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Hydrogen storage is a key enabling technology for the extensive use of hydrogen as energy carrier. This is particularly true in the widespread introduction of hydrogen in car transportation. Indeed, one of the greatest technological barriers for such development is an efficient and safe storage method. So, in this tutorial review the existing hydrogen storage technologies are described with a special emphasis on hydrogen storage in hydrogen cars: the current and the ongoing solutions. A particular focus is given on solid storage and some of the recent advances on plasma hydrogen ion implantation, which should allow not only the preparation of metal hydrides, but also the imagination of a new refluing circuit. From hydrogen discovery to its use as an energy vector in cars, this review wants to be as exhaustive as possible, introducing the basics of hydrogen storage, and discussing the experimental practicalities of car hydrogen fuel. It wants to serve as a guide for anyone wanting to undertake such a technology and to equip the reader with an advanced knowledge on hydrogen storage and hydrogen storage in hydrogen cars to stimulate further researches and yet more innovative applications for this highly interesting field.

Hydrogen storage is a key enabling technology for the extensive use of hydrogen as energy carrier. This is particularly true in the widespread introduction of hydrogen in car transportation. Indeed, one of the greatest technological barriers for such development is an efficient and safe storage method. So, in this tutorial review the existing hydrogen storage technologies are described with a special emphasis on hydrogen storage in hydrogen cars: the current and the ongoing solutions. A particular focus is given on solid storage and some of the recent advances on plasma hydrogen ion implantation, which should allow not only the preparation of metal hydrides, but also the imagination of a new refluing circuit. From hydrogen discovery to its use as an energy vector in cars, this review wants to be as exhaustive as possible, introducing the basics of hydrogen storage, and discussing the experimental practicalities of car hydrogen fuel. It wants to serve as a guide for anyone wanting to undertake such a technology and to equip the reader with an advanced knowledge on hydrogen storage and hydrogen storage in hydrogen cars to stimulate further researches and yet more innovative applications for this highly interesting field. [ABSTRACT FROM AUTHOR]

The goal of this work was to study nitrogen implantation from plasma with the aim of applying it in dual gate oxide technology and to examine the influence of the rf power of plasma and that of oxidation type. The obtained structures were examined by means of ellipsometry, SIMS and electrical characterization methods.

Experiments presented in this work are a summary of the study that examines the possibility of fabrication of oxynitride layers for Si structures by nitrogen implantation from rf plasma only or nitrogen implantation from rf plasma followed immediately by plasma oxidation process. The obtained layers were characterized by means of: ellipsometry, XPS and ULE-SIMS. The results of electrical characterization of NMOS Al-gate test structures fabricated with the investigated layers used as gate dielectric, are also discussed.

Compared with traditional impact-resistant materials, nanocarbon materials have the advantages such as light weight, large specific volume for energy dissipation and their exceptional thermal stability for the extreme-environmental working potentials. However, based on the commonly used fabrication method, the general nanocarbon structures (e.g. carbon nanotube (CNT) array) are always constructed with the weak interaction between units. Therefore, when they are subjected to impact, the impact energy cannot be transferred throughout the whole loose and discontinuous structure efficiently, which results in the degradation of their impact-resistant capabilities. To address the above issue, we fabricated a nanocarbon "cushion" with the combination of a diamond like carbon (DLC) film and multi-wall CNT (MWCNT) array. The DLC film was deposited successfully onto the as-grown MWCNT array through enhanced glow discharge plasma immersion ion implantation and deposition (EGD-PIII&D) method to form a continuous upper layer which is vital to distribute and transfer the impact energy loading. The new nanocarbon system has high specific dissipated energy up to ∼2.22 kJ/m3, which is almost twice as much as that of the commercial polyurethane sponge. We anticipate that this study will provide new insights to develop novel nanocarbon materials for impact resistance in high-tech edge applications. Image 1 • A nanocarbon "cushion" by combining a diamond like carbon film and a multi-wall CNT array was firstly reported. • The structure design of nanocarbon cushions enables the release of impact energy throughout the whole material. • The specific dissipated energy of nanocarbon cushions is about 2-fold higher than that of commercial polyurethane sponges. • The nanocarbon cushions are promising to address the protective issues in the specific high-tech fields. [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]

