# Recent Progress on Irradiation-Induced Defect Engineering of Two-Dimensional 2H-MoS2 Few Layers
## 1 Introduction
### Irradiated MoS\({}_{2}\) Materials
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**MoS\({}_{2}\)** & **Iradiation** & **Particle Energy** & **Dose/fluence** & **Iradiation Source** & **Iradiation Conditions** & **Results** & **Ref.** \\ \hline
200 nm & Ar\({}^{+}\) & 180 keV & 10\({}^{33}\)-10\({}^{27}\) ions/cm\({}^{2}\) & IBAD & 200 \({}^{\circ}\)C in vacuum & induced amorphiation & [93] \\ \hline bi-layer & Ar\({}^{+}\) & 500 eV & 10\({}^{41}\)-10\({}^{53}\) ions/cm\({}^{2}\) & n/a & UHV & produced S vacancies at low doses and Mo/Mo\({}_{8}\) & [84] \\ \hline mono-layer & Ar\({}^{+}\) & 500 eV & 10\({}^{41}\)-10\({}^{53}\) ions/cm\({}^{2}\) & n/a & UHV & vacancies at high doses & [84] \\ \hline mono-layer & Ar\({}^{+}\) & 500 eV & 3-11 nA/cm\({}^{2}\) & sputter beam & vacuum & selectively removed S atoms without significantly depleted Mo atoms & [84] \\ \hline mono-layer & Ar\({}^{+}\) & 135.58 MHz & n/a & RF plasma & RT & produced 217/17 phase transition & [97] \\ \hline mono-layer & Ga ion & n/a & n/a & PAMBE & 450 \({}^{\circ}\)C in vacuum & doped Ca, reduced binding energy & [98] \\ \hline mono-layer & Ga ion & 30 keV & 10\({}^{31}\) ion/cm\({}^{2}\) & FIB beam & in vacuum & produced sub-nm pores and vacancies & [99] \\ \hline bulk & Xe & 91 MeV & 10 ions/sm\({}^{2}\) & GANIL & n/a & formed nano-hillocks & [100] \\ \hline few-layer & Xe & 91 MeV & 15 ions/sm\({}^{2}\) & GANIL & n/a & formed nano-incissions & [100] \\ \hline mono-layer & Xe ion & 91 MeV & 15 ions/sm\({}^{2}\) & GANIL & n/a & formed nano-incissions & [100] \\ \hline mono-layer & Xe ion & 25-30 keV & 10\({}^{30}\) cm\({}^{2}\) & EBIT & n/a & induced pits and hillocks & [101] \\ \hline
1-4 layer & Bi ion & 0.45-123 GeV & 10\({}^{30}\)-10\({}^{31}\) ions/cm\({}^{2}\) & HIFEL & vacuum, RT & formed hillocks & [102] \\ \hline mono-layer & Mn ion & 25 keV & 10\({}^{31}\)-10\({}^{34}\) ions/cm\({}^{2}\) & TOF-SMS & UHV & formed defects & [103] \\ \hline bulk & Ca\({}_{0}\) & 20-40 MeV & 10\({}^{36}\)-10\({}^{31}\) ions/cm\({}^{2}\) & TA & RT & modified structures & [104] \\ \hline micron thickness & \(\gamma\)-ray & n/a & \(5\times 10^{7}\) R & RGF & in air & no damaging effects & [105] \\ \hline
50-132 layer & \(\gamma\)-ray & 662 keV & 5000 photons & 13\({}^{27}\)Cs source & RT in air & unaffected & [106] \\ \hline
5-8 layer & \(\gamma\)-ray & \(\sim\)12 MeV & 120 Mrad & \({}^{46}\)Co source & RT in air & converted to Mo\({}_{0}\) & [107] \\ \hline
1-3 layer & X-ray & 10 keV & 68 hard & XRD & RT in air & no no achievable degradation & [108] \\ \hline film & UV & n/a & 0/a & mercury lamp & n\({}_{0}\) (zone) & formed oxygen-sulfur bonds & [109] \\ \hline mono-layer and multilayer & UV & n/a & 10\({}^{31}\)-10\({}^{39}\) photons/cm\({}^{2}\) & deuterium lamp & vacuum & no structural damage, no oxidation & [110] \\ \hline multilayer & laser & \(\lambda=514\) nm & 1-20 mW for 1-100 s & laser & RT in air & stable or damage depending on laser power & [111] \\ \hline few-layer & laser & \(\lambda=532\) nm & 300 mW & diode laser & in air or vacuum & patterned and thinned & [112] \\ \hline mono-layer & laser & \(\lambda=800\) nm & 20-50 mJ/cm\({}^{2}\) & Tsapphire laser & RT & damped or unaffected depending on irradiation intensity & [113] \\ \hline EBI-electron-beam irradiation, EBI-electron-beam ion trap, EBI-electron-beam lithography system; EEMA-electron probe micro-analyzer; FIB: focused ion beam; GANIL: The Grand Accelerateer National 4 JG Ion Controls (Large Heavy Ion; In National Accelerator); HIRL helium-ion microscope; HIRFL: heavy ion Research facility in Lamzhou; IBAD: ion-beam assisted deposition; LEAF: low-energy accelerator facility; NMR: Nano-AB microscope; PAMIE: plasma-assisted molecular beam epitaxy; THz: Reflection tandem accelerator; RF: radio frequency; RGF: Reactor Gamma Irradiation Facility; IR: room temperature; 5: sulfur; SEM: scanning electron microscope; STEM: scanning transmission electron microscope; STM: scanning tunneling microscope; TA: Tandem accelerator; TEM: transmission electron microscope; TOF-SMS: time-of-flight secondary ion mass spectrometer; UHV: ultra-high vacuum; XRB: X-ray diffractometer. & & & \\ \hline \end{tabular}
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