The ion implantation process is a very precise, controllable, and reproducible method used to enhance material properties of finished components such as ball bearings. Essentially, the target material is bombarded by accelerated ions to form a thin alloyed layer in the substrate. As the ions deposit their kinetic energy in the target it begins to heat up. To prevent thermal distortion in the finished pieces the ion implantation is performed at dose levels (dependent on the ion fluence and time duration of implantation) to insure that the target pieces stay at relatively low temperatures. Consequently, the low temperature requirement for many applications limits the economic, and probably, the physical success of ion implantation. The purpose of this study was to show the applicability of using a two-dimensional computer code developed to model plasma disruptions and subsequent energy deposition on a fusion reactor first wall to calculate surface and bulk temperature information during ion implantation. In turn the code may assist researchers pursuing development of adequate cooling for target materials in an attempt to overcome the low temperature constraint. All data supported the hypotheses that the two-dimensional code previously developed for fusion reactor applications was adequate to model the ion implantation process. / Graduation date: 1992

This thesis details the design and development of a solid-state, high power modulator for driving plasma ion implantation systems. A plurality of modulators can be stacked in a Marx geometry to allow complete voltage (implantation energy) scalability. Unlike a classic Marx modulator, the design employs actively controlled charging and discharging paths. This allows maximum modulation flexibility and efficiency. A hybrid Marx bank - pulse transformer configuration was commissioned in a 20keV 12A plasma ion implantation system for the purpose of photonics research. <p>The design portion of this work is accompanied by an investigation, extension and discretization of the Lieberman analytical model of plasma ion implantation dynamics. The model predicts final implantation concentrations as well as system operational limits in specific plasma conditions. A new extension to the model accounts for subtle time-of-flight effects on accelerating ions. Agreement between modeled and measured ion currents is good.<p>Finally, a collection of material processing experiments conducted with the plasma ion implantation system since its inauguration in February 2006 is briefly presented. In it, a new silicon-based light emitting diode is introduced.

This thesis describes the fabrication and testing of electroluminescent diodes made from silicon subjected to plasma ion implantation. A silicon-compatible, electrically driven light source is desired to increase the speed and efficiency of short-range data transfer in the communications and computing industries. As it is an indirect band gap material, ordinary silicon is too inefficient a light source to be useful for these applications. Past experiments have demonstrated that modifying the structural properties of the crystal can enhance its luminescence properties, and that light ion implantation is capable of achieving this effect. This research investigates the relationship between the ion implantation processing parameters, the post-implantation annealing temperature, and the observable electroluminescence from the resulting silicon diodes.<p> Prior to the creation of electroluminescent devices, much work was done to improve the efficiency and reliability of the fabrication procedure. A numerical algorithm was devised to analyze Langmuir probe data in order to improve estimates of implanted ion fluence. A new sweeping power supply to drive current to the probe was designed, built, and tested. A custom software package was developed to improve the speed and reliability of plasma ion implantation experiments, and another piece of software was made to facilitate the viewing and analysis of spectra measured from the finished silicon LEDs.<p> Several dozen silicon diodes were produced from wafers implanted with hydrogen, helium, and deuterium, using a variety of implanted ion doses and post-implantation annealing conditions. One additional device was fabricated out of unimplanted, unannealed silicon. Most devices, including the unimplanted device, were electroluminescent at visible wavelengths to some degree. The intensity and spectrum of light emission from each device were measured. The results suggest that the observed luminescence originated from the native oxide layer on the surface of the ion-implanted silicon, but that the intensity of luminescence could be enhanced with a carefully chosen ion implantation and annealing procedure.</p>

