Ion Beam Implantation Research Articles

Nitrogen removal from eutrophic water by floating-bed-grown water spinach ( Ipomoea aquatica Forsk.) with ion implantation

The aim of this study was to investigate the use of water spinach ( Ipomoea aquatica Forsk.) with N + ion-beam implantation for removal of nutrient species from eutrophic water. The mutated water spinach was grown on floating beds, and growth chambers were used to examine the growth of three cultivars of water spinach with ion implantation for 14 days in simulated eutrophic water at both high and low nitrogen levels. The specific weight growth rates of three cultivars of water spinach with ion implantation were significantly higher than the control, and their NO 3-N and NH 4-N removal efficiencies were also greater than those of the control. Furthermore, compared with the control, the nitrogen contents in the plant biomass with ion implantation were higher as well.

Optics calculations and beam line design for the JANNuS facility in Orsay

JANNuS (Joint Accelerators for Nano-Science and Nuclear Simulation) will be a unique user facility in Europe dedicated to material modification by ion beam implantation and irradiation. The main originality of the project is that it will be possible to perform implantation and irradiation with simultaneous multiple ions beams and in situ characterization by transmission electron microscopy (TEM) observation or ion beam analysis. This facility will be composed of two experimental platforms located in two sites: the CEA-SRMP in Saclay and the CNRS-CSNSM in Orsay. This paper will focus on the design of two new transport beam lines for the Orsay site.One of the most challenging parts of the JANNuS project (Orsay site) is to design two new beam lines in order to inject, into a 200kV TEM, two different ion beams (low and medium energy) coming from two existing pieces of equipment: a 2MV Tandem accelerator and a 190kV ion implanter.For these new beam lines, first order beam calculations have been done using transfer matrix formalism. A genetic algorithm has been written and adapted to perform the optimization of the beam line parameters. Then, using the SIMION code, field maps of the electrostatic elements (quadrupoles, spherical sectors) have been calculated and ion trajectories have been simulated. We studied specifically the optical aberrations induced by the electrostatic spherical deflectors. Finally, the results of the first order calculations and the field map simulations show a good agreement.

Focused Ion Beam Micro- and Nanoengineering

AbstractThis article discusses applications of focused ion beam micro- and nanofabrication. Emphasis is placed on illustrating the versatility of focused ion beam and dual-platform systems and how they complement conventional processing techniques. The article is divided into four parts: maskless milling, ion beam lithography, ion implantation, and techniques such as in situ micromanipulation.

Investigations on a Co–Dy liquid alloy ion source

We have investigated the emission characteristics of a Co–Dy liquid alloy ion source intended for focused ion beam implantation of cobalt and dysprosium ions. An alloy composition of Co2Dy was selected in order to have a relatively low melting temperature, sufficient cobalt concentration for ion implantation purposes and low corrosion effects of the alloy and emitter tungsten wires. We have measured the melting behaviour of the alloy, the emission current stability, the current–voltage characteristics and the mass and energy spectra as a function of source current using a time-of-flight spectrometer. The ion source exhibits a good performance even after storage for several weeks in dry air. The mass spectra show a high intensity of doubly charged dysprosium ions and singly and doubly charged cobalt ions. The Co–Dy source works in a stable way for at least several days.

Studies on Mutation Breeding of High-Yielding Xylanase Strains by Low-Energy Ion Beam Implantation

As a new mutagenetic method, low-energy ion implantation has beenused widely in many research areas in recent years. In order toobtain some industrial strains with high xylanase yield, the wildtype strain Aspergillus niger A3 was mutated by means of nitrogenions implantation (10 keV, 2.6 × 1014 ∼ 1.56× 1015 ions/cm2) and a mutant N212 was isolatedsubsequently. However, it was found that the initial screening meansof the high-yielding xylanase strains such as transparent halos wasunfit for first screening. Compared with that of the wild typestrain, xylanase production of the mutant N212 was increased from320 IU/ml to 610 IU/ml, and the optimum fermentation temperature wasincreased from 28 oC to 30 oC.

