Decoupling Polarization and Trap Charges by Direct V_mid Measurement for Insights into Dynamic Mechanisms of MFMIS-FeFET

In this work, the polarization switching <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\left(\mathrm{P}_{\text{FE}}\right)$</tex> and charge trapping (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{Q}_{\text{trap}}$</tex>) were decoupled by direct middle gate (MG) voltage (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\text{mid}}$</tex>) measurements on MFMIS-FeFET. The non-ideal effects of this method were thoroughly analyzed and optimized. According to the decoupled data, the channel side injection (Ct-Inj) and gate-side injection (Gt-Inj) were both observed, consistent with the previous reports. New phenomena regarding the frequency dependent <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{Q}_{\text{trap}}, \mathrm{P}_{\text{FE}}$</tex> speed and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\text{mid}}$</tex> amplitude were also revealed. We proposed that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{P}_{\text{FE}}$</tex> has a stronger gate voltage dependence than Ch-Inj, explaining all the findings. Based on these findings, guidelines for optimizing the writing frequency to enhance FeFET endurance were proposed.