Plasma Immersion Ion Implantation Method Research Articles

AZO work function enhanced by oxygen plasma immersion ion implantation

The surface of aluminum-doped ZnO (AZO) films was modified using the oxygen plasma immersion ion implantation method, which is also called O-PIII. The modified AZO films were analyzed by an X-ray photoelectron spectroscopy system (XPS), X-ray diffraction (XRD), a UV–visible spectrophotometer, atomic force microscopy (AFM), and a Kelvin probe instrument (KP). The results showed that O-PIII modification can further enhance the work function (WF) of AZO based on oxygen plasma (O-ICP) treatment. The optical characteristics of AZO thin films are nearly entirely preserved, and the surface morphology is enhanced. The variation in WF was strongly linked to the surface stoichiometry. The reduction of oxygen vacancies should be attributed to the high WF. The WF of the modified AZO films decreased rapidly with exposure time in the air promptly following O-ICP and O-PIII modification. Nonetheless, the O-PIII treatment had a longer-lasting effect.

Micro-galvanic effects of silver-containing titanium implants regulate the immune responses via activating voltage-gated calcium channels in macrophages

To explore the physiological mechanism of silver for the clinical application of silver-containing biomaterials and biomedical devices, the plasma immersion ion implantation method was used to prepare silver-doped titanium samples in this work. The findings disclosed that with the increase of the introduced Ag amount, the micro-galvanic effects formed by silver and the titanium matrix became stronger, which could stimulate the opening of voltage-gated calcium channels in macrophages to facilitate Ca2+ influx. The increase of intracellular Ca2+ concentration could induce macrophages to polarize towards the M1 phenotype by activating the Ca2+-dependent PKC-NF-κB signaling pathway, while it was more favorable to the polarization of M2 macrophages by improving the synthesis and secretion of calcium-dependent PGE2. Therefore, with the increase of Ag amount, the micro-galvanic effect was enhanced, and the anti-inflammatory responses of macrophages on samples were improved. Furthermore, the co-cultured bone marrow mesenchymal stem cells could inhibit the Ca2+ influx of the co-cultured macrophages to down-regulate the Ca2+-dependent PKC-NF-κB signaling pathway in macrophages and secrete PGE2 to promote the polarization of M2 macrophages, which weaken the inflammatory response. Our results indicate that the immune response can be regulated by the micro-galvanic effects of silver and titanium matrix, and provide new insights into designing and developing the silver-containing biomaterials with a desirable biological response.

Synergistic effects of immunoregulation and osteoinduction of ds-block elements on titanium surface

Ds-block elements have been gaining increasing attention in the field of biomaterials modification, owing to their excellent biological properties, such as antibiosis, osteogenesis, etc. However, their function mechanisms are not well understood and conflicting conclusions were drawn by previous studies on this issue, which are mainly resulted from the inconsistent experimental conditions. In this work, three most widely used ds-block elements, copper, zinc, and silver were introduced on titanium substrate by plasma immersion ion implantation method to investigate the rule of ds-block elements in the immune responses. Results showed that the implanted samples could decrease the inflammatory responses compared with Ti sample. The trend of anti-inflammatory effects of macrophages on samples was in correlation with cellular ROS levels, which was induced by the implanted biomaterials and positively correlated with the number of valence electrons of ds-block elements. The co-culture experiments of macrophages and bone marrow mesenchymal stem cells showed that these two kinds of cells could enhance the anti-inflammation and osteogenesis of samples by the paracrine manner of PGE2. In general, in their steady states on titanium substrate (Cu2+, Zn2+, Ag), the ds-block elements with more valence electrons exhibit better anti-inflammatory and osteogenic effects. Moreover, molecular biology experiments indicate that the PGE2-related signaling pathway may contribute to the desired immunoregulation and osteoinduction capability of ds-block elements. These findings suggest a correlation between the number of valence electrons of ds-block elements and the relevant biological responses, which provides new insight into the selection of implanted ions and surface design of biomaterials.

Metal Insulator Transition in Vanadium Dioxide Hydrated by Means of the Plasma-Immersion Ion Implantation Method

In the work, we explore the modification of the structure of vanadium dioxide films, as well as the metal-semiconductor phase transition in them, when hydrated by the method of plasma-immersion ion implantation. Based on a detailed X-ray analysis and the Raman spectra of the initial and hydrated films, it is shown that the plasma-ion modification of the transition and the metallization of vanadium dioxide (at a hydrogen concentration above 10at. %) are most likely associated with electron-correlation effects amplified by hydrogen implantation and an increase in the free charge carrier density in the material.

