Assessment of Steep-Subthreshold Swing Behaviors in Ferroelectric-Gate Field-Effect Transistors Caused by Positive Feedback of Polarization Reversal

Abstract

Steep-subthreshold swing ($SS$) behaviors in ferroelectric-gate field-effect transistors (Fe-FETs) are investigated using the metal-ferroelectric-metal-insulator-semiconductor (MFMIS) gates stack structures with different area ratios between MIS and MFM capacitors. It is analyzed that the capacitance matching between them by adjusting the area ratio is significant to efficiently utilize the polarization reversal behavior in the ferroelectric layer. In this work we explain the steep-SS behavior from viewpoint of positive feedback of polarization reversal. Furthermore it is discussed why steep-SS is observable in recent Fe-FETs.