  Monolayer transition metal dichalcogenides recently emerge as a new family of
two-dimensional material potentially suitable for numerous applications in
electronic and optoelectronic devices due to the presence of finite band gap.
Many proposed applications require efficient transport of charge carriers
within these semiconducting monolayers. However, how to construct a stable
conducting nanoroad on these atomically thin semiconductors is still a
challenge. Here we demonstrate that hydrogenation on the surface of MoS2
monolayer induces a semiconductor-metal transition, and strip-patterned
hydrogenation is able to generate a conducting nanoroad. The band-gap closing
arises from the formation of in-gap hybridized states mainly consisting of Mo
4d orbitals, as well as the electron donation from hydrogen to the lattice
host. Ballistic conductance calculations reveal that such a nanoroad on the
MoS2 surface exhibits an integer conductance, indicating small carrier
scattering, and thus is ideal for serving as a conducting channel or
interconnect without compromising the mechanical and structural integrity of
the monolayer.
