Effect Of Ion Beam Bombardment Research Articles

Noble gas ion beam bombardment effects on H-, graphite -, Na-, Fe- and Zn-doped MgO thin films in plasma-related discharge devices

Doping with various elements to the MgO film is better suited for increasing secondary electron emission coefficient This allows the evolution of the luminous efficacy and the lifespan of the plasma-related devices. The resistance against ion sputtering is another critical issue for the prolongation of the lifespan. This research focuses on the effect of H-, Graphite -, Na-, Fe-and Zn -ion-doping on sputtering yields and numbers of vacancies created in MgO as a function of ion energy and incident angle. Our simulation have shown that the MgO doped exhibit better sputtering resistance and lower numbers of vacancies.

The Effect of Ion-Beam Bombardment on Solution-Processed Nickel Oxide Films Used for Liquid Crystal Alignment

We induced a homogeneous liquid crystal (LC) alignment state on ion-beam (IB)-irradiated NiO films fabricated via solution-processing. A topographical analysis was performed using field emission-scanning electron microscopy of the films after various annealing temperatures. After IB irradiation, the surface of the NiO films was rough irrespective of annealing temperature. IB-irradiated NiO films exhibited slightly reduced transparency in the visible region compared to as-deposited NiO film. Moreover, the IB-irradiated NiO films fabricated at the lowest annealing temperature of 100°C exhibited uniform homogeneous LC alignment caused by microgroove-like topographic modification and chemical modification of the NiO surface by the IB irradiation. The pretilt angle of the LC molecules on IB-irradiated NiO film annealed at 100, 200, 300, and 400°C were on average 0.02 0.05, 0.43, and 0.05o, respectively, making IB-irradiated NiO film eminently suitable for LC alignment.

Regulating interface adhesion and enhancing thermal conductivity of diamond/copper composites by ion beam bombardment and following surface metallization pretreatment

A new pretreatment process, namely, Ar+ ion beam bombardment and following deposition of a tungsten coating layer on diamond particles for fabricating diamond/copper composites is proposed in this paper. The composites are fabricated by infiltration method, and exhibited excellent thermal properties. Composition of the tungsten coated diamond particles is characterized by the Micro-XRD to investigate the effect of ion beam bombardment on the selectivity of interfacial reaction between the diamond planes and the coating layer. Scanning electron microscopy (SEM) is used to investigate the effect of the ion beam bombardment on interface structure and composition of the composites. A good interfacial adhesion without micro-gaps or cracks in the interfacial region is obtained. In addition to that, the phenomenon of selective interfacial reaction in the composite is no longer taking place, and the metal matrix uniformly adheres to all diamond planes. Therefore, the further enhancing thermal conductivity of the composites reach up to 896 W m−1 K−1, and coefficient of thermal expansion is only 5.9 × 10−6 K−1. The excellent performance can be attributed to the regulated interfacial adhesion and the optimized effective interfacial thermal conductance.

Controlling cell morphology on ion beam textured polymeric surfaces

Objectives: Nano and micro sized textures on surfaces are generally useful biomaterials. Although the importance of roughness degree has been reported for cell morphology, texture morphology can be more determining for cell adhesion and proliferation. Biodegradable polymers are extensively used as scaffolds as well as implant materials in the human body. The aim of this study was to investigate the effect of ion beam bombardment on cell morphology. Methods: Gold and carbon ion implantation was made on biodegradable polymers polyglycolic acid, polycaprolactone and polylactic-co-glycolic-acid. Roughness data were obtained from atomic force microscopy. After surface modification with ion beam, B35 neural cells were evaluated on surfaces for cell compatibility. Morphology and cell surface interaction were analyzed with scanning electron microscopy. Results: We observed improved cell adhesion after ion beam surface modification. Cell adhesion was greater on gold implanted surfaces compared to the carbon implanted. Neural cells attached to lamellar wrinkles, spread by taking the shape of the pattern and exhibited high aspect ratios and axon extension. In contrast, cells that attached on the untreated surfaces remained rounded with low spreading. Conclusion: The findings of this study are important for development of ion beam modified cell cultures and scaffold systems to understand texture-based cell adhesion mechanisms. Keywords: cell culture; ion implantation; polylactic-co-glycolic acid; surface treatment; topography; wettability

