Ion Beam Implantation Research Articles

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 × 10 14 Ga +/cm 2. 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.

Genome shuffling of Trichoderma viride for enhanced cellulase production

Genome shuffling is an efficient approach for the rapid engineering of microbial strains with desirable industrial phenotypes. In this study, we used genome shuffling in an attempt to improve the cellulase production of the wild-type strain Trichoderma viride TL-124. The initial mutant populations were generated by ultraviolet (UV) irradiation, low-energy ion beam implantation and atmospheric pressure non-equilibrium discharge plasma (APNEDP). The mutants were subjected to recursive protoplast fusion. The cellulase activities of shuffled strains were assayed after solid-state fermentation using wheat straw, an economical raw material, as substrate. The shuffled strain T. viride F161, which was selected from among about 2,000 shuffled strains after two rounds of genome shuffling, exhibited a total cellulase activity of 4.17 U g-1 dry weight, which was 1.97-fold higher that of wild-type strain T. viride TL-124 (2.12 U g-1 dry weight). Analysis by random amplification of polymorphic DNA revealed genetic differences between the shuffled strains and the wild-type strain.

Tuning Carbon-Based Fuel Cell Catalyst Support Structures via Nitrogen Functionalization. I. Investigation of Structural and Compositional Modification of Highly Oriented Pyrolytic Graphite Model Catalyst Supports as a Function of Nitrogen Implantation Dose

Surface modification and doping of graphitic-carbon catalyst support materials in fuel cell systems, particularly via nitrogen functionalization, has been shown to improve catalyst performance and durability through the optimization of catalyst–support interactions. To ascertain the nature of these interactions, Raman and X-ray photoelectron spectroscopy were used to study the structural and chemical modifications that nitrogen ion beam implantation caused to highly oriented pyrolitic graphite (HOPG) model catalyst support systems. Ion implantation doses explored in this work ranged over 2 orders of magnitude from 9.0 × 1014 to 9.6 × 1016 ions cm–2. Low doses of nitrogen result in a large amount of structural damage with little incorporation of nitrogen. However, it was found that with increasing dosage the incremental increase in structural damage was marginal, while the percentage of nitrogen on the HOPG surface continued to increase significantly until both the level of damage and amount of nitrogen in...

Surface-hardened nanostructured Ti- and Zr-matrix composites for medical and engineering applications

Combined studies have been conducted on the structural-phase state and physical-mechanical and tribological properties of nanostructured titanium and zirconium subjected to ion-beam implantation or microplasma oxidation. Low-temperature ion-beam nitriding of the materials examined is shown to provide a 25–35-fold increase in the wear resistance of their surface layers and a 40% decrease in the friction coefficient for tribological interaction with contact surfaces. Microplasma oxidation of titanium in aqueous solution of phosphoric acid, hydroxylapatite and calcium carbonate powders enables calcium-phosphate coatings with high physical-mechanical properties to be produced. Tribological tests in a dry friction regime and in isotonic solution of sodium chloride have revealed that a nanostructured titanium substrate-calcium phosphate coating biocomposite exhibits a fairly high friction coefficient (0.4–1.0) in tribological interactions with ultrahigh molecular-weight polyethylene or bone tissue. A substantial improvement in the tribotechnical properties of nanostructured titanium and zirconium with modified surface layers makes them very promising materials for medical and engineering applications.

Microbial Lipid Production by Co‐Fermentation with Mortierella alpina Obtained by Ion Beam Implantation

AbstractCo‐fermentation of lignocellulose‐based carbohydrates is a potential approach to improve the economics of microbial lipid production. To obtain an industrial strain that metabolizes glucose and xylose with a higher microbial lipid production, the strain Mortierella alpina was mutated by low‐energy ion beam implantation. After nitrogen ion beam implantation, a mutant strain, M. alpina I502‐8 (MAI502‐8), was obtained. MAI502‐8 was an efficient producer of microbial lipid from glucose and xylose (5:3 wt/wt). Moreover, the co‐fermentation conditions were also optimized. Under optimal conditions, the maximum yield of biomass and microbial lipid reached 27.4 and 10.05 g L–1, respectively, which were 2.38‐fold and 1.84‐fold those in the initial media. Of the mixed sugar, 84.33 % was used up during co‐fermentation.