Nanostructures by ion beams

Ion beam techniques, including conventional broad beam ion implantation, ion beam synthesis and ion irradiation of thin layers, as well as local ion implantation with fine-focused ion beams have been applied in different fields of micro- and nanotechnology. The ion beam synthesis of nanoparticles in high-dose ion-implanted solids is explained as phase separation of nanostructures from a super-saturated solid state through precipitation and Ostwald ripening during subsequent thermal treatment of the ion-implanted samples. A special topic will be addressed to self-organization processes of nanoparticles during ion irradiation of flat and curved solid-state interfaces. As an example of silicon nanocrystal application, the fabrication of silicon nanocrystal non-volatile memories will be described. Finally, the fabrication possibilities of nanostructures, such as nanowires and chains of nanoparticles (e.g. CoSi2), by ion beam synthesis using a focused Co+ ion beam will be demonstrated and possible applications will be mentioned.

Excimer laser absorption by metallic nano-particles embedded in silica

Metallic nano-particles embedded in silicon dioxide have optical properties that are of interest for their possible technological applications in the near future. These properties have been found to depend on their size and shape as well as on their surroundings. In this paper we investigate the effect of 308 nm excimer laser irradiation on silver and gold nano-particles embedded in high quality synthetic silica produced by 2 MeV ion-beam implantation followed by a thermal annealing. Laser irradiation induces nano-particle dissolution and diffusion to the surface and eventually loss of the metal accompanied by ablation of the surface. We show by numerical solution of the heat conduction equation that the process can be understood by considering that the nano-particles are responsible for the laser absorption and that nano-particles dissolution, and subsequent diffusion to the surface, take place when the nano-particles melting temperature is reached.

Information obtainable from ion beam luminescence

During ion beam implantation there is associated luminescence from insulators which contains information on the crystallinity of the host lattice, the structural perfection of the surface region, impurity content, intrinsic defects and variations in phase, nanoparticle inclusions and lattice stability. Hence, ion beam luminescence can provide both an immediate diagnostic probe of the changes which occur during implantation and an independent means of analysing defects in the near surface region. The technique is similar to cathodoluminescence but has advantages that it probes a greater depth of material with a more controllable rate of energy deposition in the layer. By the use of different ions and molecular beams one can explore dose rate dependence effects and distinguish between alternative defect models. In the diagnostic role there are further benefits from varying the target temperature and from using beam modulation to probe differences in lifetime of the excited luminescence sites. Ion beam signals are less sensitive to surface contaminants than cathodoluminescence and by changing the ion beam energy one may progressively interrogate the surface structure over depths of tens of microns. Examples from each of the various situations will be presented and these will underline the fact that the technique is extremely powerful. Since it is under exploited suggestions for new experiments are considered.

Enhancement of Gongronella sp. JG Chitosanase Production by Ion Beam Implantation

Gongronella sp. JG was a fungal strain which expressed extracellularchitosanase of about 800 U/L during its growth in production medium.To improve its enzyme production, low energy N+ implantation wasemployed to mutate spores of JG. The implantation condition wasoptimized and the parameters of 15 keV and 60 × 2.6× 1013 ions/cm2 were selected for further breedingexperiments. A mutant designated as SG was obtained. It showedincreased chitosanase production (1800 U/L) and shortenedcultivation period (from 72 h to 60 h). Five-generation cultivationof SG indicated that its chitosanase production was stable at about1800 U/L.

Sensing thermal conductivity and structural effects at the nanoscale by scanning thermal microscopy (SThM)

We introduce the theoretical description of 3ω signal from the Wollaston probe of a scanning thermal microscope (SThM) in terms of an equivalent low-pass filter. We performed thermal conductivity k measurements with lateral resolution of about 100 nm. The first application concerns NiTi shape memory alloys microstructured by focused ion beam implantation. Local martensite to austenite structural phase transition has been identified upon heating the sample from room temperature to 100°C The 3w signal changes were -1.95% in amplitude and 0.6° in phase, corresponding to thermal conductivity k increase of 3.5%. The second application consists of static measurement of local k on points situated on flat faces of bare diamond crystallites 300 μm in diameter, and on crystallites coated with Cr, Cu and Cu/Cr layers with thickness in the range 0.5-30 μm. The high k advantage of bare crystallites is lost upon coating the particles, but the thermal barrier depends also on the specific configuration when the particles are in contact to one another in materials obtained from such powders.