Effect of ion-beam bombardment on microstructural and magnetic properties of Ni80Fe20/α-Fe2O3 thin films

Ion-beam bombardment has been established as an effective way to tune the microstructure and thus modify the magnetic anisotropy of thin film materials, leading to certain remarkable magnetic properties. In this work, we investigated a Ni80Fe20/α-Fe2O3 bilayer deposited with a dual ion-beam deposition technique. Low-energy argon ion-beam bombardment during the α-Fe2O3 deposition led to a decline of crystallinity and interfacial roughness of the bilayer, whereas the grain size distribution remained essentially unchanged. At low temperature, the coercivity exhibited a pronounced decrease after the bombardment, indicating that the effective uniaxial anisotropy in the ferromagnetic layer was dramatically reduced. Such reduction in uniaxial anisotropy was likely attributed to the irreversible transition in the α-Fe2O3 grains caused by the ion-beam bombardment, which subsequently modified the anisotropy in the Ni80Fe20 layer. The bombarded bilayer also exhibited a larger ΔMFC–ZFC compared to the un-bombarded bilayer, which indicated a stronger exchange coupling between the ferromagnetic layer and the antiferromagnetic layer.

Influence of ion-beam bombardment on the physical properties of 100Cr6 steel

The effect of ion-beam bombardment with low energy Xe ions on the physical properties of 100Cr6 steel is reported. The modified region induced by the relative low energy ions (<1 keV) extends orders of magnitude deeper than the stopping length of the impacting ions. The energy dependence of the in-depth stress and the pattern formation is also verified. The formation of peculiar patterns on the treated surface is discussed by evoking the current model of surface instability produced by preferential sputtering and surface diffusion in metals.

Effect of N&lt;sub&gt;2&lt;/sub&gt; Ion Bombardment on Optical and Mechanical Properties of Ultra-High Molecular Weight Polyethylene (UHMWPE)

The effect of ion beam bombardment on the optical and mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) was investigated. UHMWPE polymer samples were bombarded with 150 keV N2ions under vacuum at room temperature to high fluences ranging from 1x1016to 2x1017ions cm-2. The untreated as well as treated samples were investigated by ultraviolet-visible (UV-Vis) spectrophotometer and Vickers micro-hardness techniques. The direct and indirect optical band gap decreased from 2.9 and 1.65 eV for pristine sample to 1.7 and 1 eV for those bombarded with N2ion beam at the highest fluence, respectively. With increasing ion fluence, an increase in the number of carbon atoms per conjugation length, N and number of carbon atoms per cluster, M in a formed cluster were observed. A significant improvement in surface hardness was obtained by increasing the ion fluence.

Modulating the Magneto-Crystalline Anisotropy and the Exchange Bias Field in CoFe/(Co,Fe)O Bilayers Using Ion-Beam Bombardment and Single Crystalline Substrates

We report the effects of ion-beam bombardment on the room temperature and low temperature magnetic properties of ferromagnetic CoFe/antiferromagnetic (Co,Fe)O thin film bilayers. The films were deposited onto amorphous SiO2 and single crystalline MgO (110)/(100) substrates. Magnetometry showed that ion-beam bombardment was capable of modifying the coercivity and loop shape for the thin film system at room temperature, corresponding to alteration of the effective magneto-crystalline anisotropy field. After field cooling to 50 K, a shifted hysteresis loop was seen for those films containing a proportion of the antiferromagnetic rock-salt (Co,Fe)O phase, with an exchange bias magnitude that depended on the ion-beam bombardment conditions. Our results indicate that matching the substrate with appropriate ion-bombardment conditions provides a promising way to engineer selectively two important types of magnetic anisotropy in ferromagnetic/antiferromagnetic bilayers: magneto-crystalline and exchange bias.

