离子束诱发沉积Pt纳米结构的研究

文章采用聚焦离子束诱发沉积的方法在Si表露制备了周期性的Pt纳米结构,利用扫描电子显微镜研究了离子束流和沉积时间对纳米结构的影响。本研究对于实现纳米结构的可控沉积具有学术参考价值。     

Improvement of Porous Si Luminescence Intensity Durability by Nitrogen Ion Irradiation Using an ECR Ion Source

We have investigated the effects of the porous Si surface passivation by oxygen or nitrogen ion processing on the photoluminescence (PL) intensity and its stability using an electron cyclotron resonance ion source. The results indicate that an anneal before exposure to ion beam causes a PL intensity enhancement upon exposure to oxygen or nitrogen ion beam. A combination of an anneal and a passivation by exposure to nitrogen ion beam enhances the PL intensity by a factor of 2.5 compared to the intensity of the initial as-anodized PS and the enhanced intensity is stabilized for more than 180 min under Ar⁺-laser illumination while oxygen-ion-exposed PS exhibits an enhancement in PL intensity only by 1.4 and a decay in PL intensity by 20% after 180 min Ar⁺-laser illumination. The results suggest that the reaction of nitrogen with a PS surface plays a key role for the PL intensity enhancement and stability.     

Effect of Ion Beam Irradiation on Two Nanofiltration Water Treatment Membranes

Abstract

Ion beam irradiation has long been recognized as an effective method for the synthesis and modification of diverse materials, including polymers. Ion beam irradiation is the bombardment of a substance with energetic ions. When the ions penetrate through the surface of a membrane, they may eliminate tall peaks and deep valleys, resulting in an overall reduction in surface roughness. Two nanofiltration membranes, one with a sulfonated polysulfone selective layer and the other with an aromatic polyamide selective layer, were used to study the effects of ion beam irradiation on surface morphology, microstructure, and performance. A beam of 25 keV H⁺ ions with four irradiation fluences (1 × 10¹³ ions/cm², 5 × 10¹³ ions/cm², 1 × 10¹⁴ ions/cm² and 5 × 10¹⁴ ions/cm²) was used for ion beam irradiation of the membrane. Atomic face microscopy (AFM) analysis show that the roughness of the membranes decreased after irradiation. An increase in flux after ion beam irradiation was also observed. Hydrophobicity, pore size distribution, and selectivity of the membrane were not affected by ion beam irradiation.     

微米／纳米加工中的聚焦离子束技术

聚焦离子束系统正成为微细加工领域的有力工具。文章简述了聚焦离子束系统的组成和工作原理,着重介绍了该系统在离子束刻蚀、离子束辅动沉积和离子注入等微米／纳米加工领域的应用,并对聚焦离予束技术的特点及未来的发展前景进行了总结和分析。     

Ion beam induced luminescence maps in CVD diamond as obtained by coincidence measurements

A new theory is presented concerning both IBIC (ion beam induced charge) and IBIL (ion beam induced luminescence) as obtained by a few MeV ion microbeam of a few micrometers spot size. The theory evidences the fact that IBIL depends on the ratio between the total carrier lifetime and the radiative recombination lifetime. The IBIL/IBIC maps, as obtained by dividing the two average signals pixel by pixel, depend only on radiative lifetime. IBIL maps, as obtained by coincidence measurements in order to avoid electric noise and display regions of low luminescence, compared with IBIC maps, indicate for the first time that regions of long collection length and regions of strong radiative recombination are the most important in CVD diamond. In conclusion, recombination in CVD diamond seems to be mainly radiative.     

Ion beam irradiation of few-layer graphene and its application to liquid crystal cells

Few-layer graphene was irradiated with a low-energy Ar⁺ ion beam and applied to liquid crystal (LC) cells as both a transparent electrode and a homogeneous alignment enhancer. The optimum conditions for ion-beam-irradiated few-layer graphene (I-G) are 80 eV of beam energy and 1 s of irradiation time, which is confirmed by the decrease of the sheet resistance and increase of water contact angle with similar transmittance to pristine few-layer graphene. It is shown that the ion beam treatment of few-layer graphene under optimized conditions removes the surface contaminants and flattens the surface without damages. LC cells on I-G show similar device performance to that of LC cells based on indium tin oxide (ITO) with rubbing-treated polyimide. These results are very encouraging for replacing ITO electrodes with few-layer graphene in LC display applications.     

Ion beam-generated surface ripples: new insight in the underlying mechanism

A new hydrodynamic mechanism is proposed for the ion beam-induced surface patterning on solid surfaces. Unlike the standard mechanisms based on the ion beam impact-generated erosion and mass redistribution at the free surface (proposed by Bradley-Harper and its extended theories), the new mechanism proposes that the incompressible solid flow in amorphous layer leads to the formation of ripple patterns at the amorphous-crystalline (a/c) interface and hence at the free surface. Ion beam-stimulated solid flow inside the amorphous layer probably controls the wavelength, whereas the amount of material transported and re-deposited at a/c interface control the amplitude of ripples.     