Effect of tungsten implantation on the switching parameters in V2O5 films

The paper examines the effect of doping with tungsten on switching in hydrated vanadium pentoxide films. The switching effect is associated with the metal-insulator transition in a vanadium dioxide channel that forms in the initial film due to the process of electrical forming (EF). Doping is carried out by the plasma immersion ion implantation method. It is shown that implanting small tungsten doses improves the switching parameters after EF. When implanting large doses, switching is observed without EF, and if EF is applied, the switching effect, on the contrary, disappears.

Surface insulating properties of titanium implanted alumina ceramics by plasma immersion ion implantation

The insulating property of the alumina ceramic in vacuum under high voltage is mainly limited by its surface properties. Plasma immersion ion implantation (PIII) is an effective method to modify the surface chemical and physical properties of the alumina ceramic. In order to improve the surface flashover voltage of the alumina ceramic in vacuum, titanium ions with an energy of about 20keV were implanted into the surface of the alumina ceramic using the PIII method. The surface properties of the as-implanted samples, such as the chemical states of the titanium, morphology and surface resistivity, were characterized by X-ray photoelectron spectroscopy, scanning electron microscope and electrometer, respectively. The surface flashover voltages of the as-implanted alumina samples were measured by a vacuum surface flashover experimental system. The XPS spectra revealed that a compound of Ti, TiO2 and Al2O3 was formed in the inner surface of the alumina sample. The electrometer results showed that the surface resistivity of the implanted alumina decreased with increased implantation time. In addition, after the titanium ion implantation, the maximum hold-off voltage of alumina was increased to 38.4kV, which was 21.5% higher than that of the unimplanted alumina ceramic.

Wettability and boiling heat transfer study of black silicon surface produced using the plasma immersion ion implantation method

Black silicon (BSi) has gained attention among renewable energy materials for its nanoscale surface structures. Here we present a new plasma immersion ion implantation (PIII) method to produce BSi, as fabricating nanoscale surface structure has drawn recent attention for improving phase change heat transfer. The wettability and boiling heat transfer performance of the BSi surface were measured and compared with the untreated silicon surface. The roughness and contact angle of the BSi surface become larger than that of silicon, which create more nucleation sites. However, the declined wettability leads to a greater possibility of bubble coalescence. This phenomenon increases the departure diameter and decreases the departure frequency, which worsens the boiling heat transfer. The PIII method is a promising treatment to produce nanostructures on silicon for its large-scale production ability. In further studies, different fabrication parameters would be used to change the surface characteristics using the PIII method to enhance the boiling heat transfer and the CHF of the BSi surface.

Adherence Enhancement of Metallic Film on PZT-Type Ceramic Using Nitrogen Plasma Implantation

Lead zirconate titanate (PZT)-type ceramics used as piezoelectric sensors have electrodes made by metallic film deposition on the ceramic substrate, which has low adherence on substrate surface. During the welding process in electronic component manufacture, the metallic film releases from surface due to the electrode delamination caused by the large difference in thermal expansion gradients between the film and ceramic. Delamination is a serious problem found in the manufacture of ceramic capacitors since the metallic electrode is split into several layers, leading to a component failure as the electrode is not in contact with the ceramic surface anymore. Therefore, in order to increase the film adherence on the ceramic it is proposed in this paper to treat the PZT samples covered with silver metallic films by means of plasma immersion ion implantation (PIII) technique using a high voltage 100-kV/1-μs stacked Blumlein pulser. By using this technique, it is shown that the mechanical adherence of the electrode metallic silver film is increased, which allows the welding process of terminals for the piezoelectric device manufacture without film release failure. Thermal stress relief treatment known as annealing process was also used in this paper as an alternative to the PIII method for increasing the film anchoring on ceramic substrate.

Magnesium ion implantation on a micro/nanostructured titanium surface promotes its bioactivity and osteogenic differentiation function.

As one of the important ions associated with bone osseointegration, magnesium was incorporated into a micro/nanostructured titanium surface using a magnesium plasma immersion ion-implantation method. Hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 30 minutes (Mg30) and hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 60 minutes (Mg60) were used as test groups. The surface morphology, chemical properties, and amount of magnesium ions released were evaluated by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, field-emission transmission electron microscopy, and inductively coupled plasma-optical emission spectrometry. Rat bone marrow mesenchymal stem cells (rBMMSCs) were used to evaluate cell responses, including proliferation, spreading, and osteogenic differentiation on the surface of the material or in their medium extraction. Greater increases in the spreading and proliferation ability of rBMMSCs were observed on the surfaces of magnesium-implanted micro/nanostructures compared with the control plates. Furthermore, the osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) genes were upregulated on both surfaces and in their medium extractions. The enhanced cell responses were correlated with increasing concentrations of magnesium ions, indicating that the osteoblastic differentiation of rBMMSCs was stimulated through the magnesium ion function. The magnesium ion-implanted micro/nanostructured titanium surfaces could enhance the proliferation, spreading, and osteogenic differentiation activity of rBMMSCs, suggesting they have potential application in improving bone-titanium integration.

