One-Dimensional Edge Contacts to Two-Dimensional Transition-Metal Dichalcogenides: Uncovering the Role of Schottky-Barrier Anisotropy in Charge Transport across MoS2 /Metal Interfaces

Abstract

Low-resistance ohmic contacts are a prerequisite for implementing two-dimensional transition-metal dichalcogenides (2D TMDs) in a host of applications. Edge contacts offer unique advantages, yet their electrical properties are not fully understood. Employing an $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ framework, the authors find that edge contacts to monolayer MoS${}_{2}$ are pinned to a charge-neutrality level close to the valence band and are $p$-type---unlike typical $n$-type top contacts. This anisotropy in Fermi-level pinning complicates conduction through metal-TMD interfaces and affects design guidelines for low-resistance contacts. Challenges, potential mitigating solutions, and opportunities that leverage this anisotropy are discussed.