  Ferroelectric field-effect transistors (FeFET) with two-dimensional (2D)
semiconductor channels are promising low-power, embedded non-volatile 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 fivefold
increase in on-state current (~120 uA/um at 1 V) and on-to-off ratio (~2*10^7)
in the FeFETs. In addition, the high carrier concentration in the MoS2 channel
during the on-state (> 10^14 cm^-2) facilitates the observation of a
metal-to-insulator phase transition in monolayer MoS2 permitting observation of
high field effect mobility (> 100 cm^2V^-1s^-1) at cryogenic temperatures. Our
work and devices broaden the potential of FeFETs and provides a unique platform
to implement high-carrier-density transport in a 2D channel.
