First Direct Experimental Studies of Hf 0.5 Zr 0.5 O 2 Ferroelectric Polarization Switching Down to 100-picosecond in Sub-60mV/dec Germanium Ferroelectric Nanowire FETs

In this work, ultrafast pulses with pulse widths ranging from 100 ps to seconds were applied on the gate of Ge ferroelectric (FE) nanowire (NW) pFETs with FE Hf 0.5 Zr 0.5 O 2 (HZO) gate dielectric exhibiting steep subthreshold slope (SS) below 60 mV/dec bi-directionally. With applied gate bias pulses (V G = -1 to -10 V), high-mobility Ge drain current was monitored as a test vehicle to capture the polarization switching of HZO. It was found that HZO could switch its polarization directly by a single pulse with the minimum pulse width of 3.6 ns. The polarization switching triggered by pulse train with pulse width as short as 100 ps was demonstrated for the first time.