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Defect Engineering in Single-Layer MoS2 Using Heavy Ion Irradiation
摘要： Transition metal dichalcogenides (TMDs) have attracted much attention due to their promising optical, electronic, magnetic, and catalytic properties. Engineering the defects in TMDs represents an effective way to achieve novel functionalities and superior performance of TMD devices. However, it remains a significant challenge to create defects in TMDs in a controllable manner or to correlate the nature of defects with their functionalities. In this work, taking single-layer MoS2 as a model system, defects with controlled densities are generated by 500 keV Au irradiation with different ion fluences, and the generated defects are mostly S vacancies. We further show that the defects introduced by ion irradiation can significantly affect the properties of the single-layer MoS2, leading to considerable changes in its photoluminescence characteristics and electrocatalytic behavior. As the defect density increases, the characteristic photoluminescence peak of MoS2 first blueshifts and then redshifts, which is due to the electron transfer from MoS2 to the absorbed O2 at the defect sites. The generation of the defects can also strongly improve the hydrogen evolution reaction activity of MoS2, attributed to the modified adsorption of atomic hydrogen at the defects.
关键词： PL,defect engineering,Raman,ion beam,MoS2
更新于2025-09-10 09:29:36
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Researches on formation mechanism of ultra-smooth surface during ion beam sputtering of fused silica
摘要： Ion beam ?guring (IBF) is well identi?ed as a highly deterministic method for the ?nal ?guring of nanometer-precision optical surfaces, where the ?guring process involves an atomic/molecular material removal mechanism by using ion beam sputtering (IBS). However, IBS-induced na-noscale phenomena make the ultra-smooth surface formation process full of uncertainties that these phenomena would seriously in?uence the fabrication of high-performance optical com-ponents. In this work, the microscopic morphology evolution theories, including the IBS-induced microscopic behaviors and microscopic material densi?cation dependent sputtering, are in-vestigated to discuss the ultra-smooth surface manufacturability of fused silica. Our research results indicate that IBS-induced nanostructuring behaviors can be used for the preparation of ultra-smooth surfaces, which requires smoothing e?ects dominate over sputtering roughening during the surface morphology evolution. Meanwhile, we ?nd that IBS is very sensitive to the change of the microscopic material properties, and speci?cally the ultra-smooth manufacturing process would be seriously a?ected when the surface/subsurface damages are generated in the former machining procedure. To control the microscopic material change and achieve ultra-smooth surface, a combined manufacturing technology including chemical-mechanical polishing (CMP) and IBF is proposed. Through the experimental investigation, fused silica with surface roughness down to 0.1nm root mean square (RMS) level is obtained by using this combined technology, which demonstrates the feasibility of our proposed method.
关键词： Surface microscopic behavior,Ion beam sputtering,Ultra-smooth surface
更新于2025-09-10 09:29:36
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Materials Science and Technology of Optical Fabrication || Novel Polishing Methods
摘要： In this chapter, some novel polishing methods are brie?y discussed and related to principles and phenomena outlined in Chapters 2–5. Details of these polishing methods and capabilities are well described in the broad literature, and hence not covered here.
关键词： Convergent Polishing,Magnetorheological Finishing,Ion Beam Figuring,Tumble Finishing,Float Polishing,Novel Polishing Methods
更新于2025-09-10 09:29:36
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Precise sputtering of silicon dioxide by argon cluster ion beams
摘要： In this work, the sputtering yields of SiO2 by the argon cluster ion beam with incident angles 0° and 45° have been studied experimentally. The kinetic energy of the primary cluster ions was in the range of E = 5–23.5?keV, and the mean cluster size was Nmean = 100–1000 atom/cluster. It is found that, when the energy per cluster atom quantity E/N is comparable to the binding energy of the solid (of the order of several eV), the yields of atoms sputtered per primary atom Y/N, at the incident angle 45°, is 4 times greater than at normal incidence. Conversely, when energy E/N is significantly above the binding energy of the solid (~ 100?eV), the sputtering yields for the incident angles 0° and 45° have the same values.
关键词： kinetic energy,incident angles,argon cluster ion beam,sputtering yields,cluster size,silicon dioxide
更新于2025-09-10 09:29:36
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Photocurrent enhancement on TiO2 nanotubes co-modified by N+ implantation and combustion of graphene
摘要： Nitrogen ions doped TiO2 nanotubes (N-TNTs) were synthesized via ion implantation and anodization. Graphene was deposited on the surface of N-TNTs during anodization. After being annealed at the temperature of 450 °C, the samples were determined using FE-SEM, XRD, XPS, and UV-Vis DRS. The photoelectric performance of the samples was confirmed by transient photocurrent. The results indicated that morphology and structure of N-TNTs were improved due to ion implantation. Because of the combustion of deposited graphene during the annealing process, the degree of crystallinity of N-TNTs was improved, and the contents of substitutional N increased. The TNTs modified by ion implantation and combustion of graphene exhibited the best photoelectric performance.
关键词： Visible light,TiO2 nanotubes,Carbon materials,Ion beam technology,Photoelectric properties
更新于2025-09-10 09:29:36
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Optical and Magneto-Optical Properties of Multilayer Nanosized [Co/TiO2]n Films
摘要： The optical and magneto-optical properties of the metal–dielectric multilayer [Co/TiO2]n structures with 2–4-nm-thick layers prepared on a silicon substrate Si(001) by ion-beam deposition have been studied. The complex permittivity of multilayer [Co/TiO2]n structures has been measured by the optical ellipsometry technique in the spectral range of 0.6–5.6 eV and analyzed using the optical reflection matrices for isotropic multilayer dielectric structures taking into account the optical losses and also using the method of anisotropic effective medium. The magneto-optical Kerr effect has been measured by the polarimetric technique in the spectral range of 1.2–4.5 eV in the polar and longitudinal geometries. The magnetic anisotropy type is determined on the base of the field dependences of the magneto-optical Kerr effect. It is found that the nanosized [Co/TiO2]n structures can be considered as artificial optically uniaxial media with a strong magnetic and optical anisotropy at room temperature.
