Ag Ion Implantation Research Articles

Tailoring the structural and optical properties of TiN thin films by Ag ion implantation

Titanium nitride (TiN) thin films thickness of ∼260nm prepared by dc reactive sputtering were irradiated with 200keV silver (Ag) ions to the fluences ranging from 5×1015ions/cm2 to 20×1015ions/cm2. After implantation TiN layers were annealed 2h at 700°C in a vacuum. Ion irradiation-induced microstructural changes were examined by using Rutherford backscattering spectrometry, X-ray diffraction and transmission electron microscopy, while the surface topography was observed using atomic force microscopy. Spectroscopic ellipsometry was employed to get insights on the optical and electronic properties of TiN films with respect to their microstructure. The results showed that the irradiations lead to deformation of the lattice, increasing disorder and formation of new Ag phase. The optical results demonstrate the contribution of surface plasmon resonace (SPR) of Ag particles. SPR position shifted in the range of 354.3–476.9nm when Ag ion fluence varied from 5×1015ions/cm2 to 20×1015ions/cm2. Shift in peak wavelength shows dependence on Ag particles concentration, suggesting that interaction between Ag particles dominate the surface plasmon resonance effect. Presence of Ag as second metal in the layer leads to overall decrease of optical resistivity of TiN.

Effects of high-dose hydrogen implantation on defect formation and dopant diffusion in silver implanted ZnO crystals

This work reports on the effects of a deep high-dose hydrogen ion implant on damage accumulation, defect retention, and silver diffusion in silver implanted ZnO crystals. Single-crystal ZnO samples were implanted with Ag ions in a region ∼150 nm within the surface, and some of these samples were additionally implanted with hydrogen ions to a dose of 2 × 1016 cm−2, close to the depth ∼250 nm. Rutherford backscattering/ion channeling measurements show that crystal damage caused by Ag ion implantation and the amount of defects retained in the near surface region following post-implantation annealing were found to diminish in the case with the H implantation. On the other hand, the additional H ion implantation resulted in a reduction of substitutional Ag atoms upon post-implantation annealing. Furthermore, the presence of H also modified the diffusion properties of Ag atoms in ZnO. We discuss these findings in the context of the effects of nano-cavities on formation and annihilation of point defects as well as on impurity diffusion and trapping in ZnO crystals.

Fabrication of highly homogeneous surface-enhanced Raman scattering substrates using Ag ion implantation

In recent times, surface-enhanced Raman scattering (SERS) has attracted attention for its excellent potential application in chemical and biological detection. In this work, we demonstrate that a highly homogeneous SERS substrate can be realized by Ag ion implantation and the subsequent annealing process. Both the implantation and annealing parameters have been optimized for a high sensitivity SERS substrate. The SERS measurement indicates that a sample implanted by 20 kV Ag ions with a dosage of 3 × 1016 ions cm−2 exhibits the highest SERS activity. In addition, the SERS activity of the Ag-implanted substrates depends highly on the annealing temperature and time. Since none of the fabrication processes contain chemical reactions, our substrate is a clean system without any chemical residues.

Structural analysis and atomic simulation of Ag/BN nanoparticle hybrids obtained by Ag ion implantation

The present paper describes fabrication of Ag/BN nanoparticle hybrids by means of Ag ion implantation into the hollow BN nanoparticles (BNNPs) with a petal-like surface. The structural transformations occurring during Ag ion implantation into BNNPs are studied by low- and high-resolution transmission electron microscopy (TEM), high angle annular dark field scanning TEM (HAADF-STEM) paired with energy-dispersive X-ray (EDX) spectroscopy mapping. The experimental results are theoretically verified in the framework of the classical molecular dynamics (MD) method. Our results have demonstrated that by changing Ag ion energy in the range of 2–20kV it is possible to selectively fabricate Ag/BNNP nanohybrids with crystalline or amorphous BNNP structures and various Ag NPs distributions over the BNNP thicknesses.

