Gamma Radiation-Induced Oxidation, Doping, and Etching of Two-Dimensional MoS₂ Crystals

Abstract

Two-dimensional (2D) MoS 2 is a promising material for future electronic and optoelectronic applications. 2D MoS 2 devices have been shown to perform reliably under irradiation conditions relevant for a low Earth orbit. However, a systematic investigation of the stability of 2D MoS 2 crystals under high-dose gamma irradiation is still missing. In this work, absorbed doses of up to 1000 kGy are administered to 2D MoS 2 . Radiation damage is monitored via optical microscopy and Raman, photoluminescence, and X-ray photoelectron spectroscopy techniques. After irradiation with 500 kGy dose, p-doping of the monolayer MoS 2 is observed and attributed to the adsorption of O 2 onto created vacancies. Extensive oxidation of the MoS 2 crystal is attributed to reactions involving the products of adsorbate radiolysis. Edge-selective radiolytic etching of the uppermost layer in 2D MoS 2 is attributed to the high reactivity of active edge sites. After irradiation with 1000 kGy, the monolayer MoS 2 crystals appear to be completely etched. This holistic study reveals the previously unreported effects of high-dose gamma irradiation on the physical and chemical properties of 2D MoS 2 . Consequently, it demonstrates that radiation shielding, adsorbate concentrations, and required device lifetimes must be carefully considered, if devices incorporating 2D MoS 2 are intended for use in high-dose radiation environments.

2D Magnetic Semiconductor Fe3GeTe2 with Few and Single Layers with a Greatly Enhanced Intrinsic Exchange Bias by Liquid-Phase Exfoliation

“…Raman spectra (Figure b) of FGT present three main vibration peaks (E 2g 1 , E 2g 2 , and A 1g 1 ). , FGT nanoflakes mainly vibrate as in-plane vibrations of the Fe, Ge, and Te ions (E 2g 2 ), rather than in-layer reverse mode (E 2g 1 ) like FGT crystals. The blue shift of the E 2g mode after exfoliation is similar to that of other 2D materials, , which is due to the increase of surface force constant arising from the slight charge redistribution with the reduction of adjacent layers . The out-of-plane vibration mode A 1g 1 is also sensitive to the number of layers, and shows a red-shift phenomenon because of the decrease of the effective restoring force caused by the weakening of the vdW forces between adjacent layers .…”

“…The blue shift of the E 2g mode after exfoliation is similar to that of other 2D materials, 74,75 which is due to the increase of surface force constant arising from the slight charge redistribution with the reduction of adjacent layers. 76 The out-of-plane vibration mode A 1g 1 is also sensitive to the number of layers, and shows a red-shift phenomenon because of the decrease of the effective restoring force caused by the weakening of the vdW forces between adjacent layers. 77 Clean and clear nanoflakes are observed by an optical microscope (OM) (Figure 3c).…”

Angstrom-scale ion channels towards single-ion selectivity

“…5D). 115,116 Through a polymethyl methacrylate-assisted transfer, a single-layered MoS 2 nanosheet was transferred onto carbon grids. Atomic vacancy defects on the nanosheet were introduced by the Ga + ion irradiation using a focused ion beam.…”

Gamma-Ray Irradiation Induced Ultrahigh Room-Temperature Ferromagnetism in MoS2 Sputtered Few-Layered Thin Films

“…Extensive investigations have been carried out to demonstrate the effects of exposure to deep ultraviolet light, neutron, electron, , proton, , and gamma-ray irradiation , on the electronic and optical properties of TMDs. However, only a few studies have evaluated irradiation-induced magnetism in TMDs. − Mathew et al observed that proton irradiated (2 MeV) MoS 2 flakes (200 μm) exhibited a ferrimagnetic behavior, and its origin has been explained based on vacancy clusters, isolated vacancies, and the formation of edge structures .…”