Ni Ion Implantation Research Articles

Formation of Anticorrosion Clusters on Anodic Alumina Films by Ni Ion Implantation

Formation of clusters with high corrosion resistance on anodic films of Aluminum by Ni ions implantation was studied. Ni ions were implanted in anodic films of 1070 aluminum at an energy of 40 keV with dose of 5.0×1017 ions/cm2. XPS analysis reveals that Ni is present in the states of metallic Ni and NiO on the surface of the anodic film. Electrochemical results show that anodic films with Ni ions implantation provide relatively higher corrosion resistance in NaCl solution. The anti-corrosion clusters on the surface of anodic films should be the main reason for better corrosion resistance of the implanted samples.

Optical and magnetic properties of Ni nanoparticles in rutile formed by Ni ion implantation

Crystalline Ni nanoparticles in the near surface of TiO2 (rutile) have been synthesized by Ni ion beam implantation at room temperature to a fluence of 1×1017∕cm2. Transmission electron microscopy, optical absorption spectroscopy, and a superconducting quantum interference device magnetometer have been utilized to characterize the nanostructure, optical and magnetic properties of Ni particles in TiO2. Crystalline Ni nanoparticles with dimensions ranging 3–20 nm formed in the near surface of rutile, which caused a broad absorption band from 700 nm in the optical absorption spectrum. Magnetic measurement indicated that the coercive force of Ni nanoparticles was about 210 Oe at 10 K. The superparamagnetism of the nanoparticles was observed above blocking temperature T=85K.

Vertically Aligned Carbon Nanotubes Growth Using Self-assembled Ni Nanoparticles Produced by Ion Implantation

ABSTRACTAn alternative method for seeding catalyst nanoparticles for carbon nanotubes and nanowires growth is presented. Ni nanoparticles are formed inside a 450 nm SiO2 film on (100) Si wafers through the implantation of Ni ions at fluences of 7.5×1015 and 1.7×1016 ions cm−2 and post-annealing treatment at 700, 900 and 1100 °C. After exposed to the surface by HF dip etching, the Ni nanoparticles are used as catalyst for the growth of vertically aligned carbon nanotubes by direct current plasma enhanced chemical vapor deposition.

Optical properties and structure characterization of sapphire after Ni ion implantation and annealing

Implantation of 64keV Ni ions to sapphire was conducted at room temperature to 1×1017ions∕cm2 with a current density of 5 or 10μA∕cm2. Metallic Ni nanoparticles were formed with the 5μA∕cm2 ion current and the NiAl2O4 compound was formed with the 10μA∕cm2 ion current. The crystals implanted with both current densities were annealed isochronally for 1h at temperatures up to 1000°C in steps of 100°C in an ambient atmosphere. Optical absorption spectroscopy, x-ray diffraction, transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy have been utilized to characterize the samples. The surface plasmon resonance (SPR) absorption band peaked at 400nm due to the Ni nanoparticles shifted toward the longer wavelength gradually with the annealing temperature increasing from 400to700°C. The SPR absorption band disappeared after the annealing temperature reached 800°C. NiO nanoparticles were formed at the expense of Ni nanoparticles with an increasing annealing temperature. The TEM analyses revealed that the nanoparticles grew to 6–20nm and migrated toward the surface after annealing at 900°C. The absorption band at 430nm from Ni2+ cations in NiAl2O4 did not shift with the increasing annealing temperature.

Magnetic nano-particles of Ni in MgO single crystals by ion implantation

Magnetic Ni nano-particles in the near surface regions of MgO single crystals have been synthesized by 64keV Ni ion implantation to 1×1017cm−2 followed by thermal annealing. Transmission electron microscopy (TEM) and magnetic properties measurement system (MPMS) equipped with a superconducting quantum interference device (SQUID) detector have been employed to characterize the microstructure and magnetic properties of the Ni nano-particles. The average particle size ranges 3–5nm in the as-implanted sample and 8–10nm in the annealed sample. The orientation of Ni particles is perfectly matched with that of the MgO matrix. The M–H hysteresis loop measured at 10K revealed the coercivity, Hc, ∼195Oe. The superparamagnetism of Ni particles was evident in as-implanted sample at the temperature above 35K but did not show in the annealed sample.

