Swift-heavy ion irradiation-induced latent tracks in few- and mono-layer MoS2

Abstract

The latent tracks in mono-and few-layer molybdenum disulfide (MoS 2 ) induced by 209 Bi ions with energies of 0.45-1.23 GeV were characterized by atomic force microscopy (AFM). The hillock-like latent tracks were observed on the surface of irradiated monolayer MoS 2 . The diameter of the hillock after deconvolution procedure is 15.8 ± 1.7 nm and the height is 1.0 ± 0.3 nm. Hillock-like tracks are induced by energy transfer from energetic 209 Bi ions to electron system of MoS 2 , resulting in the ionization and excitation and then the displacement of target atoms. Since Raman spectroscopy is sensitive to damages induced by swift-heavy ion irradiation, the in-plane E 2g 1 mode (*385 cm -1 ) and the out-of-plane A 1g mode (*408 cm -1 ) of MoS 2 were investigated. With increasing ion fluence, the A 1g peak shifts to higher frequencies, and the intensity ratio between A 1g and E 2g 1 peak increases. Besides, the A 1g peak narrows. The evolution of the structural and vibrational properties of MoS 2 with fluence is discussed. It can be concluded that the blue shift and narrowing of A 1g peak in irradiated MoS 2 is due to the adsorption of oxygen molecules at latent tracks. With decreasing thickness of MoS 2 , the irradiation resistance decreases.

Highly active single-layer MoS2 catalysts synthesized by swift heavy ion irradiation

“…We can easily explain this by assuming that the edges of the incisions created by ions in MoS 2 provide additional catalytically active low-coordinated Mo atoms which are likely to oxidize when exposed to air. 46 Apart from these low-coordinated Mo atoms, we argue that SHI irradiation also creates S vacancies next to the incisions due to the thermal spike after ion impact because the lower sublimation temperature of S compared to Mo results in a preferential evaporation of S atoms in adjacent rows next to the ion trajectory. When analyzing the stoichiometry of Mo and S in the XPS data prior to and after irradiation using the XPS peak areas and the corresponding relative sensitivity factors (RSFs), 47 we indeed see a clear increase of the total Mo : S ratio.…”

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

“…Guo et al [102] deposited 1-4-layer-ed MoS 2 on silicon substrates capped with SiO 2 . The mechanically exfoliated MoS 2 nanosheets were irradiated by 209 Bi ions with energies of 0.45-1.23 GeV and fluences of 1 × 10 10 -3.6 × 10 12 ions/cm 2 in a vacuum at room temperature under normal incidence.…”

Generating Sub-nanometer Pores in Single-Layer MoS2 by Heavy-Ion Bombardment for Gas Separation: A Theoretical Perspective

“…All of these successful applications demonstrate ion beam bombardment to be a highly effective and economical way to fabricate nanopores in graphene and can be potentially applied to other two-dimensional materials. Although some previous works have studied the radiation effect of heavy ions in single-layer MoS 2 , − the creation of nanopores in single-layer MoS 2 by ion irradiation has not been systematically explored yet.…”