Defect-Induced Vibration Modes of Ar+ -Irradiated MoS2

Robust valley polarization of helium ion modified atomically thin MoS 2

“…19 Thus, an increase in σ to 10 14 cm −2 is expected to result in a steadily increasing density of monosulphur vacancies V 1S in the crystal. 34 A strong reduction of PL intensity is observed for σ > 10 14 cm −2 which as a consequence very likely results in enhanced Auger recombination through the introduction of high disorder in the crystal. This interpretation is in good agreement with large mode shifts in this dose range (σ > 10 14 cm −2 ) in the Raman data.…”

Excited‐State Charge Transfer in Covalently Functionalized MoS2 with a Zinc Phthalocyanine Donor–Acceptor Hybrid

“…The Raman spectrum (λ exc =633 nm) of 2 under on‐resonance conditions for MoS 2 , revealed not only characteristic modes for MoS 2 at 150–500 cm −1 but also bands attributed to ZnPc at 1150–1600 cm −1 . Raman bands centered at 451, 403, and 379 cm −1 (Figure a) are associated with the 2LA(M) mode due to disorder and defects, the out‐of‐plane A 1g vibrations of S, and the in‐plane vibrations of S and Mo, respectively. The location of and A 1g and in particular their frequency difference, which was calculated to be 24 cm −1 , is directly related to the thickness and number of layers of MoS 2 , showcasing the presence of few MoS 2 layers in 2 .…”

Recent Progress on Irradiation-Induced Defect Engineering of Two-Dimensional 2H-MoS2 Few Layers

“…To understand the irradiation-induced defects well, the synthesis/preparation details of the as-prepared MoS 2 layers will be described in each section in addition to irradiation. [75] mono-layer electron 60 keV 10 6 -10 9 electron /nm 2 STEM beam 400-700 • C in vacuum induced 2H/1T phase transition [76] ∼10 layer electron 3-15 keV n/a EPMA in vacuum broke the inversion symmetry [77] mono-layer electron 80 keV n/a TEM beam in vacuum removed top and bottom S atoms [78] mono-layer electron 200 keV 3000 electrons/nm 2 /s TEM beam in vacuum created S vacancies, increased electric resistance [79] mono-layer electron 15 keV 280 µC/cm 2 EBL in vacuum produced local strain and changed band structure [80] mono-layer electron 80 keV 40 A/cm 2 TEM beam in vacuum produced holes and Mo 5 S 3 nanoribbons [81] amorphous 5-7 layer electron 1 keV 1-10 min EBI in vacuum crystallized [82] mono-layer U 238 1.14 GeV 4000 ions/cm 2 heavy ion accelerator in vacuum total damaged [83] micron thickness Ar + 500 eV 2.26 × 10 15 ions/cm 2 plasma UHV produced S vacancies [84] bi-layer Ar + 500 eV 10 14 -10 15 ions/cm 2 plasma UHV produced S vacancies and MoS 6 vacancy clusters [84] mono-layer Ar + 500 eV 2.26 × 10 15 ions/cm 2 plasma UHV damaged [84] 200 µm thickness proton 3.5 MeV 5 × 10 18 ions/cm 2 Singletron facility RT preserved lattice structure, produced defects, changed magnetic moments [85] few-layer proton 10 MeV 10 12 -10 14 ions/cm 2 MC-50 cyclotron n/a decreased electrical conductance [86] mono-layer proton 100 keV 10 12 -10 15 particles/cm 2 LEAF n/a created defects [87] bi-layer proton 100 keV 6 × 10 14 particles/cm 2 LEAF n/a created defects [87] bulk He 2+ 1.66 MeV 900 MGy ion accelerator n/a changed Raman scattering slightly [88] nanosheet He 2+ 1.66 MeV 900 MGy ion accelerator n/a invariant [88] few-layer He 2+ 30 keV 10 18 ions/cm 2 FIB beam in vacuum milled or damaged [89] mono-layer He 2+ 3.04 MeV 8 × 10 13 particles/cm 2 PTA n/a produced defects [90] mono-layer He + 30 keV 10 12 -10 16 ions/cm 2 HIM in vacuum produced S vacancies [91] mono-layer He + 30 keV 10 13 -10 17 ions/cm 2 NFM in vacuum ...…”

“…Bae et al [84] MoS 2 prepared slabs with a thickness of several microns from MoS 2 crystals using the mechanical exfoliation method and then irradiated them with Ar + ions with an energy of 500 eV in an UHV, with fluences of 5.65 × 10 14 ions/cm 2 and 2.26 × 10 15 ions/cm 2 . The incident angle of Ar + was almost normal to the surface of the samples.…”

“…Raman spectra of (bottom) MoS 2 crystalline bulk, Ar + -irradiated MoS 2 micron crystals at fluences of (middle) 5.65 × 10 14 ions/cm 2 and (top) 2.26 × 10 15 ions/cm 2 [84]. Reprinted with permission from Reference [84]. Copyright c 2017 by the American Physical Society.…”