High Current and Carrier Densities in 2D MoS2/AlScN Field-Effect Transistors via Ferroelectric Gating and Ohmic Contacts

Abstract

Ferroelectric field-effect transistors (FeFET) with two-dimensional (2D) semiconductor channels are promising low-power, embedded nonvolatile memory (NVM) candidates for next-generation in-memory computing. However, the performance of FeFETs can be limited by a charge imbalance between the ferroelectric layer and the channel and, for low-dimensional semiconductors, also by a high contact resistance between the metal electrodes and the channel. Here, we report a significant enhancement in performance of contact-engineered FeFETs with a 2D MoS2 channel and a ferroelectric Al0.68Sc0.32N (AlScN) gate dielectric. Replacing Ti with In contact electrodes results in a 5-fold increase in on-state current (similar to 120 mu A/mu m at 1 V) and on-to-off ratio (similar to 2 x 10(7)) in the FeFETs. In addition, the high carrier concentration in the MoS2 channel during the on-state (>10(14) cm(-2)) owing to the large remnant polarization of AlScN facilitates the observation of a metal-to-insulator electronic phase transition in monolayer MoS2 permitting observation of high field-effect mobility (>100 cm(2) V-1 s(-1)) at cryogenic temperatures. Our work and devices broaden the potential of FeFETs and provide a platform to implement high-carrier-density transport in a 2D channel.