Atomic layer bonding contacts in two-dimensional semiconductors.

Van der Waals contact between two-dimensional semiconductors and metals has always been inferior to covalent bond contacts used in semiconductor industry because of weak band coupling and low bond strength. Here, we report an atomic layer bonding (ALB) contact with strong band coupling and high interfacial cohesion by establishing a metallic coherent bonding interface between the transition-metal atomic layer of transition-metal dichalcogenides and metals. This contact exhibits ultralow contact resistance and superb thermomechanical stability, comparable to those of covalent bond contacts and surpassing all reported contact configurations. ALB contact formed in monolayer molybdenum disulfide and gold demonstrates a contact resistance of 70 ohm-micrometers and thermomechanical stability up to 400°C and delivers a maximum on-current of 1.1 milliamperes per micrometer after high-temperature annealing, all of which meet industrial integration. Editor's summary: Electrical contact between two-dimensional semiconductors and metals is usually weak because of weak band coupling and low bond strength. Gao et al. created a strong electrical contact between a gold electrode and molybdenum disulfide (MoS2) by using an ultrasoft argon plasma to etch away the topmost layer of sulfur to expose the molybdenum atoms. The researchers used this approach to fabricate MoS2 transistors that had contact resistances as low as 70 ohm·micrometer and were stable to temperatures as high as 400°C. —Phil Szuromi [ABSTRACT FROM AUTHOR]