Optical waveguides in laser crystals

This article reviews the recent research on different types of planar and channel crystalline optical waveguides, fabrication methods such as liquid phase epitaxy, pulsed laser deposition, thermal bonding, reactive ion or ion beam etching, wet chemical etching, ion in-diffusion, proton exchange, ion beam implantation, and femtosecond laser writing, as well as waveguide laser operation of rare-earth and transition-metal ions in oxide crystalline materials such as Al 2O 3, Y 3Al 5O 12, YAlO 3, KY(WO 4) 2, and LiNbO 3. To cite this article: M. Pollnau, Y.E. Romanyuk, C. R. Physique 8 (2007).

Mutation breeding of chitosanase-producing strain Bacillus sp. S65 by low-energy ion implantation

In order to obtain an industrial strain with higher chitosanase yield, the wild strain Bacillus sp. S65 cells were mutated by a novel mutagen, nitrogen ion beam, with energy of 15 keV and dose ranging from 2.6 x 10(14 )to 5.2 x 10(15) ions/cm(2). One mutant, s65F5 with high yield of chitosanase was isolated. Results showed that the production of chitosanase of s65F5 was dramatically increased from 4.1 U/ml in s65 to 25 U/ml by ion beam implantation, while the fermentation time was shortened from 72 to 56 h, both of which greatly increased efficiency and reduced the cost of industrial production. Besides, the mutagenic effects of low-energy ion beam on survival rate showed characteristic down-up-down pattern, which was different from the traditional mutagens such as UV and gamma-ray and the possible mutation mechanism was discussed.

Oxygen Plasma Ion Implantation of Biomedical Titanium Alloy

Titanium alloys have attracted more attention as biomaterials. Plasma ion implantation is utilized in this paper to improve the bioactivity, wear resistance, and corrosion resistance of Ti6Al4V alloy. As an effective surface-modification technique, plasma ion implantation eliminates the limitation of light of sight compared to conventional beam ion implantation. The plasma is excited by an RF power ranging from 200 to 400 W with sample bias of 20 kV. The results show the improvement in hardness, corrosion resistance, and tribological properties. Longer treatment time or higher RF power leads to a higher wear resistance. The friction coefficient rapidly increases at 500 s with the sample treated with the RF power of 400 W, while it changes abruptly at 1500 s with the sample processed with the RF power of 600 W. After the treatment, the corrosion resistance is considerably improved, which demonstrate that the potential of the samples shift positively while the corrosion current decreases substantially. The corrosion current may decrease by a factor of six compared to that of the control sample. The precipitates containing phosphorous and calcium appear, indicating a better activity while nothing grows on the untreated sample

Sticking behavior of the dopants Si, C, and Be upon re-evaporation of individually doped GaAs(1 0 0)

The behavior of the dopants Si, C, and Be upon re-evaporation of correspondingly doped GaAs was studied. The samples were prepared on semi-insulating GaAs (1 0 0) by using molecular beam epitaxy (MBE) technique and focused ion beam (FIB) implantation, and were studied by Hall measurement and Secondary Ion Mass Spectroscopy. It was found that a significant fraction of dopant atoms (Si, C, or Be) was not desorbed when the doped material was re-evaporated. It was also found that after re-evaporation of the doped layer, Si- and Be-doped samples still were electrically conducting, but the C-doped samples were not. It was also found that Si-doped sample became nonconducting if the re-evaporation thickness was much larger than that of the doped layer. The comparison of Hall and Secondary Ion Mass Spectroscopy data shows that the electrical activation for all the three dopant species decreases after re-evaporation. The sticking behavior of dopants Si, C, and Be upon re-evaporation of doped GaAs is proposed to be attributed to the lower volatility of elements Si, C, and Be compared to Ga and As.

A Mutant of Bacillus Subtilis with High-Producing Surfactin by Ion Beam Implantation

In order to generate a mutant of Bacillus subtilis with enhanced surface activity through low energy nitrogen ion beam implantation, the effects of energy and dose of ions implanted were studied. The morphological changes in the bacteria were observed by scanning electron microscope (SEM). The optimum condition of ions implantation, 20 keV of energy and 2.6×1015N+/cm2 in dose, was determined. A mutant, B.s-E-8 was obtained, whose surface activity of 50-fold and 100-fold diluted cell-free Landy medium was as 5.6-fold and 17.4-fold as the wild strain. The microbial growth and biosurfactant production of both the mutant and the wild strain were compared. After purified by ultrafiltration and SOURCE 15PHE, the biosurfactant was determined to be a complex of surfactin family through analysis of electrospray ionization mass spectrum (ESI/MS) and there was an interesting finding that after the ion beam implantation the intensities of the components were different from the wild type strain.