In vitro studies on silver implanted pure iron by metal vapor vacuum arc technique

Pure iron has been verified as a promising biodegradable metal for absorbable cardiovascular stent usage. However, the degradation rate of pure iron is too slow. To accelerate the degradation of the surface of pure iron, silver ions were implanted into pure iron by metal vapor vacuum arc (MEVVA) source at an extracted voltage of 40keV. The implanted influence was up to 2×1017ions/cm2. The composition and depth profiles, corrosion behavior and biocompatibility of Ag ion implanted pure iron were investigated. The implantation depths of Ag was around 60nm. The element Ag existed as Ag2O in the outermost layer, then gradually transited to metal atoms in zero valent state with depth increase. The implantation of Ag ions accelerated the corrosion rate of pure iron matrix, and exhibited much more uniform corrosion behavior. For cytotoxicity assessment, the implantation of Ag ions slightly decreased the viability of all kinds of cell lines used in these tests. The hemolysis rate of Ag ion implanted pure iron was lower than 2%, which was acceptable, whereas the platelet adhesion tests indicated the implantation of Ag ions might increase the risk of thrombosis.

Structure and optical properties of ZnO with silver nanoparticles

Textured nanocrystalline ZnO thin films are synthesized by ion beam assisted deposition. According to X-ray diffraction data, the crystallite size is ~25 nm. Thin (~15 nm) ZnO layers containing Ag nanoparticles are formed in a thin surface region of the films by the implantation of Ag ions with an energy of 30 keV and a dose in the range (0.25–1) × 1017 ion/cm2. The structure and optical properties of the layers are studied. Histograms of the size distribution of Ag nanoparticles are obtained. The average size of the Ag nanoparticles varies from 0.5 to 1.5–2 nm depending on the Ag-ion implantation dose. The optical transmittance of the samples in the visible and ultraviolet regions increases, as the implantation dose is increased. The spectra of the absorption coefficient of the implanted films are calculated in the context of the (absorbing film)/(transparent substrate) model. It is found that the main changes in the optical-density spectra occur in the region of ~380 nm, in which the major contribution to absorption is made by Ag nanoparticles smaller than 0.75 nm in diameter. In this spectral region, absorption gradually decreases, as the Ag-ion irradiation dose is increased. This is attributed to an increase in the average size of the Ag nanoparticles. It is established that the broad surface-plasmon-resonance absorption bands typical of nanocomposite ZnO films with Ag nanoparticles synthesized by ion implantation are defined by the fact that the size of the nanoparticles formed does not exceed 1.5–2 nm.

A dual-emitting 4d-4f nanocrystalline metal-organic framework as a self-calibrating luminescent sensor for indoor formaldehyde pollution.

A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag(+) ions can tune the dual-emissive characters of the material. FA can interact with the Ag(+) ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection.

Optical, electrical and microstructural properties of nanocomposite Ag/diamond by Ag ion implantation and subsequent annealing

An optical-grade, free-standing diamond (FSD) film is prepared by home-made microwave plasma chemical vapor deposition reactor at a condition of input power 8 kW and gas pressure18 kPa. Then, it is implanted with 80 keV Ag ions up to a fluence of 5.0 × 1016 ions/cm2. After implantation, a subsequent annealing in Ar ambient at 500 °C is carried out to fabricate Ag nanoparticles (NPs). Grazing incidence x-ray diffraction results clearly showed that Ag NPs with a (111) orientation are effectively formed after 500 °C annealing. Results from field emission scanning electron microscope and atomic force microscope observations indicated that Ag NPs could aggregate and grow on the surface of the diamond film during the annealing process. The Hall effects results showed that Ag-implanted FSD film exhibited an enhanced carrier mobility of 34.7 cm2 V−1 S−1 after 500 °C annealing. Moreover, Raman spectroscopy results show that the damages of the Ag-implanted FSD film are essentially a little and the crystallinity is almost recovered by annealing, it is implied that the enhancement in carrier mobility could be attributed to the conductive paths provided by Ag NPs.

Local analysis of porous silicon structure fabricated by nontraditional approach

A comparison of experimental electron backscattering diffraction patterns for porous Si formed by ion implantation and thermal annealing is presented. For this purposes Ag-ion implantation into monocrystalline c-Si substrates at energy of 30 keV with dose of 1.5×1017 ion/cm2 was carried out. Surface nanoporous Si structures were studied by scanning electron microscope imaging and electron backscattering diffraction. Amorphization of Si after implantation and recrystallization of porous Si after annealing is observed. Ion implantation is suggested to be effective technique for a formation of nanoporous semiconductor layers, which could be easily combined with the crystalline substrate matrix for various applications.

