Atomic Layer Engineering of TMDs by Modulation of Top Chalcogen Atoms: For Electrical Contact and Chemical Doping

To achieve high-performance electronic and optoelectronic devices based on two-dimensional transition-metal dichalcogenides (2D TMDs), it is necessary to solve the contact resistance issue caused by the energy barrier at the interface between metal electrodes and the 2D semiconductor. By use of a controlled Ar+ ion beam with a threshold ion energy of 25 eV, the top sulfur layer only was successfully removed from the monolayer molybdenum disulfide (MoS2), and the semiconductor to metallic transition (MT) of MoS2 could be achieved, thus minimizing the contact resistance issue. In addition, through nitrogen atomic doping on the unstable MoS obtained after the removal of the top sulfur layer using a controlled N+/N2+ ion beam, the transformation to the p-type branch could be obtained in the I–V curve. It is believed that this atomic rearrangement technology can overcome the limitations of advanced 2D semiconductors for electronic and optoelectronic devices by replacing and rearranging atoms and functional groups in the covalent bonding.