Effective n-type doping of monolayer MoS2 by AlOx

Doping of two-dimensional (2D) semiconductors often utilizes charge transfer techniques that are not compatible with standard CMOS fabrication and are unstable over time. Sub-stoichiometric oxides have demonstrated stable 2D material doping [1], but often degrade the subthreshold swing (S) and current on/off ratio (I_max/I_min) of a device. Here, we demonstrate that AlO_x can n-dope monolayer (1L) MoS₂ while preserving I_max/I_min and S. The AlO_x doping significantly reduces the contact resistance (to 480 Ω·μm) while preserving the mobility (~34 cm²V^-1s^-1) and S, ultimately achieving record on-current of 700 μA/μm for a monolayer semiconductor. We also present a model for the effect of interface traps on the transfer characteristics, which explains the experimentally obtained results.