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A method is proposed for improving the performance properties of various materials, based on the synergy of high-intensity ion implantation and simultaneous energy impact on the surface, aimed at creating deep ionalloyed layers. Its implementation requires the use of repetitively-pulsed high-power density beams of metal and gas ions of submillisecond durations. This article presents the results of experimental studies on forming pulsed high-intensity titanium ion beams from vacuum arc plasma. The effect of the cell size of the grid electrode, shaped as a part of a sphere, on the focusing and transport efficiency is studied. A possibility of ballistic focusing of a titanium ion beam with a pulse duration from 150 to 500 μs and a power density of up to 100 kW/cm2 is experimentally shown. [ABSTRACT FROM AUTHOR]

The plasma physics of dielectric barrier discharges (DBD) for carrying out ion implantation in insulators is investigated. A hollow cathode DBD excited by high-voltage pulses is suitable for ion bombardment of the surfaces of insulating tubing, porous material, particles and sheets. Plasma immersion ion implantation of insulating surfaces is useful for many applications in medicine and engineering. The ion bombardment of glass is useful for cleaning and surface modification. The ion implantation of polymers creates radicals that are able to bind molecules to their surfaces for applications in medical procedures and diagnostics. A wire diagnostic probe and optical emission spectroscopy are used for experimental work. A theory based on mutual capacitance is developed to convert data from the probe to give implanted charge as a function of pressure, voltage and pulse duration. We find the operating conditions that allow for charge to be implanted and those that achieve the highest implanted charge. [ABSTRACT FROM AUTHOR]

Production costs and energy efficiency are the main priorities for the photovoltaic (PV) industry (COP21 conclusions). To lower costs and increase efficiency, we are proposing to reduce the number of processing steps involved in the manufacture of N-type Passivated Rear Totally Diffused (PERT) silicon solar cells. Replacing the conventional thermal diffusion doping steps by ion implantation followed by thermal annealing allows reducing the number of steps from 7 to 3 while maintaining similar efficiency. This alternative approach was investigated in the present work. Beamline and plasma immersion ion implantation (BLII and PIII) methods were used to insert n-(phosphorus) and p-type (boron) dopants into the Si substrate. With higher throughput and lower costs, PIII is a better candidate for the photovoltaic industry, compared to BL. However, the optimization of the plasma conditions is demanding and more complex than the beamline approach. Subsequent annealing was performed on selected samples to activate the dopants on both sides of the solar cell. Two annealing methods were investigated: soak and spike thermal annealing. Best performing solar cells, showing a PV efficiency of about 20%, was obtained using spike annealing with adapted ion implantation conditions. [ABSTRACT FROM AUTHOR]

The use of plasma immersion ion implantation (PIII) is a relevant approach for the development of advanced solar cells technologies at lower cost (€/W p ). In this paper, we report on the development of homogeneous boron (B) doping of n-type crystalline silicon (cSi) substrate by the PIII technique. Using diborane (B 2 H 6 ) as gas precursor, various doping profiles were identified fitting the requirements for boron-doped emitters in n-type PERT solar cells. Particularly, saturation current density (J 0e ) of 50 fA/cm 2 were achieved on symmetrical samples for a 94 Ω/sg textured B-emitter passivated with SiO 2 /SiN stack. Bifacial n-type Passivated Emitter Rear Totally-diffused (n-PERT) solar cells were fabricated using the PIII technology and conversion efficiencies up to 19.8% on 239 cm 2 Cz-Si wafers were obtained. As a consequence, these results indicate that PIII can compete with beamline technology but will have lower running cost. It is therefore a promising technology to create high efficiency cSi solar cells. [ABSTRACT FROM AUTHOR]