Mutation breeding of nuclease p1 production in Penicillium citrinum by low-energy ion beam implantation

The mutant strain designated as N409 was obtained with a high yield of nuclease p1. The activity of nuclease p1 was 421 U/mL from the mutant strain N409, which was increased by 86% compared with the control. The fermentation kinetics of nuclease p1 by the mutant strain N409 was studied in a 30 L external airlifting bioreactor. A model was proposed using the logistic equation for microbial growth, the Luedeking-Piret equation for product formation and a Luedeking-Piret-like equation for substrate uptake. The results predicted from the model were in good agreement with the experimental observations.

Strong d–d electron interaction inducing ferromagnetism in Mn-doped LiNbO 3

Mn-doped LiNbO 3 was prepared by ion beam implantation with Mn content of 1 to 5 at.%. The samples were ferromagnetic. The maximum atomic magnetic moment was 5.83 μ B/Mn for the samples with Mn content of 3 at.% in the implanted layer. Structure characterization using X-ray absorption near edge structure determined that the Mn atoms substituted principally the Li atoms in the LiNbO 3 lattice. The magnetic mechanism was understood with the aid of electronic structure calculation using local density approximations plus U method. The calculated results demonstrated that the Mn:LiNbO 3 with Mn atom on the Li site is half-metallic ferromagnetic. The calculated magnetic moment per cell agreed well with the experimental results. Spin splitting of the d-states occurred for both the Mn dopant and the Nb atoms. The doped Mn atom interacts strongly with its neighboring Nb atoms. This strong d–d electron interaction can work at long range through the whole crystalline cell.

Magnesium nitride phase formation by means of ion beam implantation technique

AbstractNitrogen implantation technique (Hardion+) has been applied in order to modify the surface properties of magnesium and Mg-based alloys (AM50, AZ31). Nitrogen ions with an energy of approximately 100keV were used to form the Mg3N2 phase leading to improved surface properties. The samples were investigated using various characterization methods. Mechanical properties have been tested by means of nanoindention, the electrochemical behavior was measured by potentiodynamic polarization and impedance spectroscopy, phase formation by using grazing incidence Xray diffraction, the chemical state was determined by means of Xray induced photoelectron spectroscopy (XPS) and depth profiling by using secondary ions mass spectroscopy (SIMS). Additionally, the results were compared to calculated depth profiles using SRIM2008. The correlation of the results shows the nitride formation behavior to a depth of about 600nm.

Improved thermostable α-amylase activity of Bacillus amyloliquefaciens by low-energy ion implantation

Thermostable α-amylase is of great importance in the starch fermentation industry; it is extensively used in the manufacture of beverages, baby foods, medicines, and pharmaceuticals. Bacillus amyloliquefaciens produces thermostable α-amylase; however, production of thermostable α-amylase is limited. Ion-beam implantation is an effective method for mutation breeding in microbes. We conducted ion-beam implantation experiments using two different ions, Ar(+) and N(+), to determine the survival rate of and dose effect on a high α-amylase activity strain of B. amyloliquefaciens that had been isolated from soil samples. N(+) implantation resulted in a higher survival rate than Ar(+) implantation. The optimum implantation dose was 2.08 × 10(15) ions/cm(2). Under this implantation condition, we obtained a thermally and genetically stable mutant α-amylase strain (RL-1) with high enzyme activity for degrading α-amylase. Compared to the parental strain (RL), the RL-1 strain had a 57.1% increase in α-amylase activity. We conclude that ion implantation in B. amyloliquefaciens can produce strains with increased production of thermostable α-amylase.

Manipulation of amorphous Ge2Sb2Te5 nano-structures in isolated and crystalline environment.

ABSTRACTWe have investigated the stability of nano-amorphous region of Ge2Sb2Te5 (GST), fabricated by Electron Beam Lithography (EBL), dry etching, and ion implantation. Nano-structures, less than 100 nm in diameter and 20 nm thick, were either embedded in a crystalline environment or just isolated. We have observed nano-structure crystallization by in situ Transmission Electron Microscopy (TEM) in the 75°C-150°C temperature range. Re-crystallization of amorphous dots embedded in a crystalline region (either in the cubic or hexagonal phase) occurs by the movement of the interface at relatively low temperature (about 90°C). Instead, in the isolated structures the transition occurs at about 145°C by nucleation and growth. These results might be of relevance for the data retention of sub-50nm devices. Indeed, the more stable amorphous phase in self-standing regions indicates the better retention properties of isolated cells with respect to the traditional mushroom cell configuration.

