Ultralow Subthreshold Swing of a MOSFET Caused by Ferroelectric Polarization Reversal of Hf0.5Zr0.5O2 Thin Films

The emergence of complementary metal-oxide semiconductor (CMOS)-compatible HfO2-based ferroelectric materials provides a promising way to achieve ferroelectric field-effect transistors (FeFETs) with a steep subthreshold swing (SS) reduced to below the Boltzmann thermodynamics limit (& SIM;60 mV/dec at room temperature), which has important implications for lowering power consumption. In this work, a metal-oxide-semiconductor field-effect transistor (MOSFET) is connected with Hf0.5Zr0.5O2 (HZO)-based ferroelectric capacitors with different capacitances. By adjusting the capacitance of ferroelectric capacitors, an ultralow SS of & SIM;0.34 mV/dec in HfO2-based FeFETs can be achieved. More interestingly, by designing the sweeping voltage sequences, the SS can be adjusted to be 0 mV/dec with the drain current ranging over six orders of magnitude, and the threshold voltage for turning on the MOSFET can be further reduced. The manipulated SS could be attributed to the evolution of ferroelectric switching. Our work contributes to understanding the origin of ultralow SS in ferroelectric MOSFETs and the realization of low-power devices.

Automated summary

The emergence of CMOS-compatible HfO2-based ferroelectric materials enables the achievement of FeFETs with a steep subthreshold swing reduced to below the Boltzmann thermodynamics limit, which is crucial for reducing power consumption. This study demonstrates that by connecting a MOSFET with Hf0.5Zr0.5O2-based ferroelectric capacitors of different capacitances, an ultralow subthreshold swing of approximately 0.34 mV/dec can be achieved. Furthermore, by manipulating the sweeping voltage sequences, the subthreshold swing can be adjusted to 0 mV/dec with a wide range of drain current, and the threshold voltage for turning on the MOSFET can be further reduced. The manipulated subthreshold swing is attributed to the evolution of ferroelectric switching. This work contributes to understanding the origin of ultralow subthreshold swing in ferroelectric MOSFETs and the realization of low-power devices.