Ion beam modification of surface properties of CR-39

The effects of ion-beam bombardment on the physical and chemical properties of poly(allyl diglycol carbonate) (CR-39) polymer have been investigated. CR-39 samples were bombarded with 320 keV Ar and 130 keV He ions at fluences ranging from 1 × 1013 to 2 × 1016 ions/cm2. The nature and extent of radiation damage induced were studied by UV–VIS spectrometry, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, as well as Vickers' hardness measurements. In addition, the effect of ion fluence on the wetting properties of ion-beam bombarded CR-39 polymer was determined by measuring the contact angle for distilled water. UV–VIS spectra of bombarded samples reveal that the optical band gap decreases with increasing ion fluence for both Ar and He ions. In the FTIR spectra, changes in the intensity of the bands on irradiation relative to pristine samples occurred with the appearance of new bands. XRD analyses showed that the degree of ordering of the CR-39 polymer is dependent on the ion fluence. Changes of surface layer composition and an increase in the number of carbonaceous clusters produced important change in the energy gap and the surface wettability. The surface hardness increased from 10.54 MPa for pristine samples to 28.98 and 23.35 MPa for samples bombarded with Ar and He ions at the highest fluence, respectively.

Effect of ion beam bombardment on the properties of Ni films deposited on polyimide by ion beam assisted deposition

Abstract Highly textured Ni films were deposited on pristine and Ar + ion pre-treated polyimide (PI) by ion beam assisted deposition (IBAD). Effect of Ar + ion bombardment on the surface roughness of PI and the properties of Ni thin films deposited on pristine and pre-treated PI was investigated. The results showed that the structure, residual stress and temperature coefficient of resistivity (TCR) of the films were significantly sensitive to the energy and the ion flux of concurrent Ar + ion bombardment. Surface roughness of PI increased after Ar + ion bombardment. Increase of surface roughness of pre-treated PI improved the growth of Ni films in (111) preferential orientation due to the minimization of surface energy. Rearrangement of atoms due to enhanced surface diffusion caused by the ion bombardment reduced the residual stress of the films, and the pretreatment of PI substrate accelerated the decrease of film stress. The resistivity decreased and the TCR of the Ni films increased with the improvement of crystalline degree and the increase of grain size.

Luminescence effects of ion-beam bombardment of CdTe surfaces

In the present work, we report the effect of low-energy ion bombardment on CdTe surfaces. The effect is revealed by FESEM images and photoluminescence (PL) measurements carried out before and after irradiation of CdTe polycrystals by means of an ion-beam sputtering (IBS) system. An important improvement in the luminescence of CdTe was observed in the irradiated areas, related to defect-free surfaces.

Cooling Field and Ion-Beam Bombardment Effects on Exchange Bias Behavior in NiFe/(Ni,Fe)O Bilayers

The dependence of the cooling field and the ion-beam bombardment on the exchange bias effects in NiFe/(Ni,Fe)O bilayers were investigated. The positive exchange bias was found in the zero-field-cooled (ZFC) process whereas a negative exchange bias occurred in the FC process. The increased exchange field, H(ex) with increasing (Ni,Fe)O thicknesses indicates the thicker the AF (Ni,Fe)O, the stronger the exchange coupling between the NiFe layer and the (Ni,Fe)O layer. In addition, the dependence of the H(ex) (ZFC vs. FC) on the (Ni,Fe)O thicknesses reflects the competition between the applied magnetic field and the (Ni,Fe)O surface layer exchange coupled to the NiFe layer. Further, an unusual oscillating exchange bias was observed in NiFe/(Ni,Fe)O bilayers that results from the surface of the (Ni,Fe)O layer being bombarded with different Ar-ion energies using End-Hall deposition voltages (V(EH)) from 0 to 150 V. The behavior of the H(ex) and the H(c) with the V(EH) is attributed to the surface spin reorientation that is due to moderate ion-beam bombardment effects on the surface of the (Ni,Fe)O layer. Whether the (Ni,Fe)O antiferromagnetic spins are coupled to the NiFe moments antiferromagnetically or ferromagnetically changes the sign of the exchange bias.

Study on Al Alloy Surfaces Treated by Ion Beams

Plasma-enhanced ion beams are used for the surface modification of 2024 Al and 7075 Al alloy samples. The morphology of the treated surface of the samples is examined. The corrosion resistance and bending fatigue properties were measured on the treated and untreated samples. The effects of ion beam parameters are discussed. It is indicated that during the ion bombardment, craters are formed and surface melting is produced on the treated surfaces. The effects of ion beam bombardment are limited to the surface layer of samples. With the ion beam energies used in this study, improved corrosion resistance was obtained from the treated surfaces of the samples.