Effects of thermally-activated diffusion on 72 keV Ni ion implantation into Cu targets at elevated temperatures

This work experimentally and theoretically investigates the effects of thermally-activated diffusion on the depth profiles of nickel atoms in copper. Nickel ions of 72keV and 5×1015ions/cm2 were implanted into copper targets at elevated temperatures of 200, 400 and 500°C, respectively. The experimental nickel depth profiles were obtained by the secondary ion mass spectrometry (SIMS). The calculated profiles were obtained using a thermally-activated diffusion model in which both the radiation-enhanced diffusion (RED) and radiation-induced segregation (RIS) are considered. Furthermore, lattice dilation and preferential sputtering were taken into account by means of an appropriate coordinate transformation. The results indicated a strong temperature-dependence of nickel depth profiles. In addition, the nickel depth profiles tend to broaden and surface concentration increase with temperatures.

Prediction of intermetallics formation during metal ion implantation into Al at elevated temperature

The model of effective heat of formation in metal-Al binary system proposed by Pretorius et al. was developed based on characteristics of the solid-state reaction at interface to predict the formation of intermetallics during metal ion implantation into Al substrate at elevated temperature. For the Fe, Hf, Mo, Nb, Ni, Ta and Zr ion implantation with the ion energy of 50–140keV under the ion current density of 10–60μA/cm2 into Al substrate to the implantation dose of 1017–1018 ions/cm2 at the elevated temperature ranging from 300°C to 600°C, the model of effective heat of formation predicted the formation of intermetallics Al13Fe4, HfAl3, MoAl12, NbAl3, NiAl3, TaAl3 and ZrAl3, which were consistent with the experimental results. Taking the kinetic factors and the limitation of thermodynamic data into account, the model of effective heat of formation explained the formation of metastable intermetallics Cr14Al86 at the lower temperature of 400°C and of the stable intermetallics Cr2Al13 at the higher temperature of 510°C, and the formation of simple intermetallics VAl3 relative to complex intermetallics V4Al23, VAl7, and VAl10, for the Cr and V ion implantation into Al substrate, respectively, at the elevated temperature up to 510°C.

Low-temperature epitaxial Ni silicidation: The role of hyperthermal species

We present the results of Ni silicidation on a Si111 surface employing a mass-selected hyperthermal ion beam at 100 eV and discuss the reaction mechanism compared with the conventional Ni silicidation process. It is found that the Ni silicide formation using this technique is different from that achieved by conventional methods such as high-energy Ni-ion implantation or evaporation with thermal species. Namely, the Ni silicide phase formed at 230 degrees C using hyperthermal ions in this study is Ni-rich Ni2Si, in contrast to Si-rich disilicide NiSi2, ordinarily formed when high-energy Ni ions or thermal Ni beams react with Si at elevated temperatures. In addition, this layer is formed epitaxially on Si in spite of a low substrate temperature of 230 degrees C, while a polycrystalline Ni silicide layer is formed with conventional Ni-rich silicidation. This suggests that the reaction mechanism of the silicide formation with hyperthermal Ni particles is different from that using higher- or thermal-energy Ni particles. The atomic rearrangement induced by the thermal spikes most likely plays an important role in the Ni silicidation process employing hyperthermal species.

Effect of pre-Co-deposition Ni ion implantation on the stress level of CoSi2 films on Si(1 0 0)

The effect of pre-Co-deposition Ni ion implantation on the stress level of CoSi2 film formed by deposition of Co films on Si(100) substrates and subsequent ex situ rapid thermal annealing was investigated. X-ray diffraction was employed to measure the tensile stress in the CoSi2 films. It was found that the pre-Co-deposition Ni ion implantation was effective in reducing the stress level of CoSi2 films and the stress decreased linearly with the increase of reserved Ni ion implantation dose. In the present study, reduced lattice mismatch was proposed to explain the reduction of internal stress in CoSi2 films.

Effects of High Dose Ni, Fe, Co, and Mn Implantation into SnO[sub 2

The effects of high dose (3 3 1016 cm22) implantation of Ni, Fe, Co, or Mn ions into bulk, single-crystal SnO2 substrates carried out at substrate temperature of ;350 C to avoid amorphization of the implanted region on the magnetic properties of the material are reported. X-ray diffraction showed no evidence of secondary phase formation in the SnO2 . The Mn-implanted samples remained paramagnetic, as also reported for samples doped during thin film growth, but the Fe, Co-, and Ni-implanted SnO2 showed evidence of hysteresis with approximate Curie temperatures of ;120 K ~Co and Cr! or 300 K ~Fe!. The carrier density in the implanted region appears to be too low to support carrier-mediated origin of the ferromagnetism and formation of bound magnetic polarons may be one explanation for the observed magnetic properties. The much reduced Curie temperature seen in Co-implanted SnO2 compared to material doped during pulsed laser deposition suggests the residual implant damage degrades the magnetic properties.