We investigate the electrical properties and dopant profiles of boron emitters performed by plasma immersion ion implantation from boron trifluoride (BF3) gas precursor, thermally annealed and passivated by silicon oxide/silicon nitride stacks. High thermal budgets are required for doses compatible with screen-printed metal pastes, to reach very good activation rates. However, if good sheet resistances and saturation current densities may be obtained, we met strong limitations of the implied open-circuit voltage of the n-type Czochralski silicon substrates, which is incompatible with high-efficiency solar cells. Such limitations are not encountered with beamline where pure B+ ions are implanted. Efforts on the passivation quality may improve the implied open-circuit voltage but are not sufficient. We provide experimental comparison between beamline and plasma immersion allowing us to discriminate the causes explaining this observation (implantation technique or ion specie used) and to infer our interpretation: The co-implantation of fluorine seems to indirectly impact the lifetime of the core substrate after thermal annealing. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Evolution of electrical properties and thin-film transistor characteristics of amorphous indium gallium zinc oxide (IGZO) thin films synthesized by RF sputtering with O2 plasma immersion has been examined. O2 plasma immersion results in an enhancement in the Hall mobility and a decrease in the electron concentration; and the transistor performance can be greatly improved by the O2 plasma immersion. X-ray photoelectron spectroscopy analysis indicates that the effect of O2 plasma immersion on the electrical properties and the transistor performance can be attributed to the reduction of the oxygen-related defects in the IGZO thin films. [Copyright &y& Elsevier]

Abstract: Core-shelled structures such as zinc oxide (ZnO) on carbon nanotubes (CNTs) give rise to interesting material properties. In this work, a triple-layered core–shell–shell structure is presented where the effects of fluorine (F) incorporation on the outmost shell of the ZnO-CNT structure are studied. The samples prepared ranged from a short 2min to a 30min immersion in carbon tetraflouride (CF4) plasma. In addition, its effects on the electron emission properties also studied and it is shown that the plasma immersions create thinner field emitters with sharp tiny wrinkles giving rise to more electron emission sites and higher enhancement factor. In addition, X-ray photoelectron spectroscopy measurements showed that F ions replace O in ZnO coatings during immersion process, thus increasing the electrical conductivity and shifts the Fermi level of ZnO upwards. Both physical and electronic effects further contribute to a lower threshold field. [Copyright &y& Elsevier]

Abstract: Multilayer silica/alumina films were created by plasma immersion implantation and deposition to protect against atomic oxygen (AO) in low earth orbit environment. The AO erosion mechanism of polyimide under multilayer silica/alumina films has been investigated using a ground-based AO simulator and Monte Carlo model. The results demonstrate that protective films are detached and plumped due to AO undercutting, and the exterior silica film is partly detached proven by chemical composition depth profile and erosion patterns. The undercutting model involving collision, diffusion, reaction, gas releasing, and retroaction on films is proposed. Based on the model, scattered impingement has serious erosion, although AO does not directly attack interior polymer. AO erosion predictions at two neighborhood cracks are first studied by Monte Carlo model for various incidence angles of AO. The protective film between cracks hinders the escape of AO, and accelerates the erosion. [Copyright &y& Elsevier]

Abstract: Ion implantation techniques have been used to improve surface properties for over more than four decades. Metallurgical application of ion beam techniques was first reported in the 70s by Harwell laboratory (UK), and by the Naval Research Laboratory (USA), mainly focused to nitrogen implantation of steels. From those first results to today ion implantation techniques have been introduced in many different applications for industrial sectors such as the aeronautical and biomedical. This paper presents some of the most important actual applications of ion implantation techniques. Different strategies of conventional Ion Implantation (II), Low energy-High Temperature Ion Implantation (LEHT), and Plasma Immersion Ion Implantation (PIII) are studied and compared in terms of modified surface properties and industrial application niches. Furthermore, the reported results show how these different treatments have a big potential for research in smart and nano-functional surfaces in applications including biomaterials and many other specific developments. [Copyright &y& Elsevier]

Abstract: CoCr alloys are widely used in some specific hip and knee prosthesis. In particular, they are used in advanced metal on metal (MoM) prostheses. However, while these new implants have an intermediate wear rate between low wear ceramic–metal and high wear polymer–metal prostheses, a high risk of metalosis produced by wear debris, originated in the metal–metal sliding contact, is still present. Oxygen plasma immersion ion implantation (PI3) provides a practical method to improve wear resistance of CoCr alloys, thus reducing the amount of wear particles. This paper describes the tribological and wear resistance improvements of CoCr alloy implanted by PI3. Friction and wear tests were performed to investigate the modifications obtained by oxygen implantation. Glow Discharge Optical Emission Spectrometry (GD-OES) analysis was employed to evaluate the oxide layer thickness and compositional changes of the metallic alloying elements produced by the oxygen treatment. Moreover, SEM analysis was carried out for detecting wear particles after ball on disk tests in a biological solution simulating the human body fluid. The reported results indicate that PI3 improves the wear resistance of CoCr alloy to be used in human body implants. [Copyright &y& Elsevier]

