Defect-Dominated Doping and Contact Resistance in MoS2

Result date: 01/01/2014
Author: S. McDonnell
Institute: Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, United States
Publication: ACS Nano
Instrument: EA 125, MBE Systems, Multi-Chamber System, MULTIPROBE MXPS
Achieving low resistance contacts is vital for the realization of nanoelectronic devices based on transition metal dichalcogenides. We find that intrinsic defects in MoS2 dominate the metal/MoS2 contact resistance and provide a low Schottky barrier independent of metal contact work function. Furthermore, we show that MoS2 can exhibit both n-type and p-type conduction at different points on a same sample. We identify these regions independently by complementary characterization techniques and show how the Fermi level can shift by 1 eV over tens of nanometers in spatial resolution. We find that these variations in doping are defect-chemistry-related and are independent of contact metal. This raises questions on previous reports of metal-induced doping of MoS2 since the same metal in contact with MoS2 can exhibit both n- and p-type behavior. These results may provide a potential route for achieving low electron and hole Schottky barrier contacts with a single metal deposition.