Effects of low-energy ion beam bombardment on biological cell envelopes

Low-energy ion beam biotechnology has seen rapid development worldwide in recent years. This is an important expansion of studies on ion beam modification of solid materials, vastly different from and more complex than the latter. Among other novelties, we have focused our interest on ion beam bombardment effects on plant and bacterial cell envelopes and tried to understand mechanisms involved in ion beam-induced gene transfer. Through a comprehensive investigation, we have discovered ion beam-induced formation of nanocrater-like structures in the cell envelope, a general phenomenon of ion beam bombardment of cells; these structures may act as pathways for exogenous macromolecule transfer. We have also quantitatively obtained abnormally great penetration depth and sputtering of ions in the cell envelope. All these results are significantly advantageous for ion beam processing of biological cells.

MeV Ion-Beam Bombardment Effects on The Thermoelectric Figures of Merit of Zn4Sb3 and ZrNiSn-Based half-heusler compounds

AbstractSemiconducting â-Zn4Sb3and ZrNiSn-based half-heusler compound thin films were prepared by co-evaporation for the application of thermoelectric (TE) materials. High-purity solid zinc and antimony were evaporated by electron beam to grow the â-Zn4Sb3thin film while high-purity zirconium powder and nickel tin powders were evaporated by electron beam to grow the ZrNiSn-based half-heusler compound thin film. Rutherford backscattering spectrometry (RBS) was used to analyze the composition of the thin films. The grown thin films were subjected to 5 MeV Si ions bombardments for generation of nanostructures in the films. We measured the thermal conductivity, Seebeck coefficient, and electrical conductivity of these two systems before and after 5 MeV Si ions beam bombardments. The two material systems have been identified as promising TE materials for the application of thermal-to-electrical energy conversion, but the efficiency still limits their applications. The electronic energy deposited due to ionization in the track of MeV ion beam can cause localized crystallization. The nanostructures produced by MeV ion beam can cause significant change in both the electrical and the thermal conductivity of thin films, thereby improving the efficiency. We used the 3ù-method measurement system to measure the cross-plane thermal conductivity ,the Van der Pauw measurement system to measure the cross-plane electrical conductivity, and the Seebeck-coefficient measurement system to measure the cross-plane Seebeck coefficient. The thermoelectric figures of merit of the two material systems were then derived by calculations using the measurement results. The MeV ion-beam bombardment was found to decrease the thermal conductivity of thin films and increase the efficiency of thermal-to-electrical energy conversion.

Anomalous positive exchange bias in Ni80Fe20∕NixFe1−xO thin-film bilayers induced by ion-beam deposition effects

We present results on a Ni80Fe20∕NixFe1−xO thin-film bilayer that shows a positive exchange bias loop shift of ∼90Oe at 10 K under zero-field-cooled conditions. Zero-field-cooled and field-cooled hysteresis loops were double shifted at temperatures below 200 K. This behavior is due to the presence of a range of antiferromagnetic crystallite sizes in addition to multiple magnetic phases (e.g., FeO, Fe2O3, and NiO). Furthermore, the positive exchange bias loop shift decreases linearly with increasing temperature, with a compensation temperature Tcomp∼220K, after which negative exchange bias is measured. This temperature dependence of the exchange bias reflects the competition between the Ni80Fe20 ferromagnet and antiferromagnetic Fe oxide and NiO phases as well as a range of local blocking temperatures. We attribute the appearance of a positive exchange bias loop shift at low temperatures to temperature-dependent changes in the interfacial pinning and exchange coupling due to a complex NixFe1−xO structure from energetic ion-beam bombardment effects during the film deposition.

