Abstracts Book - IMRC 2018

• SA3-O005 Invited Talk
TUNING THE TRANSPORT PROPERTIES OF WSe2 2d MATERIALS
Philip Rack 1,2
1 Oak Ridge National Laboratory, Center for Nanophase Materials Science, United States. 2 The
University of Tennessee, Materials Science and Engineering, United States.
Transition metal dichalgogenide (TMD) materials are intriguing layered
materials with finite band gaps, which make them interesting candidates for
electronic and optoelectronic applications. In addition to the usual anion and
cation alloying for tuning the band gap, one can also tune the band gap based
on the number of TMD layers. In our group, we have focused on various
methods to explore and control the transport properties in primarily
WSe2. Conveniently WSE2 is ambipolar, and we will show that the dominant
carrier type can be controlled via the number of layers and judicious choices of
the metal work function. In addition, we will overview our work utilizing the
helium gas field ion microscope as a nanoscale direct write method to introduce
defects into the WSe2 and further control the transport behavior in both
multilayer and single layer WSe2 devices. A semiconductor to insulator to
pseudo-metallic transition occurs with increasing He + flux (ranging ~ 1x10 13
to1x10 16 He + /cm 2 ). The He + preferentially sputters selenium and the resultant
selenium vacancies at low concentration are n-type dopants and at higher
concentrations form a percolating network of states and thus have pseudometallic
transport. Direct write resistor loaded inverters and edge contacted
transistors have been achieved towards atomically thin 2D circuitry. Finally, we
have explored gas-assisted focused He+ etching of WSe2 nanoribbons and have
achieved sub 10 nm resolution.
Acknowledgment:
PDR acknowledges support support by US Department of Energy (DOE) under
Grant No. DOE DE-SC0002136 and a portion of this work was supported by the
U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials
Sciences and Engineering Division and performed in part as a user project at the
Center for Nanophase Materials Sciences.
Keywords: Transition metal dichalcogenide, atomic ciruits, electronic devices
Presenting authors email: prack@utk.edu