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

Abstract

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.