Surface Morphology Evolution of GaAs by Low Energy Ion Sputtering

Low energy Ar⁺ ion sputtering, typically below 1,200 eV, of GaAs at normal beam incident angle is investigated. Surface morphology development with respect to varying energy is analyzed and discussed. Dot-like patterns in the nanometer scale are obtained above 600 eV. As the energy approaches upper eV range regular dots have evolved. The energy dependent dot evolution is evaluated based on solutions of the isotropic Kuramoto-Sivashinsky equation. The results are in agreement with the theoretical model which describes a power law dependency of the characteristic wavelength on ion energy in the ion-induced diffusion regime.     

Ion beam ablation of polytetrafluoroethylene

Polytetrafluoroethylene (PTFE) was irradiated with 300 keV Ar⁺ ions to the fluences of 1 × 10¹⁴ to 1 × 10¹⁶ cm⁻²; the PTFE structural changes induced by the ion irradiation were studied by X-ray diffraction and UV–vis and IR spectroscopies. The electrical conductivity of the ion beam modified PTFE was also investigated using the standard technique, and the alterations of the surface polarity were determined by contact angle measurements. The ion irradiation leads to intensive PTFE ablation due to the breaking of the C—C bonds in the polymer molecular chains and due to the production and liberation of the molecular fragments C_xF_y. In contrast to other polymeric materials, the irradiated PTFE carbonizes to a lesser extent and the observed irradiation induced increase of the electrical conductivity is also not significant. In-coming ions cause a reduction of the crystalline phase content in the PTFE samples. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 69: 1257–1261, 1998     

Ion Irradiation of Preceramic Polymer Thin Films

Thin films of two preceramic polymers, namely polycarbosilane (PCS) and a silicone resin (SR350), were deposited on Si substrates. Instead of employing conventional annealing at high temperatures in an inert atmosphere, ion irradiation was used to achieve the polymer-to-ceramic conversion. A detailed investigation of the changes in the composition, chemical structure, and hardness was performed by means of ion beam analysis (Rutherford backscattering spectrometry, nuclear reaction analysis, and elastic recoil detection analysis), FTIR, Raman and nanoindentation, respectively. This processing method yielded amorphous Si-C and Si-O-C coatings possessing high hardness and density. Compared to films heat-treated under vacuum at 1000°C, ion-irradiated ones exhibited a similar hydrogen content, a lower oxygen contamination, and a higher carbon content. Annealing at 1000°C of previously irradiated films resulted in coatings still possessing a high carbon content and a high hardness.     

Adherent Zirconia Films by Reactive Ion Implantation

Conventional methods of forming ceramic coatings on metal substrates, such as CVD or plasma spray, typically retain a sharp interface and may have adhesion problems. In order to produce a completely mixed interface for better adhesion, a method using reactive ion implantation was used which can grow a thick stoichiometric film of an oxide ceramic starting from inside the substrate. Zirconium oxide ceramic films have been produced by this technique using a high-energy zirconium ion beam in an oxygen gas ambient. Compositional data are shown based on Auger electron spectroscopy of the film. Tribological properties of the layer were determined from wear and friction measurements using a pin-on-disk test apparatus. The adhesion was measured both by a scratch technique as well as by thermal shock. Results show an extremely adherent ZrO₂ film with good tribological properties.     

Porous Semiconductor Micropatterns Formed on Focussed Ion Beam Implants

In this work we report a principle that allows one to write visible light emitting silicon patterns of arbitrary shape down to the sub-micrometer scale. We demonstrate that porous Si growth can electrochemically be initiated preferentially at surface defects created in an n-type Si substrate by Si⁺+ ion bombardment. Using a focused ion beam (FIB) as a source of ions, arbitrary defect patterns can be written into a substrate. The growth of light emitting porous silicon is then selectively achieved by an electrochemical treatment which triggers Si dissolution only at these defect sites. The selectivity of the electrochemical dissolution reaction can be attributed to a facilitated Schottky barrier breakdown at the implanted surface defects which leads to the desired pore formation in confined surface areas.     

Ion beam-induced positive imaging of polyimide via two step imidization

The preparation of ion track membranes of thermally stable polyimide films has been performed by ion beam irradiation of partially imidized polyamic acid (PAA) films followed by alkaline etching and final imidization. No discernible positive hole patterns were observed on the irradiated films of partially imidized PAA containing sulfonyl linkages, although sulfonyl group is known to be highly sensitive to ion beams. In contrast, positive hole patterns appeared on the irradiated films of the partially imidized PAA with 68-89% imidization degrees that contains sulfonyl linkages along with a methylene group in the main chain. The most contrasty hole patterns with 0.3 μm diameter were observed on the irradiated PAA films of 89% imidization degree. The irradiated PAA film with the hole patterns was then transformed to the corresponding polyimide film with curing at 350 °C for 1 h. From the structural comparison of the polyimides, the possible mechanism for the hole pattern formation is suggested.     