In this study, photoluminescence properties of as grown, Ge implanted GaSe and InSe crystals with doses 1013, 1014, and 1015 ions/cm2 and 1015 ions/cm2 Ge implanted and annealed GaSe and InSe single crystals grown by using 3-zone vertical Bridgman-Stockbarger system have been studied by photoluminescence spectroscopy (PL). PL spectra of as grown and implanted GaSe samples with three different doses have been studied in the ranges within the wavelength interval 570-850 nm and in the temperature ranges between 21 and 110 K. Temperature dependencies of all observed bands revealed that the peak with highest energy has excitonic origin and most of the others originate from donor-acceptor pair recombination. For GaSe samples implanted with 1013 and 1015 ions/cm2 Ge, PL spectra exhibited four emission bands while for as grown and the sample implanted with 1014 ions/cm2 v Ge had three bands. Variations of emission peaks were studied as a function of temperature. It was observed that centers of all bands shifted towards red continuously with temperature. The intensities of the emission peaks showed similarities with those obtained from as grown, 1013 and 1014 ions/cm2 Ge implanted GaSe while the peak intensities of the sample implanted with 1015 ions/cm2 Ge decreased with the temperature continuously. Using the temperature variation of the peak intensities and peak energy values activation energies were obtained and these results revealed that the two bands with low wavelength to be excitonic origin for the implanted samples with the doses 1013 and 1015 ions/cm2 Ge. Similar results were obtained for the implanted with 1015 ions/cm2 Ge and annealed sample. The other two peaks observed for these samples were attributed to donor acceptor pair transitions. In addition, direct band gaps were found to be 2.12 eV at 32 K for as grown, 2.121 eV at 25 K for 1013 ions/cm2 Ge implanted, 2.121 eV at 21 K for 1014 ions/cm2 Ge implanted, 2.124 eV at 33 K for 1015 ions/cm2 Ge implanted GaSe samples and lastly 2.113 eV at 28 K for 1015 ions/cm2 Ge implanted and annealed GaSe. PL spectra of as grown, 1013, 1014, 1015 ions/cm2 Ge implanted, and 1015 ion/cm2 Ge implanted and annealed InSe samples were also obtained at 20 K. Two broad bands were observed in the spectrum of all InSe crystals and considered to be due to impurity levels within the materials.

In diesem Report wird eine Niederenergie-Implantationskammer (NEI-Kammer) beschrieben, die im Forschungszentrum Rossendorf entwickelt und aufgebaut wurde. Die Kammer ermöglicht es, die Implantation von Ionen bei niedrigen Energien (< 30 keV) mit einer Implantationsanlage für mittlere Energien durchzuführen. In der Kammer werden der Ionenstrahl, den der Implanter liefert, auf die erwünschte niedrige Energie abgebremst. Dazu wird ein elektrostatisches Bremslinsensystem eingesetzt, das auf einem neuartigen Prinzip basiert. Das System besteht aus einer Sammellinse und einer Zerstreuungslinse, wobei die Öffnungsfehler beider Linsen entgegengesetzte Vorzeichen besitzen und sich gegenseitig kompensieren. Dadurch ist es möglich, Wafer gebräuchlicher Größe bei geringer Energie mit hoher Dosishomogenität zu implantieren. Die NEI-Kammer ist insbesondere für Forschungseinrichtungen eine vorteilhafte Lösung, da sie eine wesentlich kostengünstigere und flexiblere Alternative zur Anschaffung einer Niederenergie-Implantationsanlage darstellt.

