Understanding the Slow Erase Operation in IGZO-Channel FeFETs: The Role of Positive Charge Generation Kinetics

Abstract

This work systematically investigates the programming and erasing dynamics of IGZO-channel back-gated FeFETs, uncovering that erase operation is significantly slower than programming. PUND measurements in ferroelectric capacitors with IGZO top electrodes reveal that the ferroelectric switching kinetics under negative bias are limited by the generation of positive charges. Two underlying physical mechanisms are identified: (1) IGZO-bandgap donor states, which can get positively charged by emitting electrons to Conduction Band and reversibly neutralized during programming, help ferroelectric switching and limits the switching kinetics; and (2) hydrogen doping into IGZO, which proceeds at a much slower rate and is irreversible, thus incapable of supporting ferroelectric switching. This work emphasizes the importance to deepen the understanding of erasing kinetics to enable low-latency, and high-endurance applications of oxide-semiconductor-channel FeFETs.