Experimental Study on the Role of Polarization Switching in Subthreshold Characteristics of HfO<inf>2</inf>-based Ferroelectric and Anti-ferroelectric FET

Abstract

We have experimentally studied and revealed the direct relationship between polarization switching and steep subthreshold slope (SS) characteristics of HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based ferroelectric FET (FeFET) and Anti-FeFET (A-FeFET) by systematically designing and fabricating devices, and monitoring Ig with high resolution, for the first time. In the circumstances that charge injection prevents polarization switching from occurring in subthreshold region of FeFET, we have obtained two major findings: (1) Sub-60 SS as low as 23.5 mV/dec is observed by adjusting V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> bias sequence, which is attributed to charge injection assisted by polarization switching. (2) Anti-ferroelectric facilitates to align polarization switching in subthreshold region and SS can be improved in A-FeFET as a consequence, which is directly observed by monitoring I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> .