  The doping and strain effects on the electron transport of monolayer MoS_2
are systematically investigated using the first-principles calculations with
Boltzmann transport theory. We estimate the mobility has a maximum 275
cm^2/(Vs) in the low doping level under the strain-free condition. The applying
a small strain (3%) can improve the maximum mobility to 1150 cm^2/(Vs) and the
strain effect is more significant in the high doping level. We demonstrate that
the electric resistance mainly due to the electron transition between K and Q
valleys scattered by the M momentum phonons. However, the strain can
effectively suppress this type of electron-phonon coupling by changing the
energy difference between the K and Q valleys. This sensitivity of mobility to
the external strain may direct the improving electron transport of MoS_2.
