Electron transport through metal/MoS2 interfaces: edge- or area-dependent process?

Abstract

In ultra-thin two-dimensional (2-D) materials, the formation of ohmic contacts with top metallic layers is a challenging task that involves different processes than in bulk-like structures. Besides the Schottky barrier height, the transfer length of electrons between metals and 2-D monolayers is a highly relevant parameter. For MoS${}_2$, both short ($\le$30 nm) and long ($\ge$0.5 $\mu$m) values have been reported, corresponding to either an abrupt carrier injection at the contact edge or a more gradual transfer of electrons over a large contact area. Here we use \textit{ab initio} quantum transport simulations to demonstrate that the presence of an oxide layer between a metallic contact and a MoS${}_2$ monolayer, for example TiO${}_2$ in case of titanium electrodes, favors an area-dependent process with a long transfer length, while a perfectly clean metal-semiconductor interface would lead to an edge process. These findings reconcile several theories that have been postulated about the physics of metal/MoS${}_2$ interfaces and provide a framework to design future devices with lower contact resistances.

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Cited by in corpus (7)

• High Current Density in Monolayer MoS${}_2$ Doped by AlO${}_x$
• One-dimensional edge contacts to a monolayer semiconductor
• 2-D materials for ultra-scaled field-effect transistors: hundred candidates under the ab initio microscope
• Pinpointing the Dominant Component of Contact Resistance to Atomically Thin Semiconductors
• Combinatorial Large-area MoS2/Anatase-TiO2 interface: A Pathway to Emergent Optical and Opto-electronic Functionalities
• Dynamics of van der Waals Charge Qubit in 2D Bilayers: Ab initio Quantum Transport and Qubit Measurement
• Winterface: An Interface from Wannier90 to Quantum Transport