Strain improvement for enhanced production of cellulase in Trichoderma viride

The filamentous fungi Trichoderma species produce extracellular cellulase. The current study was carried out to obtain an industrial strain with hyperproduction of cellulase. The wild-type strain, Trichoderma viride TL-124, was subjected to successive mutagenic treatments with UV irradiation, low-energy ion beam implantation, atmospheric pressure non-equilibrium discharge plasma (APNEDP), and N-methyl-N'-nitro-N-nitrosoguanidine to generate about 3000 mutants. Among these mutants, T. viride N879 strain exhibited the greatest relevant activity: 2.38-fold filter paper activity and 2.61-fold carboxymethyl cellulase, 2.18-fold beta-glucosidase, and 2.27-fold cellobiohydrolase activities, compared with the respective wild-type activities, under solid-state fermentation using the inexpensive raw material wheat straw as a substrate. This work represents the first application of APNEDP in eukaryotic microorganisms.

Focused ion beam implantation of Ga in InP studied by SIMS and dynamic computer simulations

AbstractFocused ion beam implantation of 30 keV Ga+ ions in single‐crystalline InP was investigated by SIMS, using Cs+ primary ions for sputtering. Nine different implantation fluences ranging from 1 × 1013 to 1 × 1017 Ga+ ions/cm2 were used, with implanted areas of 50 × 50 µm2. The Ga concentration distributions of these implants were determined by SIMS depth profiling. Such 30 keV Ga implantations were also simulated by a dynamic Monte Carlo simulation code that takes into account the gradual change of the near‐surface composition due to the Ga incorporation. In both approaches, an essentially linear increase of the Ga content with fluence is found up to ∼1 × 1016 cm−2; for higher fluences, the Ga peak concentration approaches a saturation level which is reached at about (0.5–1) × 1017 cm−2 and amounts to ∼10%. The measured and simulated concentrations of the Ga distributions are in good agreement. The most probable range of the Ga+ ions in InP obtained from the SIMS experiments is ∼23 nm and matches closely with the value from the simulations. Copyright © 2010 John Wiley & Sons, Ltd.

Formation of Nano Diamonds in Surface Layer of Materials during Short Pulse Ion Beam Implantation

Formation of Nano Diamonds in Surface Layer of Materials during Short Pulse Ion Beam Implantation

Tuning the electrical performance of Ge nanowire MOSFETs by focused ion beamimplantation

In this work, we demonstrate an approach to tune the electrical behavior of ourΩ-gated germanium-nanowire (Ge-NW) MOSFETs by focused ion beam (FIB) implantation.For the MOSFETs, 35 nm thick Ge-NWs are covered by atomic layer deposition (ALD) of a high-κ gate dielectric.With the Ω-shaped metal gate acting as implantation mask, highly doped source/drain (S/D) contactsare formed in a self-aligned process by FIB implantation. Notably, without any dopantactivation by annealing, the devices exhibit more than three orders of magnitude higherION currents, animproved ION/IOFF ratio, a higher mobility and a reduced subthreshold slope of140 mV/decade compared to identical Ge-NW MOSFETs without FIB implantation.

Breeding of high lipid producing strain of Geotrichum robustum by ion beam implantation

To obtain an industrial strain with high lipid yield, the wild strain G0 of Geotrichum robustum was mutated by means of nitrogen ions implantation. Mutagenic effects of strain G0 by low energy N+ ion implantation were studied. The experimental results indicated that the survival rate curve took a “saddle” shape, and the positive mutation rate was increased to 22.00% at the dose of nitrogen ions 2.0 x 1015 ions/cm2 when the survival rate was 28.60%. By repeated screening, a high lipid producing strain G9 was obtained. The biomass, lipid content and lipid yield of the mutant can reach 40.25 g/L, 71.14% and 28.63 g/L after cultured in a 5L fermenter for 8 days, increasing by 52.81%, 68.82% and 157.93% to those of wild strain, respectively. Analysis results on fatty acids composition and relative content by gas chromatography and mass spectrometry showed that the lipid in strain G9 was mainly composed of 16-carbon and 18-carbon fatty acids, including 37.360% oleic acid, 23.631% palmitic acid, 4.458% linoleic acid and 26.465% stearic acid. Such compositional features were quite similar to plant oil. Geotrichum robustum strain G9 may be an ideal high lipid producing strain for biodiesel production