Le carbure de silicium est un matériau envisagé pour le conditionnement du combustible dans les réacteurs de quatrième génération. Ce travail a pour objectif d'étudier la capacité de confinement des produits de fission et l'évolution de la structure de ce matériau sous les effets combinés de la température et du rayonnement. Les implantations d'ions de basse énergie et l'incorporation d'analogues stables de produits de fission (Cs et I) dans des monocristaux de 6H-SiC ont été réalisées sur l'implanteur ou l'accélérateur du CSNSM. Les irradiations avec des ions lourds de haute énergie ont été effectuées au GANIL. L'évolution du profil des ions implantés et de la structure du cristal a été étudiée par RBS et canalisation. Des informations complémentaires ont été apportées par la spectroscopie d'absorption UV-visible. Les implantations d'ions de basse énergie à température ambiante conduisent à l'endommagement rapide du cristal. Par contre, une élévation de la température d'implantation (600 °C) permet de conserver un faible taux de désordre dans le cristal. Les irradiations avec des ions lourds de haute énergie n'endommagent pas les cristaux de SiC mais au contraire, elles provoquent une guérison du désordre créé préalablement par l'implantation d'ions I de basse énergie. Ces marqueurs d'iode ne diffusent pas lors d'irradiations avec des ions lourds de basse ou de haute énergie à température ambiante ou à 600 °C. Cependant, une diffusion des ions Cs a été observée lors d'un recuit thermique post-implantation à 1300 °C, température à laquelle le cristal qui comportait une couche amorphe étendue commence à retrouver une structure monocristalline.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 97-108). Also available in print.

Polyetheretherketone (PEEK), a polymer with mechanical strength comparable to human bone, is gaining popularity in the orthopedic field because it can potentially relieve the clinical complications, such as stress shielding effect and inevitable implantation failure, which are caused by the mismatch of the mechanical strength between the current metallic implants and the implantation sites. However, it is bio-inert and requires supplementary modification. Plasma immersion ion implantation (PIII) has been well documented that it is a good way to improve the bioactivity of a biomaterial. It is a method that introduces new elements to the biomaterial, generating bio-functional groups on the material surface without altering its mechanical properties. Hence, the aim of this study is to improve the bioactivity of PEEK by modifying its surface chemistry with the use of water (H2O) and ammonia (NH3) plasma immersion ion implantation (PIII) without altering its mechanical properties. After PIII treatment, a series of surface characterization tests that provide information about the surface properties, such as surface energy, roughness, surface chemical composition and crystallinity of PIII-treated PEEK were carried out. Results show that both H2O PIII and NH3 PIII-treated PEEK had significantly higher surface energy and roughness than untreated PEEK. There was also no significant change in the crystallinity of the PIII-treated PEEK, indicating that PIII treatment will not alter the mechanical properties of PEEK. Improvement in wetting properties of PEEK samples suggest the formation of polar functional groups on the PIII-treated PEEK materials, while the increased in surface roughness may be due to the energetic bombardments of plasma ions on the material surface. The in vitro bioactivity of plasma-treated PEEK was investigated and confirmed with hMSC-TERT. Initial cell attachment, cell spreading area, cell proliferation and differentiation were studied. Cell adhesion and cell spreading were enhanced on PIII-treated PEEK, and higher cell viability was observed on PIII-treated PEEK. Moreover, cell proliferation was promoted on early time point and cell differentiation was also enhanced particularly on day 7 by measuring the alkaline phosphatase activity. Therefore, H2O-PIII and NH3-PIII treatments were able to promote the bioactivity of PEEK samples. / published_or_final_version / Orthopaedics and Traumatology / Master / Master of Philosophy

