Ferroelectric HfZrOx Ge and GeSn PMOSFETs with Sub-60 mV/decade subthreshold swing, negligible hysteresis, and improved Ids
We report the first ferroelectric (FE) HfZrOx (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 oC, FE devices with reduced hysteresis of 40∼60 mV demonstrate the significantly improved SS and Ids 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% Ids 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.