Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe2, MoS2, and MoSe2 Transistors

TL;DR

This paper introduces a universal 2D/2D contact strategy for TMD transistors, achieving low resistance, high on/off ratios, and high mobility, significantly enhancing 2D material device performance.

Contribution

A novel van der Waals assembly method for low-resistance 2D/2D ohmic contacts across various TMDs, improving transistor performance.

Findings

Achieved contact resistance of ~0.3 kΩ·μm in WSe2 FETs.

Demonstrated high on/off ratios exceeding 10^9.

Observed high drive currents over 320 μA/μm.

Abstract

We report a new strategy for fabricating 2D/2D low-resistance ohmic contacts for a variety of transition metal dichalcogenides (TMDs) using van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. We demonstrate that few-layer WSe2 field-effect transistors (FETs) with 2D/2D contacts exhibit low contact resistances of ~ 0.3 k ohm.um, high on/off ratios up to > 109, and high drive currents exceeding 320 uA um-1. These favorable characteristics are combined with a two-terminal field-effect hole mobility ~ 2x102 cm2 V-1 s-1 at room temperature, which increases to >2x103 cm2 V-1 s-1 at cryogenic temperatures. We observe a similar performance also in MoS2 and MoSe2 FETs with 2D/2D drain and source contacts. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and a wide variety of other 2D materials as the channel materials in post-silicon electronics.