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Angstrom-Size Defect Creation and Ionic Transport through Pores in Single-Layer MoS2
journal contribution
posted on 2018-02-21, 00:00 authored by Jothi
Priyanka Thiruraman, Kazunori Fujisawa, Gopinath Danda, Paul Masih Das, Tianyi Zhang, Adam Bolotsky, Néstor Perea-López, Adrien Nicolaï, Patrick Senet, Mauricio Terrones, Marija DrndićAtomic-defect engineering
in thin membranes provides opportunities
for ionic and molecular filtration and analysis. While molecular-dynamics
(MD) calculations have been used to model conductance through atomic
vacancies, corresponding experiments are lacking. We create sub-nanometer
vacancies in suspended single-layer molybdenum disulfide (MoS2) via Ga+ ion irradiation, producing membranes
containing ∼300 to 1200 pores with average and maximum diameters
of ∼0.5 and ∼1 nm, respectively. Vacancies exhibit missing
Mo and S atoms, as shown by aberration-corrected scanning transmission
electron microscopy (AC-STEM). The longitudinal acoustic band and
defect-related photoluminescence were observed in Raman and photoluminescence
spectroscopy, respectively. As the irradiation dose is increased,
the median vacancy area remains roughly constant, while the number
of vacancies (pores) increases. Ionic current versus voltage is nonlinear
and conductance is comparable to that of ∼1 nm diameter single
MoS2 pores, proving that the smaller pores in the distribution
display negligible conductance. Consistently, MD simulations show
that pores with diameters <0.6 nm are almost impermeable to ionic
flow. Atomic pore structure and geometry, studied by AC-STEM, are
critical in the sub-nanometer regime in which the pores are not circular
and the diameter is not well-defined. This study lays the foundation
for future experiments to probe transport in large distributions of
angstrom-size pores.
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future experimentsvacancy areaAtomic pore structureirradiation doseprobe transportsub-nanometer regimeangstrom-size poresMD simulations showMoS 2Angstrom-Size Defect Creationion irradiationS atomssub-nanometer vacanciessingle-layer molybdenum disulfidediameteraberration-corrected scanning transmission electron microscopyIonic Transportphotoluminescence spectroscopymodel conductance1200 poresMoS 2 poresVacancies exhibitnmdistribution displayAC-STEMdefect-related photoluminescenceSingle-Layer MoS 2 Atomic-defect engineering
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