Kapton samples were implanted with aluminum in order to create a metal oxide layer for protection against atomic oxygen degradation in space environment. Three different approaches were used. First, an aluminum plasma was created by vacuum arc discharge in a magnetic field, and samples were implanted by plasma immersion. Although sample charging problems prevented implantation at significant depths, an ion mixing layer was formed, as shown by X-ray Photoelectron Spectroscopy (XPS) depth profile analysis, giving superior adhesion of the aluminum film to the substrate. In a second approach, a 20-nm aluminum film was deposited on a Kapton sample by electron beam, followed by nitrogen plasma immersion ion implantation. Rutherford Backscattering Spectroscopy (RBS) analysis did not show significant recoil implantation of aluminum, and the process resulted in a cracked film, possibly due to the formation of a stressed aluminum nitride layer. In a third approach, direct aluminum implantation by plasma immersion was made without a confining magnetic field. Charging problems are minimized in this low-density plasma, but an increase of a factor of 10 in treatment time was not enough to compensate the much lower dose implanted per pulse. This was revealed by oxygen degradation tests made by submitting the treated samples to RF oxygen plasmas and measuring the mass loss. The sample implanted in magnetically confined plasmas conserved its transparency and had negligible mass loss. Unconfined plasmas also resulted in a degradation protection layer but only in small patches of the substrate since the low dose and possibly a misalignment resulted in poor uniformity. Thermal transients followed by adhesion tests showed that direct implantation gives the necessary adhesion of the protective layer in order to withstand the harsh space environment. [Copyright &y& Elsevier]

In order to apply the protective effect of Cl doping for high-temperature oxidation resistance of TiAl alloys of complex-shaped parts, plasma immersion ion implantation (PI3) of chlorine into technical TiAl alloys was investigated. A specialized PI3 apparatus was optimized for the strongly etching electronegative Cl plasma. Plasma diagnostics was performed using a Langmuir probe. In order to sustain a sufficiently dense plasma, different RF antenna configurations are discussed and the resulting densities are compared. The influence of plasma pulsing on the surface interaction of Cl during the process was evaluated. Two different commercial alloys were implanted and tested. The resulting depth profiles of the modified surface layer were investigated using depth profiling with Auger electron spectroscopy (AES). After implantation, the Cl is located close to the surface. Oxidation tests at 900 °C in air for 100 h showed a strong decrease in oxidation, which is comparable to conventional beamline implantation of Cl. The effect is rather independent of the alloy composition. [Copyright &y& Elsevier]

Diamond-like-carbon has attracted much attention recently as a potential biomaterial in blood contacting biomedical devices. However, previous reports in this area have not adequately addressed the biocompatibility and acceptability of the materials in blood contacting applications. In this study, hydrogenated amorphous carbon (a-C:H) films were fabricated on silicon wafers (1 0 0) using plasma immersion ion implantation-deposition. A series of a-C:H films with different structures and chemical bonds were fabricated under different substrate voltages. The results indicate that film graphitization is promoted at higher substrate bias. The film deposited at a lower substrate bias of −75 V possesses better blood compatibility than the films at higher bias and stainless steel. Our results suggest two possible paths to improve the blood compatibility, suppression of the endogenic clotting system and reduction of platelet activation. [Copyright &y& Elsevier]

