Engineering Hf0.5Zr0.5O2 Ferroelectric Tunnel Junctions With Amorphous WO x Bottom Electrodes Achieving High Remanent Polarization and Record Low-Operating Voltage

Metal–ferroelectric (FE)–metal structures with amorphous WOx bottom electrodes (BEs) are experimentally and theoretically demonstrated to favor the FE orthorhombic phase formation. The ferroelectric tunnel junction (FTJ) using the amorphous WOx BE and ZrO2-HfO2 superlattice FE layer has a remanent polarization of $70~\mu \text{C}$ /cm2. The FTJ has high endurance of 1E12 and 1E8 cycles for the write operation with incomplete and complete polarization switching, respectively. The write and read voltages have record low values of 1.3 and −0.15 V, respectively. The −0.15-V read does not cause read disturbance due to no polarization switching. The thermal budget is as low as 450 °C.