Influence of biocompatible metal ions (Ag, Fe, Y) on the surface chemistry, corrosion behavior and cytocompatibility of Mg–1Ca alloy treated with MEVVA

Mg–1Ca samples were implanted with biocompatible alloy ions Ag, Fe and Y respectively with a dose of 2×1017ionscm−2 by metal vapor vacuum arc technique (MEVVA). The surface morphologies and surface chemistry were investigated by SEM, AES and XPS. Surface changes were observed after all three kinds of elemental ion implantation. The results revealed that the modified layer was composed of two sublayers, including an outer oxidized layer with mixture of oxides and an inner implanted layer, after Ag and Fe ion implantation. Y ion implantation induced an Mg/Ca-deficient outer oxidized layer and the distribution of Y along with depth was more homogeneous. Both electrochemical test and immersion test revealed accelerated corrosion rate of Ag-implanted Mg–1Ca and Fe-implanted Mg–1Ca, whereas Y ion implantation showed a short period of protection since enhanced corrosion resistance was obtained by electrochemical test, but accelerated corrosion rate was found by long period immersion test. Indirect cytotoxicity assay indicated good cytocompatibility of Y-implanted Mg–1Ca. Moreover, the corresponding corrosion mechanisms involving implanting ions into magnesium alloys were proposed, which might provide guidance for further application of plasma ion implantation to biodegradable Mg alloys.

Comparison of diffusion coefficients and activation energies for Ag diffusion in silicon carbide

Abstract The migration of silver (Ag) in silicon carbide (SiC) and 110mAg through SiC of irradiated tri-structural isotropic (TRISO) fuel has been studied for the past three to four decades. However, there is no satisfactory explanation for the transport mechanism of Ag in SiC. In this work, the diffusion coefficients of Ag measured and/or estimated in previous studies were reviewed, and then pre-exponential factors and activation energies from the previous experiments were evaluated using Arrhenius equation. The activation energy is 247.4 kJ·mol−1 from Ag paste experiments between two SiC layers produced using fluidized-bed chemical vapor deposition (FBCVD), 125.3 kJ·mol−1 from integral release experiments (annealing of irradiated TRISO fuel), 121.8 kJ·mol−1 from fractional Ag release during irradiation of TRISO fuel in high flux reactor (HFR), and 274.8 kJ·mol−1 from Ag ion implantation experiments, respectively. The activation energy from ion implantation experiments is greater than that from Ag paste, fractional release and integral release, and the activation energy from Ag paste experiments is approximately two times greater than that from integral release experiments and fractional Ag release during the irradiation of TRISO fuel in HFR. The pre-exponential factors are also very different depending on the experimental methods and estimation. From a comparison of the pre-exponential factors and activation energies, it can be analogized that the diffusion mechanism of Ag using ion implantation experiment is different from other experiments, such as a Ag paste experiment, integral release experiments, and heating experiments after irradiating TRISO fuel in HFR. However, the results of this work do not support the long held assumption that Ag release from FBCVD-SiC, used for the coating layer in TRISO fuel, is dominated by grain boundary diffusion. In order to understand in detail the transport mechanism of Ag through the coating layer, FBCVD-SiC in TRISO fuel, a microstructural change caused by neutron irradiation during operation has to be fully considered.