Strain improvement and metabolic flux modeling of wild-type and mutant Alcaligenes sp. NX-3 for synthesis of exopolysaccharide welan gum

Low-energy nitrogen ion beam implantation technique was used for the strain improvement of Alcaligenes sp. NX-3 for the production of exopolysaccharide welan gum. A high welan gum producing mutant, Alcaligenes sp. NX-3-1, was obtained through 20 keV N+ ion beam irradiation. Starting at a concentration of 50 g/L of glucose, mutant NX-3-1 produced 25.0 g/L of welan gum after 66 h of cultivation in a 7.5 L bioreactor, which was 34.4% higher than that produced by the wild-type strain. The results of metabolic flux analysis showed that the glucose-6-phosphate and acetyl coenzyme A nodes were the principle and flexible nodes, respectively. At the glucose-6-phosphate node, the fraction of carbon measured from glucose-6-phosphate to glucose-1-phosphate was enhanced after mutagenesis, which indicated that more flux was used to synthesize welan gum in the mutant. By analyzing the activities of related enzymes in the biosynthetic pathway of sugar nucleotides essential for welan gum production, we found that the specific activities of phosphoglucomutase, UDP-glucose pyrophosphorylase, UDP-glucose dehydrogenase, and dTDP-glucose pyrophosphorylase in the mutant strain were higher than those in the wild-type strain. These improvements in enzyme activities could be due to the affected of ion beam implantation.

Modulation of viability of live cells by focused ion‐beam exposure

Introduction of membrane-impermeant substances into living cells is the key method to understand contemporary cellular processes by investigating cellular responses and phenotypes. Here, we performed gold ion beam exposure into live cells by using the focused ion beam implantation method, which was originally developed to precisely control semiconductor device performances. We evaluated the viability of the gold-irradiated cells by measuring the concentration of adenosine triphosphate (ATP), which is an intracellular energy source produced in the mitochondrial membrane. The viability of the irradiated cells was found to be 20% higher than that of the unirradiated control cells. The atoms might promote the energy generating processes within the mitochondrion. Our results suggest that the viability of living cells can be modulated by accurately controlling the dopant atom numbers. Our technique may be considered as a potential tool in life and medical sciences to quantitatively elucidate the dose-dependent effects of dopants.

ChemInform Abstract: The Corrosion Behavior of Mo-Al, Cr-Al and Cr-Mo-Al Surface Alloys Produced by Ion Beam Mixing and Ion Implantation

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Study of erbium-doped silicon nanocrystals in silica

Er-doped SiO2 and Er-doped Si-NCs embedded in a SiO2 matrix were produced by Er and/or Si ion beam implantation of a Si (100) substrate. The composition and distribution of implanted Er varies in samples either with or without Si implants. HAADF and EELS detail in samples with Si implants, the Si and Er distribution is identical, and within a band of ~110 nm width at ~75 nm below the SiO2 surface. Intense PL emission at 1.54 μm confirms formation of ErSi2, for the majority of aggregates, is unlikely. The present investigation details most Si-NCs are surrounded by Er2O3, or possess this phase within.

Zone-plate focusing of Bose–Einstein condensates for atom optics and erasable high-speed lithography of quantum electronic components

We show that Fresnel zone plates (ZPs), fabricated in a solid surface, can sharply focus atomic Bose–Einstein condensates that quantum reflect from the surface or pass through the etched holes. The focusing process compresses the condensate by orders of magnitude despite inter-atomic repulsion. Crucially, the focusing dynamics are insensitive to quantum fluctuations of the atom cloud and largely preserve the condensates' coherence, suggesting applications in passive atom-optical elements, for example ZP lenses that focus atomic matter waves and light at the same point to strengthen their interaction. We explore transmission ZP focusing of alkali atoms as a route to erasable and scalable lithography of quantum electronic components in two-dimensional electron gases (2DEGs) embedded in semiconductor nanostructures. To do this, we calculate the density profile of a 2DEG immediately below a patch of alkali atoms deposited on the surface of the nanostructure by zone-plate focusing. Our results reveal that surface-induced polarization of only a few thousand adsorbed atoms can locally deplete the electron gas. We show that, as a result, the focused deposition of alkali atoms by existing ZPs can create quantum electronic components on the 50 nm scale, comparable to that attainable by ion beam implantation but with minimal damage to either the nanostructure or electron gas.