Fabrication of submicrometer patterned two-dimensional electron gases by overgrowth of focused ion beam doped AlxGa1−xAs

Laterally patterned two-dimensional electron gases have been fabricated by overgrowth of locally implantation doped Al0.33Ga0.67As barriers. The heterostructures were grown by molecular beam epitaxy and the local doping was performed by focused ion beam implantation. Submicrometer patterning capability was found when testing the insulation behavior of doping interruptions between two conducting rectangles. For a narrow conducting wire, an electronic width of approximately 350nm was realized. The experiments show that the thermal processing necessary to remove the implantation damage might hamper the lateral resolution and has to be optimized.

Tuning Magnetic Domain Structure in Nanoscale La0.7Sr0.3MnO3 Islands

The realization of spin-based devices requires high density, ordered arrays of magnetic materials with a high degree of spin polarization at surfaces. We have synthesized, for the first time, highly spin polarized complex magnetic oxide nanostructures embedded in a paramagnetic matrix by electron beam lithography and ion implantation. Imaging the magnetic domains with X-ray photoemission electron microscopy and magnetic force microscopy reveals a delicate balance between magnetocrystalline, magnetoelastic, and magnetostatic energies that can be tuned by the choice of SrTiO3 substrate orientation, film thickness, island size, and island shape.

Fabrication of genuine single-quantum-dot light-emitting diodes

We present a simple approach for the fabrication of genuine single quantum-dot light-emitting diodes. A submicron wide bottom contact stripe is formed by focused ion beam implantation doping into a GaAs buffer layer. Successive overgrowth with a thin intrinsic layer incorporating self-assembled InAs quantum dots, followed by a top contact layer of complementary doping type and standard photolithographic processing, allows for electrical cross sections in the sub-μm2 range. In devices with sufficiently low dot densities, only one single dot is expected to be electrically addressed. Both the observed current versus voltage characteristics and the evolution of the electroluminescence spectra as a function of applied voltage clearly demonstrate that this goal has been achieved.

Bioeffects of Low Energy Ion-Beam Implantation and Vacuum Treatment on M$_1$ Arabidopsis Thaliana

Vacuum treatment and ion-beam bombardment are two major processes in the low energy ion-beam implantation. To accurately study the contributions of these two major factors to the bioeffects separately, the M1 generation variation of Arabidopsis thaliana with ion-beam implantation and vacuum treatment were compared through a series of key plant development parameters including morphological observation, biochemical assay and RAPD (random amplified polymorphic DNA) analysis. The results showed that ion-beam implantation had obvious effect on almost all of these parameters, and the vacuum treatment had some impacts on several morphological parameters such as the bolting time and the length of the primary stem. Taking the results together, the indication is that vacuum treatment has some slight contributions to the bioeffects of ion-beam implantation while ion-beam bombardment itself is the major creator of the bioeffects.

Accumulation of 2-Keto-L-Gulonate at 33°C by a Thermotolerant Gluconobacter Oxydans Mutant Obtained by Ion Beam Implantation

To obtain thermotolerant mutants of G. oxydans, which can enhance the transformation rate of L-sorbose to 2-Keto-L-gulonate (2-KLG) at 33oC in a two-step process of vitamin C manufacture, ion beam was used as a mutation source. Gluconobacter oxydans G0 and Bacillus megaterium B0 were used in this study. The original strain Gluconobacter oxydans G0 was mutated by the heavy ion implantation facility at the Institute of Plasma Physics, Chinese Academy of Sciences. Several mutants including Gluconobacter oxydans GI13 were isolated and cocultured with Bacillus megaterium B0 at 33oC in shaking flasks. The average transformation rate of the new mixed strain GI13-B0 in per gram-molecule reached 94.4% after seven passages in shaking flasks, which was increased by 7% when compared with the original mixed strain G0-B0 (Gluconobacter oxydans G0 and Bacillus megaterium B0). Moreover, the transformation rate of I13B0 was stable at 94% at temperatures ranging from 25oC to 33oC, which would be of much value in reducing energy consumption in the manufacture of L-ascorbic acid, especially in the season of summer. To clarify some mechanism of the mutation, the specific activities of L-sorbose dehydrogenase in both G0 and GI13 were estimated.