Diffusion of Ag, Au and Cs implants in MAX phase Ti3SiC2

MAX phases (M: early transition metal; A: elements in group 13 or 14; X: C or N), such as titanium silicon carbide (Ti3SiC2), have a unique combination of both metallic and ceramic properties, which make them attractive for potential nuclear applications. Ti3SiC2 has been considered as a possible fuel cladding material. This study reports on the diffusivities of fission product surrogates (Ag and Cs) and a noble metal Au (with diffusion behavior similar to Ag) in this ternary compound at elevated temperatures, as well as in dual-phase nanocomposite of Ti3SiC2/3C-SiC and polycrystalline CVD 3C-SiC for behavior comparisons. Samples were implanted with Ag, Au or Cs ions and characterized with various methods, including X-ray diffraction, electron backscatter diffraction, energy dispersive X-ray spectroscopy, Rutherford backscattering spectrometry, helium ion microscopy, and transmission electron microscopy. The results show that in contrast to immobile Ag in 3C-SiC, there is a significant outward diffusion of Ag in Ti3SiC2 within the dual-phase nanocomposite during Ag ion implantation at 873K. Similar behavior of Au in polycrystalline Ti3SiC2 was also observed. Cs out-diffusion and release from Ti3SiC2 occurred during post-implantation thermal annealing at 973K. This study suggests caution and further studies in consideration of Ti3SiC2 as a fuel cladding material for advanced nuclear reactors operating at very high temperatures.

AgNi alloy nanoparticles embedded SiO2 films: Synthesis and structure

AgNi alloy nanoparticles (NPs) embedded in SiO2 were prepared by sequentially implantation of 60keV Ni ions and 70keV Ag ions at the same fluence of 5.0×1016cm−2 and post-thermal annealing at 600°C in Ar atmosphere. UV–vis absorption spectroscopy study showed that the introducing of Ni atoms lead to dual absorption peaks centered at 406nm and 563nm. The incorporation of Ni elements in Ag NPs damped SPR absorption intensity. X-ray photoelectron spectroscopy and Grazing X-ray diffraction results were consistent with the presence of metallic Ag surrounded by Ni or NiO. Cross-sectional transmission electron microscopy observations further confirmed the fabrication of AgNi alloy NPs with high volume fraction.

Effects of Ti charge state, ion size and beam-induced compaction on the formation of Ag metal nanoparticles in fused silica

Metal nanoparticles formed by ion implantation in fused silica exhibit linear and nonlinear optical properties that can be altered by co-doping the silica substrate with transition-metal ions. For example, implantation of scandium in fused silica creates a directional optical dichroism due to the different spatial distribution of silver nanoparticles subsequently formed by Ag ion implantation. In this paper, we show that implantation of titanium ions alters the short- and intermediate-range order in the silica and thereby alters the diffusion and nucleation processes that lead to formation of silver nanoparticles. In particular, the dichroic response observed for Ag nanoparticles in Sc-implanted silica is, with one exception, in Ti-implanted silica. Compaction of the silica due to the ion implantation process appears to be similar for both Sc and Ti implantations, based on the observed shift of the 1,124 cm−1 transverse-optical phonon mode in the infrared reflectance spectrum. However, differences in chemical reactivity, bond lengths and electronic structure of Sc and Ti produce changes in electronic structure and strain that are sensitively reflected in the reflectance spectra of the Ag nanoparticles. These differences lead to modifications in the size, shape and spatial distributions of the silver nanoparticles and offer a powerful means of controlling their optical properties.

Fabrication of ultra-thin silicon nanowire arrays using ion beam assisted chemical etching.

Uniform dispersion of Au-Ag alloy nanoparticles underneath the surface of a Si wafer is realized via Au film pre-deposition and Ag ion implantation. The Au-Ag nanoparticles are used as catalysts in metal assisted chemical etching for fabricating Si nanowire arrays with average diameters of less than 10 nm. We find that the alloy catalysts introduced by ion implantation are the key to obtaining thin nanowire arrays and we also demonstrate that SiNWAs with various diameters could be simply produced by changing the thickness of the pre-deposited Au layer. Compared with the traditional process, ion beam assisted chemical etching is proven to be a convenient and efficient approach to fabricate ultra-thin SiNWAs on a large scale.

Effect of exposure environment on surface decomposition of SiC–silver ion implantation diffusion couples

SiC is a promising material for nuclear applications and is a critical component in the construction of tristructural isotropic (TRISO) fuel. A primary issue with TRISO fuel operation is the observed release of 110mAg from intact fuel particles. The release of Ag has prompted research efforts to directly measure the transport mechanism of Ag in bulk SiC. Recent experimental efforts have focused primarily on Ag ion implantation designs. The effect of the thermal exposure system on the ion implantation surface has been investigated. Results indicate the utilization of a mated sample geometry and the establishment of a static thermal exposure environment is critical to maintaining an intact surface for diffusion analysis. The nature of the implantation surface and its potential role in Ag diffusion analysis are discussed.