Investigation of the possibility of unfiltered aluminium vacuum arc plasma application for high-frequency short-pulse plasma immersion ion implantation

Abstract This paper is devoted to the study of the possibilities of unfiltered aluminium vacuum arc plasma application for intermetallic layers formation using the high-frequency short-pulse plasma immersion ion implantation method. It is shown experimentally that the number density of aluminium macroparticles (MPs) on the substrate surface is decreased dramatically by 3 orders of magnitude when the ion-plasma substrate treatment time is increased from 30 s to 3 min at the bias potential −2 kV. It was shown that at high intensity low energy plasma immersion implantation of Al ions in Ti and Ni substrates a deep layer (several μm) of aluminium dopants with concentration in the range of (12–35) at% can be formed.

Influences of preparation methods on bipolar switching properties in copper nitride films

Copper nitride (CuxN) films were prepared by plasma immersion ion implantation (PIII) as well as by reactive magnetron sputtering (RMS). Based on X-ray diffraction (XRD) analysis, a semiconductive phase Cu3N could be found in the films prepared by both methods. On the other hand, a copper-rich conductive phase Cu4N was observed only in the film prepared by PIII, in which gradually distributed nitrogen could be identified by secondary ion mass spectroscopy (SIMS) analysis. The resistive switching properties have been studied after depositing Ni as the top electrode. The Ni/CuxN/Cu memory devices prepared by PIII method showed a forming-free characteristic with a low operation voltage of ±0.2V, excellent DC and AC endurance performances at least longer than 600 times and 105 times with resistance window of 50 and 12 respectively. On the contrary, the resistive switching behavior for the device prepared by RMS needed a forming process and was unstable. The excellent performances in PIII prepared films were attributed to the coexistence of metallic Cu4N phase and gradually decreased nitrogen concentration. It was supposed that the Cu atoms bridge the small gaps between the bottom and top electrodes and form the conducting filaments.

The effect of pore characteristics on Ni suppression of porous NiTi shape memory alloys modified by surface treatment

The surfaces of porous NiTi shape memory alloys (SMAs) with different pore characteristics were modified by combined treatment of passivation and oxygen plasma immersion ion implantation methods. It has been found that the pore characteristics play an important role in improving Ni suppression performance. It is helpful to have large pore size and high pore interconnectivity for enhancing the Ni suppression performance of modified porous NiTi SMAs.

Tribological changes on SS304 stainless steel induced by nitrogen plasma immersion ion implantation with and without auxiliary heating

In order to achieve quite thick treated layers with reasonable thickness uniformity in SS304 steel, the plasma immersion ion implantation (PIII) process was run in high-temperature, up to 350 °C, to induce high thermal diffusion but avoid the white layer formation. In these experiments, we heated the sample-holder with a shielded resistive wire properly wound around it and subjected the SS samples to nitrogen glow discharge PIII with relatively low voltages (10 kV) in different temperatures. We also treated the SS samples by the traditional PIII method, slowly increasing the high voltage pulse intensities, until 14 kV at the end of processing, reaching temperatures of up to 350 °C. These modes of treatments were compared with respect to nitrogen implantation profiles, X-ray diffraction, tribology and mechanical properties. X-ray diffraction results indicated a much higher efficiency of auxiliary heated PIII mode compared to the ordinary PIII. Very prominent γ N peaks were observed for the first mode, indicating large concentration of nitrogen in thick layers, confirmed by the nitrogen profiles measured by GDOS and AES. Improved mechanical and tribological properties were obtained for SS304 samples treated by the PIII with auxiliary heating, more than for ordinary PIII. Hardness was enhanced by up to 2.77 times, as seen by nanoindentation tests.

Tribological effects of plasma immersion ion implantation heating treatments on Ti–6Al–4V alloy

In order to achieve improved surface in components with high reliability required by the tool or metallurgical industries by means of plasma immersion ion implantation (PIII), it is necessary to obtain quite thick treated layers with reasonable thickness uniformity. One effective way to achieve such a thick nitrogen-rich layer in Ti–6Al–4V alloy is to run PIII process in high temperatures of about 800 °C. In these experiments, we heated the sample-holder and subjected the Ti–6Al–4V samples to nitrogen glow discharge PIII with relatively low peak voltages (5 kV). We also treated the Ti–6Al–4V samples by the traditional PIII method, increasing slowly the high voltage pulse intensities, and at the end of processing, reaching temperatures of up to 350 °C. These modes of treatments were compared with respect to nitrogen implantation profiles, tribological and mechanical properties. Nitrogen profiles measured by AES showed that auxiliary heating leads to richer and deeper layers. The best results were obtained for the samples treated for 4 h that, after 25,000 cycles in unlubricated pin-on-disk test, presented very small wear (reduction of 89%). In spite of friction coefficient being higher in the beginning of the test, probably due to the increase of the average roughness (Rms) in the surface of the treated material, it decreases when the rough surface wears away, due to the reduction of frictional force necessary to slide the pin on the sample. The material treated at 800 °C presents high wear resistance, which is desired in this alloy, that normally possesses excellent mechanical properties, however, poor tribological properties.