We report normally off AlGaN/GaN high-electron mobility transistors realized by using the thin and high Al composition barrier design in conjunction with O2 plasma implantation. The AlGaN barrier layer under the gate is selectively treated by low-energy O2 plasma in order to positively shift the threshold voltage of devices. The obtained enhancement-mode HEMT exhibits a threshold voltage ( VTH) of +1 V, a high peak transconductance of ∼230 mS mm−1, and a maximum drain current of 424 mA mm−1 at a gate bias of 3 V for a gate length of 0.6 µm. A suppressed gate reverse leakage current and a high breakdown voltage of 450 V are achieved. Moreover, gradually partial oxidation of AlGaN barrier layer is determined to be responsible for the plasma-induced VTH modulation effect through a systematic investigation. The results indicate O2 plasma implantation can be a promising method for fabrication of enhancement-mode GaN-based devices. [ABSTRACT FROM AUTHOR]

Abstract: Surface modification of biomaterials by conventional ion implantation (II) and plasma immersion ion implantation (PI3) are innovative methods to improve the biocompatibility of these advanced materials. This paper describes the biocompatibility improvements of Ti6Al4V and Co28Cr6Mo implanted with N and O in a conventional implantation and a plasma immersion ion implantation processes. Tribo-corrosion friction and wear tests were performed in a realistic environment – in Hank’s solution – to investigate the introduced modifications. The wear performance was only slightly improved due to a thin layer thickness, whereas, in contrast, the corrosion rate was significantly reduced. [Copyright &y& Elsevier]

High-energy plasma immersion ion implantation (PIII) in the range of 50-100 keV is an interesting alternative of surface modification technique to more commonly investigated beam processing of materials in such energies. A stacked Blumlein (SB) technique was used to reach high-voltage pulses of 30 to 100 kV, with much cheaper and electronically simpler configuration compared to a hard-tube (HT) system previously used by another PIII group. The reason is because Blumlein systems employ cheaper thyratrons with higher current capabilities compared to HT tetrodes. Although HT modulators provide higher retained peak dose and variable pulse duration, Blumlein pulsers are preferable for low-cost systems with lower dose and high-energy implantation. The disadvantages of Blumlein systems are their fixed pulse duration and lower repetition rate (<300 Hz) during operation regime. In this paper, PIII results obtained for SB operations between 50 and 75 kV will be discussed using an improved vacuum system and a proper high-voltage feed-through of 75 kV. High-energy (up to 75 keV) short (1.2 µs) repetitive (100 Hz) pulses were delivered to produce the plasma and carry out nitrogen ion implantation in the high-voltage glow-discharge mode. Al7475, Al5052, Ti6Al4V alloys, and ultrahigh-molecular-weight polyethylene polymer are materials of great interest to the aerospace field which are being treated by this high-energy PIII technique. [ABSTRACT FROM AUTHOR]

A new method was developed to produce lithium plasma for plasma immersion ion implantation. Initially, an argon glow discharge with operation pressure ranging from 2 × 10-1 to 1 mbar is generated by negatively polarizing an electrode from -400 to -1500 V. Small pieces of metallic lithium that are 99.9% pure fill the top of a conic crucible, with a depth of 2 cm, in electric contact with the electrode. Argon ions from the plasma are used to bombard this target, where heat is created by the momentum transfer from the impacting ions to the crucible. By controlling the operation pressure and the electrode voltage polarization, it is possible to easily heat the crucible to temperatures above the lithium melting point (180 °C), causing its evaporation. Lithium atoms are then ionized, mainly due to collisions, with argon ions moving toward the crucible. Double Langmuir probe measurements indicated variation in the density of the discharge from 4 × 109 cm-3 to 1010 cm-3 after lithium evaporation. Silicon wafer pieces immersed in this mixed plasma were submitted to repetitive negative high-voltage pulses (3 kV/6 μs/2.5 kHz) to accelerate plasma ions. High strain in the treated layers was measured by high-resolution X-ray diffraction. Photoluminescence intensity increased after annealing. X-ray photoelectron spectrometry measurement revealed lithium implantation in silicon with an atomic concentration of 78% on the top surface and a penetration depth of about 75 nm. [ABSTRACT FROM AUTHOR]

Abstract: The study examines the possibility of fabrication of pedestal oxynitride layers for high-k gate stacks by means of nitrogen implantation from r.f. plasma alone or followed immediately by the plasma oxidation process. The obtained layers were characterized by means of ellipsometry, X-ray photoelectron spectroscopy (XPS) and ultra low energy secondary ion mass spectrometry (ULE-SIMS). The results of electrical characterization of NMOS Al-gate test structures fabricated with the investigated layers used as a gate dielectric are also discussed. Presented results seem to be very promising and presented methods allow to form ultrathin pedestal oxynitride layers with good properties (e.g. breakdown behavior) and we believe that presented method—ultrashallow nitrogen plasma implantation with plasma oxidation may be seriously considered for future VLSI technologies. [Copyright &y& Elsevier]

