  The inferior electrical contact to two-dimensional (2D) materials is a
critical challenge for their application in post-silicon very large-scale
integrated circuits. Electrical contacts were generally related to their
resistive effect, quantified as contact resistance. With a systematic
investigation, this work demonstrates a capacitive
metal-insulator-semiconductor (MIS) field-effect at the electrical contacts to
2D materials: the field-effect depletes or accumulates charge carriers,
redistributes the voltage potential, and give rise to abnormal current
saturation and nonlinearity. On the one hand, the current saturation hinders
the devices' driving ability, which can be eliminated with carefully engineered
contact configurations. On the other hand, by introducing the nonlinearity to
monolithic analog artificial neural network circuits, the circuits' perception
ability can be significantly enhanced, as evidenced using a COVID-19 critical
illness prediction model. This work provides a comprehension of the
field-effect at the electrical contacts to 2D materials, which is fundamental
to the design, simulation, and fabrication of electronics based on 2D material.
