High Performance Multilayer
MoS<sub>2</sub> Transistors
with Scandium Contacts
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Abstract
While there has been growing interest in two-dimensional
(2-D)
crystals other than graphene, evaluating their potential usefulness
for electronic applications is still in its infancy due to the lack
of a complete picture of their performance potential. The focus of
this article is on contacts. We demonstrate that through a proper
understanding and design of source/drain contacts and the right choice
of number of MoS<sub>2</sub> layers the excellent intrinsic properties
of this 2-D material can be harvested. Using scandium contacts on
10-nm-thick exfoliated MoS<sub>2</sub> flakes that are covered by
a 15 nm Al<sub>2</sub>O<sub>3</sub> film, high effective mobilities
of 700 cm<sup>2</sup>/(V s) are achieved at room temperature. This
breakthrough is largely attributed to the fact that we succeeded in
eliminating contact resistance effects that limited the device performance
in the past unrecognized. In fact, the apparent linear dependence
of current on drain voltage had mislead researchers to believe that
a truly Ohmic contact had already been achieved, a misconception that
we also elucidate in the present article