Time-Resolved Measurement of Negative Capacitance

Abstract

To reduce the power consumption in scaled CMOS integrated circuits, transistors operating at low supply voltage with steep subthreshold swing (SS) are highly desirable. The negative capacitance (NC) effect in ferroelectric materials has emerged as a possible solution for achieving steep SS in transistors. In order to effectively leverage this effect in device applications, a proper understanding of its time-dependent nature is crucial. Here, we demonstrate that the NC effect occurs within a time window which is bounded by the switching time of ferroelectric domains at the faster time limit and screening charge compensation time of polarization at the slower time limit. We study this temporal dynamics of NC effect both by performing the transient measurements of metal-ferroelectric hafnium zirconium oxide-insulator-semiconductor capacitor connected in series with a load resistor and by characterizing NC field-effect transistors (NCFETs) at different time scales. Our experimental results provide deeper insight into the understanding of NC effect, reveal the time dependent switching nature of NCFETs, and pave way for the advancement of steep-slope transistors technology.