Ferroelectric HfZrOx Ge and GeSn PMOSFETs with Sub-60 mV/decade subthreshold swing, negligible hysteresis, and improved Ids

We report the first ferroelectric (FE) HfZrO
_x
(HZO) Ge and GeSn pMOSFETs with sub-60 mV/decade subthreshold swing (SS) (40~43 mV/decade), negligible hysteresis, and enhanced Ids. With a RTA at 450
^o
C, FE devices with reduced hysteresis of 40~60 mV demonstrate the significantly improved SS and I
_ds
characteristics compared to control devices without FE, owing to the negative capacitance (NC) effect induced by HZO. FE Ge and GeSn pFETs achieve 22% and 20% I
_ds
enhancement than control devices, respectively, at the drive voltage of 1.0 V. NC effect in FE devices is proved by the gate leakage and inversion capacitance characteristics.