Short-channel robustness from negative capacitance in 2D NC-FETs

Applied Physics Letters, Volume 118, Issue 10, March 2021. To date, the robustness of performance, including tolerance to channel-length scaling effects, in scaled transistors has become increasingly important. Negative capacitance (NC) field-effect transistors (FETs) have drawn considerable attention and many studies have revealed that the NC effect is beneficial for device scaling. However, there is a lack of experimental evidence of short-channel behavior in NC-FETs with two-dimensional (2D) semiconducting channels and theoretical studies are limited. Here, we experimentally study 2D MoS2-based NC-FETs using MoS2 with CMOS-compatible hafnium zirconium oxide (HfZrO2 or HZO) as the ferroelectric (FE) and demonstrate remarkable short-channel behavior compared to similar 2D MoS2 FETs. It was observed that the subthreshold switching improvement becomes increasingly significant at shorter channel lengths, down to 20 nm. From analysis of the capacitive network, we show that the NC effect is impacted by a larger magnitude of polarization in the ferroelectric, which enhances gate control and is beneficial to channel-length scaling.