Influence of negative metal ion bombardment on the properties of ITO/PET films deposited by dc magnetron sputtering

Transparent conducting indium tin oxide (ITO) thin films were deposited on a polyethylene terephthalate (PET) substrate at a low substrate temperature by dc magnetron sputtering using a negative metal ion source and an ITO target. During separate deposition runs, the cesium partial pressure was varied from 1 × 10 −3 to 2.2 × 10 -3 Pa to investigate the effect of ion beam bombardment on the surface morphological, electrical and optical properties of the films. The resistivity of ITO films decreased with P Cs and reached as low as 6.2 × 10 −4 Ω cm at P Cs of 1.7 × 10 −3 Pa. Optical transmittance compared with bare PET substrate also varied significantly with P Cs and the highest optical transmittance of 87% (at λ=550 nm) was obtained at P Cs of 1.7 × 10 −3 Pa. According to a result obtained by AFM, surface roughness of the ITO/PET film showed remarkable change from 2.8 to 1.1 nm with P Cs. However, above optimal P Cs condition (>1.7 × 10 −3 Pa), the electrical, optical property and surface morphological properties deteriorated. From SEM, AFM, and Hall measurements, relatively low resistivity and high transmittance of ITO film deposited at P Cs=1.7×10 −3 Pa is caused by an increase in charge carrier concentration and flat surface morphology with secondary negative metal ion beam bombardment.

Preparation of hydroxyapatite layer by ion beam assisted simultaneous vapor deposition

Hydroxyapatite layer was prepared by using ion beam assisted simultaneous vapor deposition. The method comprised of an electron beam heater and a resistance heater vaporizing CaO and P2O5, respectively, while an argon ion beam was focused onto the substrate to assist the deposition. The effects of ion beam assistance during deposition were investigated. All deposited layers were amorphous, regardless of the current density level of the ion beam. Post-heat treatment was applied to crystallize the deposited coatings. The Ca/P ratio increased with increasing ion beam current density presumably due to the high sputtering rate of P compared to that of Ca from the layer being coated. Annealing the samples increased the ratio even further due to the evaporation of P at high temperature. Significant improvement in the bond strength between the layer and the substrate was observed. The formation of an intermixed layer at the interface due to the effect of ion beam bombardment is believed to have caused such adhesion property.

The effect of ion beam bombardment on the properties of Ta(C)N films deposited from pentakis-diethylamido-tantalum

TaN or TaCN films were deposited using a single source, pentakis-diethylamido-tantalum as diffusion barrier for copper metallization. N- and Ar-ion beams with energy of 120 eV were used for bombarding the film during growth to improve the film quality. The films deposited using N-ion beam showed a resistivity of approximately 950 μΩ cm and a density of 7.65 g/cm 3. The use of the N-ion beam, however, drastically degraded the step coverage of the film (∼5% at the 0.5 μm contact holes with aspect ratio of 3:1). On the other hand, the films deposited using an Ar-ion beam showed a resistivity of approximately 600 μΩ cm and a density of 8.26 g/cm 3. The step coverage measured at the same contact was approximately 40%. The resistivity and density of the thermally-decomposed film were also measured for comparison and were found to be approximately 10 000 μΩ cm and 5.85 g/cm 3, respectively. Finally, the diffusion barrier performance of 50 nm thick films against Cu was investigated by X-ray diffractometry. The Cu/N- or Ar-ion beam bombarded film/Si structures showed formation of η″-Cu 3Si after annealing at 650 °C for 1 h, while Cu/thermally-decomposed film/Si showed this only after annealing at 600 °C.

Effects of ion beam bombardment on electrochromic tungsten oxide films studied by X-ray photoelectron spectroscopy and Rutherford back-scattering

The effect of ion bombardment on thermally evaporated and magnetron sputtered tungsten oxide films were investigated using X-ray photoelectron spectroscopy (XPS). Results show that irrespective of the porosity and crystallinity of the film samples formed with different techniques and conditions, ion bombardment induced preferential sputtering of oxygen, resulting in a decrease of oxygen/tungsten (O/W) ratio with increasing sputtering time. Samples experienced electrochromic switching cycles also show the same effect, except that a higher O/W ratio is detected because the tungsten oxide film reacts with the LiClO 4-propylene carbonate electrolyte. Angle-resolved XPS experiments further confirm preferential sputtering of oxygen, suggesting that ion beam sputtering used in XPS for pre-cleaning and depth profile analysis of tungsten oxide must be used with caution. Rutherford back-scattering gives more reliable composition data of tungsten oxide, since it does not involve any sputtering process.