The device concept of operating ferroelectric field effect transistors (FETs)
in the negative capacitance (NC) regime offers a promising route for achieving
energy-efficient logic applications that can outperform the conventional CMOS
technology, while the viable mechanisms for stabilizing the NC mode remain a
central topic of debate. In this work, we report hysteresis-free steep slope
switching in few-layer and bilayer MoS2 transistors back-gated by single
layer polycrystalline PbZr0.35Ti0.65O3 films. The devices exhibit
current on/off ratios up to 8×106 within an ultra-low gate voltage
window of Vg = ±0.5 V and subthreshold swing as low as 9.7 mV/decade at
room temperature, transcending the 60 mV/decade Boltzmann limit. Unlike
previous studies, the quasi-static NC mode is realized in a ferroelectric
without involving an additional dielectric layer. Theoretical modeling reveals
the dominant role of the metastable polar states within ferroelectric domain
walls in enabling the NC mode in the MoS2 transistors. Our findings shed
light into a new mechanism for NC operation, providing a simple yet effective
material strategy for developing high speed, low-power 2D nanoelectronics.Comment: 15 pages, 5 figure