Ferroelectric Negative Capacitance GeSn PFETs With Sub-20 mV/decade Subthreshold Swing
Negative capacitance (NC) GeSn pFETs integrated with HfZrO<sub><italic>x</italic></sub> (HZO) ferroelectric film is demonstrated with sub-20 mV/decade subthreshold swing (SS) over two orders of magnitude of <inline-formula> <tex-math notation="LaTeX">${I}_{\text {DS}}$ </tex-math></inline-formula>. The ratio of remnant polarization to coercivity in HZO is significantly improved with the increasing of the annealing temperature from 400 °C to 500 °C, which contributes to the effective reduction of hysteresis in ferroelectric NC GeSn transistors. Ferroelectric NC GeSn pFET annealed at 500 °C achieves a hysteresis of 70 mV while maintaining a steep SS dramatically lower than 60 mV/decade, and an improved <inline-formula> <tex-math notation="LaTeX">${I}_{\text {DS}}$ </tex-math></inline-formula> over control device without HZO.