Optical properties of metallic nanoparticles in Ni-ion-implanted α-Al2O3 single crystals

64 keV Ni ion implantation was performed at room temperature up to a dose of 1×1017 cm−2 in α-Al2O3 single crystals. The charge states, structure, and optical properties of metallic embedded Ni nanoparticles were studied by using x-ray photoelectron spectroscopy (XPS), transmission electron microscopy, and optical spectroscopy, respectively. XPS analysis showed that implanted Ni ions are mainly in charge state of metallic Ni0. Nanoparticles distributed from the surface to 30 nm below the surface were observed in a high-angle annular dark-field image. The size of nanoparticles ranges from 1 to 5 nm in diameter. A high-resolution electron microscopy image indicated the Ni-implanted area had been entirely amorphized. A new broad absorption band centered at 400 nm appeared in the optical absorption spectrum of the as-implanted crystal, due to surface plasma resonance of Ni nanoparticles. We did not find any emission band in the as-implanted sample under a Xe lamp excitation wavelength of 250–430 nm in a spectrophotometer.

Dynamics of photoluminescence in GaInNAs saturable absorber mirrors

Femtosecond time-resolved photoluminescence experiments have been used to study the nonlinear dynamics of novel monolithic GaInNAs/GaAs semiconductor saturable absorber mirrors at 1.08 and 1.55 μm. The mirror structures were grown using molecular-beam epitaxy followed by Ni-ion implantation and thermal annealing. We present photoluminescence measurements showing the critical role of post-growth processing on the response time of GaInNAs/GaAs absorber mirrors.

Effect of Fe and Ni ion implantation on the magnetoresistance of La0.7Sr0.3MnO3 thin films

Implantation of 56Fe and 58Ni ions with low and moderate doses is employed to create lattice disorder and point defects in order to study their influence on the magnetoresistance of La0.7Sr0.3MnO3 thin films. Two step ion implantation was carried out to distribute the implanted species across the whole layer thickness. The total dose was divided in the relation 1:2.5 on the energies 120 and 350 keV and varied between 3.5 × 1013 cm–2 and 5 × 1015 cm–2. RBS of He+ ions in random and channeling direction was used to detect the radiation damage. With increasing implantation dose the temperature of maximum magnetoresistance shifts to lower values. The low temperature transition from metallic conductivity to an increase of resistivity with decreasing temperature and the strong scattering of the resistance values in this region observed for medium implantation doses are discussed as due to percolation in an inhomogeneous state of coexisting ferromagnetic metallic and antiferromagnetic insulating clusters.

Study of optical properties and TEM of Nanoparticles in Ni+-implanted Sapphire

ABSTRACT64-keV Ni ion implantation was performed at room temperature up to a dose of 1×1017 cm-2 in α-Al2O3 single crystals. The charge states, structure and optical properties of metallic embedded Ni nanoparticles were studied by using X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and optical spectroscopy, respectively. XPS analysis showed that implanted Ni ions are mainly in charge state of metallic Ni0. Nanoparticles distributed from the surface to 30 nm below the surface were observed in a bright-field cross-sectional image. The size of nanoparticles ranges from 1 to 5 nm in diameter. A selected area electron diffraction (SAED) pattern shows Ni nanoparticles with lattice parameter a = 0.352 nm. A high-resolution electron microscopy (HREM) image indicated the Ni-implanted area had been entirely amorphized. A new broad absorption band centered at 400 nm appeared in the optical absorption spectrum of the as-implanted crystal, due to surface plasma resonance (SPR) of Ni nanoparticles.

Effects of stress on electrical transport properties of nickel silicide thin layers synthesized by Ni-ion implantation

Nickel disilicide layers were prepared by nickel ion implantation into silicon substrates using a metal vapor vacuum arc ion source at various beam current densities to an ion dose of 3×1017 cm−2. The as-implanted and annealed samples were characterized by using Rutherford backscattering spectrometry, x-ray diffraction, micro-Raman spectroscopy, electrical resistivity, and Hall-effect measurements. Residual stress in the NiSi2 layers was determined using the sin2 ψ method of x-ray diffraction, assuming that a biaxial stress state exists in the layers and that the elastic properties of the layers are isotropic. The temperature dependence of the sheet resistivity and the Hall mobility from 30 to 400 K showed peculiar peak and valley features varying from sample to sample, depending on the preparation conditions. However, after annealing, the differences between samples seemed to have diminished in that they all showed similar shapes in both the sheet resistivity versus temperature and the Hall mobility versus temperature curves. It was also shown that the electrical transport properties were highly correlated with the stress in the layers.

