Discrete Ferroelectric Polarization Switching in Nanoscale Oxide-Channel Ferroelectric Field-Effect Transistors

In this work, we study polarization switching behavior in scaled hafnium-zirconium oxide (HZO) ferroelectric (FE) field-effect transistors with an amorphous oxide-semiconductor channel with dimensions down to the FE domain level. Channel thickness scaling acts as an effective approach to memory window (MW) enhancement. With an indium-tin oxide channel thickness of 2.5 nm, we demonstrate a large MW of 2.2 V. Discrete FE polarization switching is observed in narrow- and short-channel transistors, where a small number of FE domains are involved. Based on a detailed MW scaling study with channel length, we estimate the size of the FE domain in our HZO to be ∼40 nm. Fatigue experiments in nanoscale transistors reveal the dominant role of FE domain pinning, which leads to negative threshold voltage shift and degraded MW. Our results open up a new avenue for probing FE physics based on single domain behavior.