Abstract: In mixed logic/memory circuits manufactured as a system on chip, two different thicknesses of dielectric layers are required. Simultaneous formation of both layers is possible if oxidation of a silicon layer is preceded by local nitrogen implantation, since the rate of oxidation depends on the nitrogen implantation dose and its profile. Experiments presented in this work show a possibility and an attempt of practical realization of controlling a very thin dielectric layer''s thickness by preceding the oxidation with an ultra-shallow nitrogen implantation from r.f. plasma. As opposed to the methods presented in the literature so far, where classical implanters or the ion immersion implantation plasma (IIIP) technique were used for ultra-shallow implantation, our process is performed in a typical PECVD planar plasma reactor. The r.f. plasma nitrogen implantation has been carried out from NH3 plasma and then immediately followed by the thermal- or plasma-oxidation process. The electrophysical properties of the obtained layers and systems (ultrathin dielectric layer, silicon) were characterized by electrical methods. Results of ellipsometric, XPS and ULE-SIMS measurements are also presented and discussed. [Copyright &y& Elsevier]

Experiments presented in this work are a summary of the study that examines the possibility of fabrication of oxynitride layers for Si structures by nitrogen implantation from rf plasma only or nitrogen implantation from rf plasma followed immediately by plasma oxidation process. The obtained layers were characterized by means of: ellipsometry, XPS and ULE-SIMS. The results of electrical characterization of NMOS Al-gate test structures fabricated with the investigated layers used as gate dielectric, are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Plasma surface modification has become a popular method to modify the surface structure and biological properties of biomaterials. By modifying selective surface mechanical and biological properties, conventional materials can be redesigned with their favorable bulk attributes retained. Plasma surface modification can enhance the multi-functionality, mechanical properties, as well as biocompatibility of artificial biomaterials and medical implants. Here, our recent research work on plasma modification of orthopedic materials including titanium and nickel–titanium shape memory alloys as well as diamond-like carbon as cardiovascular materials is described. NiTi alloys that possess shape memory and super-elastic properties are of interest in spinal deformity correction. Shape recovery inside the human body allows for less traumatic gradual correction while obviating the needs for multiple surgeries. However, leaching of harmful nickel ions from the materials causes health hazards and plasma implantation is an excellent means to create a graded barrier layer to impede Ni out-diffusion and improve the corrosion resistance. Our latest results demonstrate that the shape recovery property is not compromised with the plasma treatment. Also described are our results on titanium implanted with calcium and sodium for enhancement of the surface biological properties. With regard to cardiovascular materials, the two main requirements are good surface mechanical properties and blood compatibility. Diamond-like carbon (DLC) is a potential material in artificial heart valve and our recent studies suggest that doping DLC with biological friendly elements such as nitrogen and phosphorus can improve the blood compatibility of the materials. [Copyright &y& Elsevier]

A high-voltage pulsed power supply of 100 kV/200 A with output short pulses of the order of 1 μs (based on stacked coaxial Blumlein technology) was developed for use in surface treatment of materials by plasma implantation. The plasma implantation process requires pulse repetition and the authors' device is capable of operating at a frequency range of 10-150 Hz, depending on the level of the output voltage. Herein, the authors show that nitrogen-ion species were implanted into stainless steel surfaces (SS304) at high energies (> 30 keV) by using this pulser, inducing α phase as demonstrated by X-ray diffraction diagnostic. Moreover, microhardness tests of these treated samples have shown an improvement of about 13.0% for the surface hardness factor. [ABSTRACT FROM AUTHOR]

Abstract: The main objective of this paper is to describe the use of a high voltage pulser based on Blumlein technology for surface treatment by plasma immersion implantation. In particular, we will consider its potential application for nitriding polymer and Al surfaces. The Blumlein technique consists basically of charging several coaxial transmission in parallel and discharging them in series into a matched load by means of the closure of a thyratron switch at the generator input side. [Copyright &y& Elsevier]