Refractive index profiles of ion implanted waveguides in thulium sodium yttrium tungstate

Planar waveguides were first formed in thulium sodium yttrium tungstate (Tm:NaY(WO 4) 2) crystals by the implantation of MeV He, P and Ni ions with certain doses at room temperature, respectively. The refractive index profiles of the three ion implanted waveguides were found different to some extent. The present data show that He + ion implanted waveguides in Tm:NaY(WO 4) 2 should be the typical barrier type one, while a combination of radiation damage and radiation enhanced diffusion may be responsible for the refractive index profiles of the MeV Ni + and P + ion implanted waveguides in Tm:NaY(WO 4) 2.

Modification of wear and fatigue characteristics of Ti–V–Al alloy by Cu and Ni ion implantation and high-current electron beam treatment

After Cu (60 keV, D =2×10 17 cm −2 ) and Ni (40 keV, D =5×10 16 cm −2 ) ion implantation and subsequent high-current electron beam (HCEB) treatment, Ti 41–V 41–Al 18 alloy has been investigated. In addition to implanted Cu and Ni ions, high concentration of oxygen of about 14 at% and carbon of about 15 at% were found in the layer of 60 nm. The surface alloy layer was composed of a number of structures: the grains of a dislocation substructure (2×10 10 cm −2), the grains with plates, and the grains with a packed martensite. The disorientation of regions was observed. The implanted alloy was found to have a decreased wear ability as well as an increased fatigue limit for cycling loads to 30%. After Cu, Ni implantation and HCEB treatment this fatigue limit increased to 60%, the subsequent furnace annealing increasing it to 90%. Hardness also increased and the value of friction coefficient decreased by a factor of 1.8 after this double implantation and HCEB treatment.

Mechanical properties of ion-implanted polycarbonate

The technique of ion implantation was employed for improving surface hardness and wear resistance of polycarbonate (PC). The samples of PC were implanted separately with C, Al, Ti, Fe and Ni ions to four doses of 2×10 15 ions cm −2, 1×10 16 ions cm −2, 5×10 16 ions cm −2 or 1×10 17 ions cm −2. Wear tests showed that the wear-resistance of PC was improved significantly and the friction coefficient was reduced after ion treatment, 2×10 15 ions cm −2 C ion implantation produced the largest improvement in wear-resistance by a factor of 19 times and the friction coefficient was reduced by 20%. The nano-hardness increased from 0.283 GPa for the pristine PC to 0.712 GPa for 2×10 15 ions cm −2 C-implanted PC and 1.032 GPa for 1×10 16 ions cm −2 Ni-implanted PC. TRIM96 calculation revealed that ionization energy loss, vacancy energy loss and the difference in the energy loss for ionization and vacancies of Ni near the surface were more than those of the four other ions, and this was related to the largest improvement of surface hardness for Ni ion implantation. IR spectra of 2×10 15 ions cm −2 C-implanted PC indicated that the surface of samples was moisture-retentive and formed a new carbonyl group.

Pattern evolution ofNiSi2grown on a Si surface upon high-current pulsed Ni-ion implantation

Growth of surface fractal patterns of Ni disilicide was induced by high-current pulsed Ni ion implantation into Si wafers. By increasing the substrate temperature and the supplemental Ni deposited on Si wafers, the fractal dimensions were determined and found to increase from less than 1.64, corresponding to that of cluster-diffusion-limited aggregation, to beyond the percolation threshold of 1.88, and eventually up to 2.0 of a uniform ${\mathrm{NiSi}}_{2}$ layer on the Si surface with fine grains. The mechanism of fractal pattern evolution is discussed, based on the consideration of the dynamic process of high-current pulsed metal-ion implantation.

Structure analysis by diffraction of amorphous zones created by Ni ion implantation into pure Al

The implantation of Ni ions into pure Al leads to the formation of ∼10 nm amorphous zones (AZ) which induce diffuse rings in the diffraction pattern in addition to the diffraction spots of the crystal. Measurements by energy dispersive spectrometry and electron energy loss spectrometry attributed to the amorphous zones an average Ni concentration of 25 at%. The exact structure of these AZ is still unknown. The structure is characterized here by both the total and partial radial distribution functions (RDF). Structure factor deduced from experiments is compared to calculated one. For this purpose, molecular dynamic (MD) simulations are used to model the AZ structure. The RDF are determined using this structure and analytical calculation of the diffraction pattern is achieved. Simulations of the diffraction pattern of the simulated MD sample using both a kinematic and a dynamic approach are achieved to refine the analytical procedure used on the experimental diffraction patterns. It appears that the amorphous structure is well reproduced by the MD simulations. Analytical calculation reveals the presence of a well-established chemical order in the amorphous material.