In the present work Mg and MgAl thin films were fabricated using physical vapour deposition (PVD) technologies as non-traditional and new nanotechnology methods for designing high performance hydrogen storage materials. The physical vapour deposition technologies allow the formation of metastable metal, alloy and chemical compounds with strictly controlled composition, microstructure and stoichiometry at low temperatures. The synthesis of MgH2, MgAl and Mg(AlH4)2 films has been conducted in two steps: (i) fabrication of thin films employing magnetron sputtering in Ar gas, and (ii) hydrogenation of thin films employing plasma immersion ion implantation technologies. For the first time, chemical compound Mg(AlH4)2 has been synthesized using the deposition of Mg and Al atoms from gas phase in hydrogen plasma (reactive deposition with simultaneously hydrogen implantation). The transformation of Mg thin film to MgH2 takes place at 400 K temperature during hydrogenation in hydrogen plasma. Experimental results showed that hydriding kinetics of Ti-doped Mg film increases and desorption temperature decreases by 60-80 K and the maximum H2-effusion from the Ti-undoped Mg-Al takes place at temperature 475 K, and for the Ti-doped Mg-Al film – at temperature 410 K; the release time of accommodated hydrogen is shorted for the Ti-doped Mg-Al film. The mathematical model of hydrogenation shows that during the process of material irradiation in plasma the concentration of incident ions in... [to full text] / Šiame darbe, panaudojant jonines-plazmines technologijas, sintezuotos Mg, MgH2, Mg-Al ir Mg(AlH4)2 plonos nanokristalinės dangos. Ištirta jų struktūros, paviršiaus morfologijos ir sudėties priklausomybė nuo nusodinimo ir hidrinimo plazmoje technologinių parametrų. Darbe panaudoti plėvelių formavimo metodai: (i) magnetroninis-joninis garinimas Ar dujų aplinkoje; (ii) plonų dangų prisotinimas vandeniliu, panaudojant vandenilio jonų implantacijos iš plazmos technologijas. Šio darbo originalumas susijęs su nepusiausvyrinių plazminių technologijų panaudojimu nanokristalinių medžiagų hidrinimui. Pirmą kartą atlikta metalų hidridų sintezė ir ištirta vandenilio kaupimosi kinetika nanostruktūrinėse medžiagose panaudojant plazminės vandenilio implantacijos technologiją. Gauti rezultatai patvirtina joninių-plazminių technologijų pranašumus, iš kurių svarbiausias - formuojamų plėvelių mikrostruktūros valdymas nanometriniame lygyje. Tyrimo metu, panaudojant vandenilio jonų implantaciją į Mg-Al dangas, pirmą kartą susintezuotas Mg(AlH4)2 hidridas. 5 storio Mg dangų transformacija į MgH2, hidrinimo procesą atliekant vandenilio plazmoje, įvyksta esant 400 K temperatūrai. Eksperimentiniai rezultatai atskleidė, kad Ti priemaišomis legiruotose Mg dangose paspartėja hidridų formavimosi kinetika, o vandenilio desorbcijos temperatūra sumažėja 60-80 K. Vandenilio desorbcijos kinetika Ti priemaišomis legiruotose Mg-Al dangose taip pat yra spartesnė, o jų desorbcijos temperatūra sumažėja 65 K... [toliau žr. visą tekstą]

The work described in this thesis is an analysis of the Plasma Source Ion Implantation (PSII) process. A metal target is placed within a plasma, and pulsed to a high negative potential (10 - 50 kV). The electrons in the plasma close to the target are then repelled very rapidly, leaving an area of uniform positive charge. This causes an electric field to be set up between the plasma and the metal target. The ions close to the target are then accelerated towards the target by the electric field. The ions reach the target at high velocities, and implant deeply into the metal (-5 x 10-8 m), and form nitrides, which pin dislocations within the metal's atomic structure. The strength of the metal is therefore increased, and other properties such as the corrosion resistance of the metal are also improved. Metals that have undergone the PSII process have widely diverse applications. For example, in the motor industry, ion implanted metal punches last much longer than nitrided punches, while in the medical industry ion implanted metals are used for artificial limbs. A combination of a number of different analytic, numerical and simulation models are used to describe the PSII process, including the plasma behaviour and final nitrogen implantation profile in the metal target after the application of the voltage pulse. In all cases, a specific attempt has been made to realistically describe as closely as possible, the actual experimental arrangement at the University of Natal. For example: a waveform with a fast rise time, short plateau and exponential decay was used; the nitrogen plasma was more realistically described by a two species fluid to account for the measured N+, N; mix; and finally, the actual atomic composition for 304 stainless steel was used in the TAMIX particle simulation. This work thus models the whole PSII process, and could form the basis of future studies for the optimisation of the process. / Thesis (M.Sc.)-University of Natal, 1993.