Focused Ion beam implantation of diamond

The interaction between diamond and a 30 kV Ga⁺ focused ion beam, has been studied. Electron backscattered diffraction identified the critical dose for amorphisation of the diamond surface at 2 × 10¹⁴ Ga⁺/cm². Scanning transmission electron microscopy identified a 35 nm amorphous carbon layer which, at higher doses, can swell up to 31% its original volume and accommodate a significant quantity of gallium. Electron energy loss and energy dispersive X-ray spectroscopy further characterised this layer and identified both excess hydrogen and oxygen contained within a stable amorphous carbon structure.     

Ion Beam Charging of Aerosol Nanoparticles

In our ongoing efforts to achieve the high-efficiency charging of aerosol nanoparticles under low-pressure conditions, our group has recently developed an ion beam aerosol charger (IBAC) that ionizes aerosol nanoparticles using an He⁺ ion beam (Seto et al. 2003 Seto, T., Orii, T., Hirasawa, M., Aya, N. and Shimura, H. 2003. Ion Beam Charging of Silicon Nanoparticles in Helium Background Gas—Design of the Ion Beam Aerosol Charger (IBAC). Rev. Sci. Inst., 74: 3027–3030. [CROSSREF][Crossref] , [Google Scholar]). In earlier studies we have observed both increases and decreases in the currents from the charged particles, depending on the pressure when the polydisperse particles were irradiated by the ion beam. None of our previous studies elucidated the mechanisms of the charging itself, however. In the present paper we evaluate the charging probability of monodisperse aerosol nanoparticles using a low-pressure differential mobility analyzer (LP-DMA) and aerosol electrical condenser (AEC). The particles were negatively charged by the attachment of free electrons generated via the ionization of carrier gas by ion beam irradiation under a pressure of more than 350 Pa. A charging probability of more than 60% was obtained experimentally for the particles of 10–40 nm in mobility diameter under the pressure of 350–650 Pa. The mobility of the particles was almost the same before and after charging in a tandem LP-DMA analysis, with no multiply charged particles observed. The charging probability of nanoparticles was estimated based on the diffusion charging theory. Lastly, experiments were performed to demonstrate the performance of the IBAC in the charging of neutral particles in comparison with that of an α-ray source.     

双离子束溅射非晶SiOxNy薄膜的光致发光研究

采用双离子束溅射法制备了SiOxNy薄膜,用X射线衍射分析(XRD),透射电子显微镜(TEM),X射线光电子能谱(XPS),傅立叶变换红外(FTIR)等对薄膜的结构进行了表征,分析了样品的光致发光(PL)特性。X射线衍射(XRD),透射电子显微镜(TEM)结果表明该薄膜具有非晶结构。XPS测试表明N1s的特征峰位于398eV,对应于N-Si键。在光吸收谱中,与Si-SiO2薄膜相比,SiOxNy的光学带隙得到展宽。在225nm的激光激发下,样品在室温下可发射可见光,峰位位于590nm,与N的缺陷有关。     

Ion beam irradiation effect on gas permeation properties of polyimide films

This study deals with the ion beam irradiation effect on gas permeation properties of polyimide films. 2 MeV α, 500 keV, and 170 keV N⁺ ions were used for modifying the membranes. It was found that there are two different effects according to the implantation dose. In the case of small-dose irradiation, ion implantation causes a raise of permeability both for CH₄ and H₂. When the implantation dose reaches a more important level, the implanted membranes have at the same time high permselectivity for H₂/CH₄ and high permeability for H₂. The relationships between the permeation properties and microstructure of the films are also discussed. © 1995 John Wiley & Sons, Inc.     

离子色谱法测定降水中的阳离子

采用离子色谱法对降水中的阳离子进行测定,实验结果表明,5种阳离子的检出限在0.001～0.003mg· L-1之间,加标回收率在96.0％～104.5％之间,相对标准偏差均小于5％.用离子色谱法测定降水中的阳离子,操作简单、快捷,具有良好的准确度和精密度,灵敏度高,实验结果令人满意.     

离子色谱仪测定水中氟离子的不确定度分析

根据测量不确定度评定与表示理论,对离子色谱仪测定水中氟离子浓度的影响因素进行分析,推导和计算来自重复测量引入的A类不确定度、来自工作曲线的不确定度和来自标准溶液的不确定度。     

离子色谱法测定硫酸根离子的不确定度评定

对离子色谱法测定烟气脱硫吸收液中的硫酸根离子浓度进行了不确定度评定。通过对标准溶液、标准工作曲线拟合、样品稀释和测定过程重复性等影响测定结果的不确定度分量进行分析,计算出测定结果的扩展不确定度,并找出影响该不确定度的主要因素。