Threshold Selector and Capacitive Coupled Assist Techniques for Write Voltage Reduction in Metal–Ferroelectric–Metal Field-Effect Transistor

We propose device and circuit assist techniques to lower the ferroelectric–metal field-effect transistor (FeMFET) write voltage while lowering the effect of depolarizing field. A bipolar threshold selector (TS) is connected between the intermediate node of a FeMFET and
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, which provides a low-impedance bypass path by triggering an insulator to metallic transition during a write operation. This lowers the voltage drop across MOSFET and reduces the write voltage to ~1.7 V. For further reduction in write voltage, the MOSFET in the FeMFET is utilized as a circuit assist by repurposing it as a capacitive coupling device. It reduces the write voltage to ~1.4 V. During the read mode, TS is in insulating state and does not alter the capacitive voltage divider action. Read is followed by a data-dependent write-back stage to bring the polarization close to retention polarization. During the retention mode, TS acts as a weak bleeder resistor, reducing noise coupling and depolarizing field. TS parameter sensitivity for write voltage reduction along with row hammer effect of the proposed read- and write-back operation is also presented.