  Improving carrier mobilities of two-dimensional (2D) semiconductors is highly
sought after. Recently, Ng. et al. [1] reported rippled molybdenum disulfide
(MoS$_2$) transistors on bulged silicon nitride (SiN$_x$) substrates that
exhibit high electron mobilities up to ~900 cm$^2$V$^{-1}$s$^{-1}$. The high
mobility values were attributed to the suppression of electron-phonon
scattering by the lattice distortion in the rippled MoS$_2$ channel. While the
results are compelling, this Matters Arising shows that the mobility values in
ref. [1] are likely to be overestimated due to invasive voltage probes in the
four-probe measurement setup, which causes a positive threshold voltage shift
near the voltage probes and an artificial overestimation of apparent
field-effect mobility.