Implantation of oxygen in stainless steel (15% Cr) via plasma-based ion implantation in a distributed ECR plasma reactor has been studied as functions of ion energy and dose. Due to the formation at the surface of dielectric films with optical index and thickness depending on the implantation time and pulse voltage (up to 44 kV), various colorations can be obtained. The experimental results demonstrate the feasibility of uniform processing, the possibility of reaching perfect control of the coloring through the dose and energy of implanted ions, and that the resulting coloration varies monotonically when increasing the dose and penetration depth of implanted oxygen. Characterization of the films by scanning electron microscopy and X-ray microanalysis shows that oxygen implantation results in strong surface oxidation, but without any significant degradation of the surface aspect. The thickness and composition profiles of the oxide layers determined using X-ray photoelectron spectroscopy combined with ellipsometry indicate that the thickness, of course, increases with ion energy and dose, but that the composition of the oxide layer resulting from the implantation process is not uniform. A uniform iron oxide layer (with a stoichiometry closed to Fe2O3), free from chromium, is formed in the near-surface region, while chromium segregates at the interface between the oxide layer and the bulk stainless steel to form chromium oxide Cr2O3. [Copyright &y& Elsevier]

The lifetime of metallic components can be drastically increased by surface treatments ensuring a low friction coefficient, surface hardening and an anticorrosion coating. A promising method for such surface modifications is plasma-based ion implantation (PBII) of nitrogen. In order to improve and to obtain a better understanding of such a treatment, we have performed nitrogen implantation in different materials at various ion energy values using pure nitrogen and N2/H2 gas mixture plasmas. Fe and Ti samples were simultaneously treated in a large-volume PBII reactor in which the plasma is excited at the distributed electron cyclotron resonance. Si substrates were also implanted in order to characterize the nitrogen implantation efficiency by Fourier-transform infrared (FTIR) analysis. Profiles of the relative concentration of elements in the samples were deduced from X-ray photoelectron spectroscopy (XPS) analysis as a function of depth. The absolute concentration of implanted nitrogen was also obtained by nuclear reaction with 15N atoms implanted in metals via PBII from a 15N2/14N2 gas mixture. These results can be very useful for calibrating and improving PBII surface treatments of materials. [Copyright &y& Elsevier]

Silicon devices including diodes, metal oxide semiconductor capacitors, and p-channel metal oxide semiconductor transistors were fabricated by plasma immersion ion implantation (PHI) doping technique using a microwave multipolar bucket plasma system. BH diluted in helium (1%) was used as the gas source. The contamination by helium, hydrogen, iron, sodium, and aluminum impurities was evaluated by secondary ion mass spectrometry measurements. During PHI processing in an aluminum chamber with a stainless steel wafer holder, no aluminum and a dose of 4.1 x 10/cm of Fe were detected. Most of Fe ions were shielded by a thin layer of SiO during the device fabrications. Good quality devices have been demonstrated including low reverse current of 15 nA/cm (V = -5 V) in diodes and reasonable lifetimes of the minority carriers such as t = 55.0 µsec and = τ 54.2 µsec. [ABSTRACT FROM AUTHOR]

Abstract: Ion bombardment of biological cellular material has been used as a tool for the transfer of exogenous DNA macromolecules into the cell interior region. The precise physical mechanisms associated with this transfer of macromolecules through the cell envelope remain unexplained, however it has been observed that the ion bombardment is accompanied by the formation of “microcraters” on the wall of plant cells, and it is possible that these features provide channels for the macromolecule transfer. Thus the nature and origin of the microcraters are of importance to understanding the DNA transfer phenomenon as well as being of fundamental interest. We report here on the formation of microcraters on onion skin cell walls by plasma immersion ion implantation (PIII) using ~20keV Ar+ ions at a dose of about 1×1015 ions/cm2. The results indicate that PIII provides a tool for carrying out ion bombardment of living biological materials previously done using beam-line implantation methods. [Copyright &y& Elsevier]

Plasma-immersion doping, a technique more compatible with the processing of large-area glass substrates, is investigated as a replacement of ion implantation for incorporating fluorine in a zinc oxide thin film to improve the electrical characteristics of the corresponding thin-film transistors. Since the average energy of the ions in a plasma is lower than that of the ions used for implantation, less damage is induced in the channel of a transistor by the bombardment of the ions. Consequently, enhancement-mode transistors with a relatively high field-effect mobility of \sim\71\ \cm^2/\V\cdot\s, a lower drain leakage current, and improved reliability have been realized. [ABSTRACT FROM AUTHOR]