  The combination of high-quality Al2O3 dielectric and thiol chemistry
passivation can effectively reduce the density of interface traps and Coulomb
impurities of WS2, leading to a significant improvement of the mobility and a
transition of the charge transport from the insulating to the metallic regime.
A record high mobility of 83 cm2/Vs (337 cm2/Vs) is reached at room temperature
(low temperature) for monolayer WS2. A theoretical model for electron transport
is also developed.