Ultraviolet photoluminescence from stressed silicon nanoclusters

Synthesis of UV light emitting stressed Si nanoclusters embedded in amorphous Si layer, using a dual Ag ion implantation technique has been reported. The stressed nanoclusters exhibit a very narrow photo-luminescence in UV regime at around 3.28 eV. Presence of metal ions like Ag, in the vicinity of Si nanoclusters enhances the luminescence due to localized surface plasmon resonance effect. The magnitude of stress has been calculated using Raman scattering method.

Enhanced osteoblast functions and bactericidal effect of Ca and Ag dual-ion implanted surface layers on nanograined titanium alloys.

To endow a Ti-based implant with enhanced osteogenic activity and antibacterial property, we herein modified nano-grained (NG) and coarse-grained (CG) Ti surface layers by the implantation of Ca and/or Ag ions, which were derived by surface mechanical attrition treatment (SMAT). The cellular adhesion, proliferation, differentiation (as marked by the osteogenesis-related gene expression, ALP activity and specific protein content) and extracellular matrix mineralization of hFOB1.19 osteoblasts, as well as the bacterial adhesion of Staphylococcus aureus and Escherichia coli on as-SMATed and different ion-implanted surfaces, were also investigated. The obtained results show that Ca and/or Ag ion implantation almost does not significantly alter the surface roughness and topography of the SMATed layers; moreover, it has little influence on the microstructure of the SMAT-achieved Ti nanograins. Furthermore, the implanted Ca and Ag are in the form of CaTiO3 and metallic Ag nanoparticles (NPs), respectively, and are embedded tightly in the Ti matrix. Significant enhancements of osteoblast functions are exhibited on the NG and ion-implanted NG surfaces compared to the CG and ion-implanted CG surfaces, which is related to the grain size and hydrophilicity of the surfaces. Although the Ca and Ag dual-ion implanted CG surface can simultaneously enhance the osteogenic activity and antibacterial properties compared to the CG surface, the enhancement of dual functions is more pronounced on the dual-ion implanted NG surface because the NG surface is more beneficial to the implantation of Ag and Ca ions compared to the CG surface. Although surface chemistry and hydrophilicity are responsible for the various antibacterial properties of the surfaces, the Ag NPs in the ion-implanted surfaces play a dominant role in the bactericidal ability compared to the hydrophilicity. Our study provides a promising means for designing biomaterial surfaces such that their osteoblast functions and antibacterial activity are perfectly balanced.

Enhancing Hydrogen Diffusion in Silica Matrix by Using Metal Ion Implantation to Improve the Emission Properties of Silicon Nanocrystals

Efficient silicon-based light emitters continue to be a challenge. A great effort has been made in photonics to modify silicon in order to enhance its light emission properties. In this aspect silicon nanocrystals (Si-NCs) have become the main building block of silicon photonic (modulators, waveguide, source, and detectors). In this work, we present an approach based on implantation of Ag (or Au) ions and a proper thermal annealing in order to improve the photoluminescence (PL) emission of Si-NCs embedded in SiO2. The Si-NCs are obtained by ion implantation at MeV energy and nucleated at high depth into the silica matrix (1-2 μm under surface). Once Si-NCs are formed inside the SiO2we implant metal ions at energies that do not damage the Si-NCs. We have observed by, PL and time-resolved PL, that ion metal implantation and a subsequent thermal annealing in a hydrogen-containing atmosphere could significantly increase the emission properties of Si-NCs. Elastic Recoil Detection measurements show that the samples with an enhanced luminescence emission present a higher hydrogen concentration. This suggests that ion metal implantation enhances the hydrogen diffusion into silica matrix allowing a better passivation of surface defects on Si NCs.

Effects of Ag-ion implantation on the performance of DSSCs with a tri-layer TiO2 film

Ag-ions take different roles in titania films as a function of the dose of implanted Ag ions.