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Download fileElectron Transport through Metal/MoS2 Interfaces: Edge- or Area-Dependent Process?
journal contribution
posted on 2019-05-13, 00:00 authored by Áron Szabó, Achint Jain, Markus Parzefall, Lukas Novotny, Mathieu LuisierIn
ultrathin 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 MoS2, both short (≤30 nm) and long (≥0.5 μm)
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 ab initio quantum
transport simulations to demonstrate that the presence of an oxide
layer between a metallic contact and a MoS2 monolayer,
for example, TiO2 in the 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/MoS2 interfaces and provide
a framework to design future devices with lower contact resistances.