Abstract: Plasma immersion ion implantation and deposition (PIII&D) is an effective technique to enhance the surface bioactivity of materials. In this paper, recent progress made in our laboratory on plasma surface modification of biomedical materials is described. NiTi alloys have unique super-elastic and shape memory properties and are suitable for orthopedic implants but the leaching of toxic Ni may pose health hazards in humans. We have recently investigated the use of acetylene, oxygen and nitrogen PIII&D to prevent out-diffusion of nickel and good results have been obtained. Silicon is the most important material in the microelectronics industry but its surface biocompatibility has not been investigated in details. We have recently performed hydrogen PIII into silicon to improve the surface bioactivity and observed biomimetic growth of apatite on the surface in simulated body fluids. Diamond-like carbon (DLC) is widely used in the industry due to its excellent mechanical properties and chemical inertness and by incorporation of elements such as nitrogen and phosphorus, the surface blood compatibility can be improved. The properties as well as in vitro biological test results are discussed in this article. [Copyright &y& Elsevier]

Abstract: A ternary barrier film TiSiN was prepared by low frequency, high density inductively coupled plasma (ICP) implantation of N into TiSi substrate. This leads to the formation of Ti–N and Si–N compounds in the ternary film. Using this technique, 5–20-nm-thick TiSiN films were successfully grown over different deposition conditions including external bias, argon gas flow rate and nitrogen plasma treatment time. Barrier film structure was characterized by X-ray diffraction (XRD). For compositional analysis, X-ray photoelectron spectroscopy was used. The diffusion study was carried out by depth profiling of Cu using time-of-flight secondary ion mass spectrometer (ToF-SIMS) after annealing treatment at various temperatures. Discussion on the relationship between the barrier performance and the film structures is made in an attempt to elucidate the controlling factor for Cu diffusion in such a mixed microstructure. The implication to process conditions is also discussed. [Copyright &y& Elsevier]

Plasma immersion ion implantation (PIII) is a relatively complex process. Utilizing plasma and TRIM simulation, plasma implanted nitrogen depth profiles in iron are simulated in this work. Many factors such as the high voltage pulse rise time, voltage amplitude, pulse duration, plasma composition, etc. have a critical influence on this depth profiles. Our results confirm the broader distribution as well as shift of the implant peak toward the surface. Compared to the pulse duration and plasma composition, the rise time of the high voltage pulse has a more predominant effect on the shape of the profile. At higher implantation voltage, the nitrogen profile resembles that of multiple energy implantation in the beam-line mode. From this perspective, broadening of the ion energy spectrum in PIII is favorable since a single process can achieve the results of multiple energy ion implantation. This is particularly useful for processes such as shallow junction formation in microelectronics. [Copyright &y& Elsevier]

Plasma immersion ion implantation (PIII) was originally conceived as a method for high-flux implantation and with the capability of conformally implanting non-planar surfaces. Research in the last 15 years has revealed other characteristics which are dissimilar with beamline implantation: multiple species implant; energy and angular distribution spread; plasma/surface interaction; substrate self-heating; and dielectric substrate charging. This paper will address the effect of sheath characteristics, conformality of implant, multiple species implant, ion-neutral scattering and bias schemes on designing the processing recipes. [Copyright &y& Elsevier]

Plasma immersion ion implantation (PIII) offers high throughput and efficiency in the synthesis of silicon-on-insulator (SOI) materials. In the separation by plasma implantation of oxygen (SPIMOX) process, the spatial and time variation of the sample temperature must be known and well controlled to ensure uniform buried oxide and silicon overlying layer thicknesses over the entire silicon wafer. In this paper, we describe a two-dimensional model and derive the temperature distribution on the silicon wafer with respect to time and other process parameters. Our results show laterally nonuniform heating by the incoming ions and the local temperature is influenced more by the sample voltage and thermal irradiation coefficient of the target than the pulse duration and plasma density. The model provides a simple and quick means to determine whether external heating will be needed to maintain the sample temperature at 600°C during the SPIMOX process [ABSTRACT FROM PUBLISHER]

Abstract: Magnesium films were magnetron sputter deposited on AISI 316L stainless steel and hydrogenated at 450K by the plasma immersion ion implantation technique using CH4 +Ar gases under a pressure of 10Pa. The goal was to obtain hydrogen separation and formation of hydrides in Mg film thus avoiding a hydrogen gas purification process. The depth profiles of C and H atoms across the Mg film were analyzed by the Nuclear Reaction Analysis and secondary ion mass spectrometry. After 0.5h of plasma treatment with a 1kV bias voltage, C atoms remained in the near surface region while H atoms were homogeneously distributed across the entire film thickness. The results are explained on the basis of C and H ion implantation and atomic transport kinetics along the grain boundaries of a nanocrystalline Mg film. [Copyright &y& Elsevier]