Field-effect at electrical contacts to two-dimensional materials

TL;DR

This paper uncovers a capacitive field-effect at electrical contacts to 2D materials, revealing how it influences device behavior and can be harnessed to improve neural network circuits for medical predictions.

Contribution

It introduces the concept of a capacitive field-effect at 2D material contacts and demonstrates its impact on device performance and neural network applications.

Findings

Field-effect causes charge redistribution and current nonlinearity.

Engineered contacts can eliminate current saturation.

Nonlinearity enhances neural network perception capabilities.

Abstract

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.