Direct Observation of Interface Charge Behaviors in FeFET by Quasi-Static Split C-V and Hall Techniques: Revealing FeFET Operation

Abstract

A quasi-static split C-V technique is proposed as a novel method to monitor ferroelectric polarization and charge distribution in FeFETs. In contrast to conventional split C-V, which is not applicable to FeFETs, the proposed technique successfully detects charges induced by V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> at the ferroelectric-semiconductor interfaces and extracts real P-V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> and Q-V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> characteristics of FeFETs. Through a combination with Hall measurements, responses of minority/majority carriers and trapped charges associated with polarization switching in FeFETs are experimentally obtained for the first time. It is found that trapped carriers, which screen ferroelectric polarization, is a key factor in the device operation of MFIS-FeFET. Our method, extracting Q-V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> loops directly from FeFET structures, is a powerful tool to understand the real operation and device physics of FeFETs including the memory window and the NC effect.