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Two-dimensional molybdenum disulfide (2D MoS2) has great application prospects in the field of optoelectronic devices. Defect engineering is an effective way to regulate the electronic and optical properties of 2D MoS2. However, defect controlling on 2D materials remains a major challenge. Fluorine, as the most electronegative element, may cause many interesting phenomena after doping in 2D materials. So far, there have been no reports on the effect of fluoride ion (F− ion) irradiation on 2D material properties. In this paper, the monolayer MoS2 (ML-MoS2) synthesized by the chemical vapor deposition method was taken as the research object, and defects with controllable densities were produced by 30 keV F− ion irradiation, in which the defects were dominated by S vacancies. Based on Raman, photoluminescence, and x-ray photoelectron spectroscopy, it is shown that the ion irradiation-induced defects significantly affect the optoelectronic properties of MoS2. We also observed the p-doping of ML-MoS2, which is attributed to the introduction of F− ions and the electron transfer from MoS2 to O2 at defect adsorption sites. This study reveals that 2D materials could be effectively doped or compensated using irradiation technology, potentially fabricating novel 2D electrical devices through defect engineering. [ABSTRACT FROM AUTHOR]

Wide bandgap β-Ga2O3 is an ideal candidate material with broad application prospects for power electronic components in the future. Aiming at the application requirements of β-Ga2O3 in space photoelectric devices, this work studies the influence of 40 MeV Si ion irradiation on the microstructure and optical properties of β-Ga2O3 epi-wafers. Raman spectroscopy analysis confirms that Si ion irradiation destroys the symmetric stretching mode of tetrahedral–octahedral chains in β-Ga2O3 epi-wafers, and the obtained experimental evidence of irradiation leads to the enhanced defect density of VO and VGa–VO from x-ray photoelectron spectroscopy. Combined with first-principles calculations, we conclude that most configurations of VO and VGa–VO are likely non-radiative, leading to quenching of experimental photoluminescence intensity. Unraveling optical degradation mechanism and predicting the optical application of β-Ga2O3 devices in the space environment by combining ground irradiation experiments with first-principles calculations still be one of the focuses of research in the future. [ABSTRACT FROM AUTHOR]