synaptic device for neuromorphic system. It is observed that the films consisted of microcrystal grain including ferroelectric orthorhombic phase by AFM and GIXRD measurements. Both HfO2 and ZrO2 film with 20 nm thickness showed good fatigue endurance against 109 counts of imposed pulse cycling, where some wakeup phenomena were observed. For a range of electric field (up to 1.5 MV cm−1) as memory-writing input with condition of minor ferroelectric hysteresis loop, a linear relationship between the input and resultant polarization at zero electric field, P(E = 0), was obtained. Finally, it is suggested that those films of HfO2, Hf0.55Zr0.45O2 and ZrO2 are basically applicable for the ferroelectric analog memory device. Further investigation is needed in view of degradation against the input electric field and imposed fatigue pulse.