关键词： silicon substrate,Co/TiO2,magneto-optical properties,multilayer nanosized films,optical properties,complex permittivity,magneto-optical Kerr effect,magnetic anisotropy,optical ellipsometry,ion-beam deposition
更新于2025-09-10 09:29:36
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Direct writing of single germanium vacancy center arrays in diamond
摘要： Single photon emitters in solid-state systems with superior optical properties are of fundamental importance for they are building block candidates of many quantum optics applications. The ideal qubit will have a bright narrow band emission (i.e. high Debye Waller (DW) factor) and an access to optically read out and manipulate its spin states. Numerous candidates have been studied in diamond including the nitrogen vacancy (NV) center and more recently the silicon vacancy (SiV) center. The advantage of the SiV is its high DW factor, with nearly 80% of its emission is within its zero phonon line (ZPL). But its coherence time is limited by the narrow ground state splitting (~40 GHz) which favors single-phonon absorption from the lower branch to the upper one. This necessitates the search for an alternative system with a larger ground state splitting to suppress the phonon-mediated processes. Color centers in diamond are promising solid-state qubits for scalable quantum photonics applications. Amongst many defects, those with inversion symmetry are of an interest due to their promising optical properties. In this work, we demonstrate a maskless implantation of an array of bright, single germanium-vacancy (GeV) centers in diamond. Employing the direct focused ion beam technique, single GeV emitters are engineered with the spatial accuracy of tens of nanometers. The single GeV creation ratio reaches as high as 53% with the dose of 200 Ge+ ions per spot. The presented fabrication method is promising for future nanofabrication of integrated photonic structures with GeV emitters as a leading platform for spin-spin interactions.
关键词： diamond,germanium-vacancy centers,single photon emitters,quantum photonics,focused ion beam
更新于2025-09-09 09:28:46
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Simple Fabrication of Pillar Silicon Nanostructures by a Contact Block Copolymer Technique
摘要： In this study, silicon nanopillar structures were fabricated by a contact block copolymer (BCP) technique, which is a potential technique for the fabrication of self-aligned silicon nanoscale structures. For the contact BCP technique, a nanometer-scale BCP hole pattern was formed on the silicon surface and the silicon, masked with BCP, was exposed to a nitrogen ion beam for surface nitriding. Using the nitride surface as the etch mask, after the removal of the BCP silicon nanopillar structures could be successfully fabricated using a low-energy chlorine-based ion beam. By eliminating the additional steps of hard mask deposition and etching, this technique provided a simplified method of forming a silicon nanostructure. Especially, due to the extremely low thickness of the nitride mask layer, precise transfer of the mask dimension to the silicon was possible. The use of a low-energy ion beam could not only minimize the damage to the nanopillar silicon surface but could also increase the etch selectivity.
关键词： Block Copolymer,Inverted Ion Beam Etching,Pillar-Type Silicon Nanostructure,Surface Nitriding
更新于2025-09-09 09:28:46
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Ion Beam Defect Engineering on ReS <sub/>2</sub> /Si Photocathode with Significantly Enhanced Hydrogen Evolution Reaction
摘要： Loading 2D layered transition metal dichalcogenides (TMDs) on p-type silicon photocathode is suitable for hydrogen production in solar-driven photoelectrochemical (PEC) water splitting. Similarly, various nanostructured TMDs exposing more active sites are widely explored for improving the PEC performances of composite photoelectrodes. Here, defect engineering using a controllable argon ion beam bombardment is presented on ReS2/Si photocathode. The atomic vacancy defects are introduced on the 2D ReS2 to realize high-density active sites, which significantly enhance the solar-driven hydrogen evolution reaction performance of ReS2/Si photocathode. The highest photocurrent density of 18.5 mA cm?2 (at 0 V vs reversible hydrogen electrode) is achieved, under a simulated sun irradiation.
关键词： ion beam bombardment,defect engineering,photocathodes,photoelectrochemical water splitting,ReS2
更新于2025-09-09 09:28:46
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Electroluminescence of intrashell transitions in Eu doped single ZnO nanowires
摘要： Tunable nanoscale light emitters are essential to accomplish future multifunctional optoelectronic nano-devices. Here, we present an approach for achieving red electroluminescence from single ZnO nanowires implanted with Europium ions. The electroluminescence is emitted mainly from the end facets of ZnO nanowires at room temperature under the application of an AC voltage. The corresponding electroluminescence spectrum is attributed to the radiative intrashell transitions of the Eu ions, while contributions from near band edge or deep level emission of the ZnO remain absent. The total intensity of the electroluminescence is linearly proportional to the length of the nanowires, whereas there is no clear correlation with other morphology factors of the nanowire based device such as the diameter. Furthermore, the underlying excitation mechanism of the electroluminescence is proposed as direct-impact excitation of Eu ions by hot electrons in the ZnO nanowires.
关键词： electroluminescence,Zinc oxide (ZnO),Europium (Eu),nanowires,rare earth elements,ion beam doping
更新于2025-09-09 09:28:46