  In practical electronic applications, where doping is crucial to exploit
large-area two-dimensional (2D) semiconductors, surface charge transfer doping
(SCTD) has emerged as a promising strategy to tailor their electrical
characteristics. However, impurity scattering caused by resultant ionized
dopants, after donating or withdrawing carriers, hinders transport in 2D
semiconductor layers, limiting the carrier mobility. Here, we propose a
diffusion doping method for chemical vapor deposition (CVD) grown molybdenum
disulfide that avoids interference from charged impurities. Selectively
inkjet-printed dopants were introduced only on the contact region, allowing
excessively donated electrons to diffuse to the channel layer due to the
electron density difference. Therefore, diffusion-doped molybdenum disulfide
FETs do not have undesirable charged impurities on the channel, exhibiting over
two-fold higher field-effect mobility compared with conventional direct-doped
ones. Our study paves the way for a new doping strategy that simultaneously
suppresses charged impurity scattering and facilitates the tailoring of the
SCTD effect.