Structure and properties of silver-containing a-C(H) films deposited by plasma immersion ion implantation

In this study, we have grown silver-containing hydrogenated (a-C:H) and non-hydrogenated (a-C) amorphous carbon coatings by two plasma immersion ion implantation methods: I) chemical vapor deposition of methane combined with pulsed filtered cathodic arc deposition of silver, and II) by alternating arc pulses from graphite and silver in a dual cathodic arc plasma source. This unique “bias selective” feature of the deposition system allowed the deposition of silver with the substrates at ground and avoided the sputtering of the grown a-C film. Chemical composition of the samples was analyzed by acquiring their compositional depth-profiles using radio-frequency Glow Discharge Optical Emission Spectroscopy (rf-GDOES), while the microstructural properties were analyzed by X-ray absorption near edge spectroscopy (XANES) and Raman spectroscopy. In this contribution, we compare mechanical and biomedical properties by means of nanoindentation and cell viability tests, respectively, of a-C(H) films obtained by two different plasma immersion ion implantation techniques.

Application of Plasma Immersion Ion Implantation for Surface Modification of Nickel-titanium Rotary Instruments

By means of X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC), this study set out to investigate the application of plasma immersion ion implantation (PIII) for the surface modification of ProTaper NiTi rotary instruments. This study was undertaken because the PIII method was perceived to have the potential of developing into a standard surface modification technique that improves clinical quality and outcome. Specimens received nitrogen ion or nitrogen plus argon ion implantation. XPS analyses with and without argon ion etching were obtained for all specimens. In addition, DSC analysis was performed to investigate the phase transformation behavior of the bulk material. Results indicated that the surfaces of NiTi instruments were successfully modified by nitrogen PIII, whereby a light golden TiN layer was yielded. Moreover, the PIII technique did not alter the superelastic character of NiTi instruments because it was carried out at near-room temperature. We thus concluded that nitrogen PIII is a promising surface modification technique to improve the surface characteristics of NiTi rotary instruments.

Wear resistant and anti-corrosive treatment for TI–6AL–4V using metal vapor vacuum arc source in comparison with plasma immersion ion implantation

This study utilizes two ion-implantation methods, plasma immersion ion implantation (PIII) and metal vapor vacuum arc (MeVVA), to prepare Ti–N phases on the surface of Ti–6Al–4V. By the nitrogen PIII method, both nitrogen and minor oxygen species are simultaneously attracted by the negatively charged substrate. The penetration of N and O interstitial elements to an extensible depth is possible owing to the effect from the negatively charged target. The nitrogen PIII treatment does not produce a novel Ti–N phase. As a result, the modified surface does not behave anticorrosive. The H n and the E determined by nanoindentation also remain unchanged. It is still potential to apply this non-directional treatment by increasing bias voltage of the target, coating pure titanium on Ti–6Al–4V, and adjusting the regeneration process of nitrogen ions. The MeVVA treatment creates a novel αTiN 0.3 (011) phase on Ti–6Al–4V in present study. It signifies that the interactions between kinetic Ti ions of varied energies and minor nitrogen molecules, with minor participation of oxygen, are highly feasible. The novel ion-implanted Ti–N phase is corrosion resistant, which is capable to reduce passivation current density by forming a passive film. Moreover, the MeVVA-treated surface is surface-hardened; the E is simultaneously increased. The increase of nano mechanical properties can be visualized by 3D images using Nano Vision and determined by analyzing the tip/surface impact structure on the indentation site.

Measurements of secondary electron emission and plasma density enhancement for plasma exposed surfaces using an optically isolated Faraday cup

We present secondary electron yield and plasma enhancement factor data for silicon surfaces exposed to Ar, He, N2, O2, H2, and BF3 plasmas, for incident ion energies from 0.5–10 keV. A fiber-optic isolated Faraday cup was used to directly measure the ion current Jion, allowing a direct measurement of the secondary electron yield. This method automatically accounted for the effect of pulse-induced plasma density enhancement due to the ionization of neutral gas by accelerated secondary electrons, which we observed and measured quantitatively. The values of the secondary electron yields measured by this method were higher than published values measured by the conventional (ultraclean surface and ultrahigh vacuum) methods but lower than published values measured by previous plasma immersion ion implantation methods.