Due to the fast expansion and development in the optical communication industry, the demand for the film quality has correspondingly increased. Ion beam sputter deposition (IBSD) achieves the lowest loss, but low throughput. In our Lab., E-beam system was used for CaO, MgO and Cr2O3 evaporation on the circumference of the Cr:YAG crystal fiber. Although the substrate was heated to around 275oC, the thin film didn¡¦t achieve low loss and high laser-induced damage threshold film. Adding ion-beam assisted deposition (IAD) system to enhance the thin film energy and packing density is the main theme of this thesis. The thesis mainly focuses on the characteristics of TiO2 and SiO2 thin film based on E-beam with IAD system. Spectrometer analyzer and Macleod software were used to calculate the refractive index and extinction coefficient. ESCA (electron spectroscopy for chemical analyzer) was adopt to measure the thin film composition of Ti, Si, O. SEM (scanning electron microscope) was used to observe the thin film quality. Low loss and high laser-induced damage threshold thin film are the goal of the present research. With optimized parameters, the refractive index of TiO2 film was achieved to be 2.51 at 500 nm, and the extinction coefficient was less than 2x10-4. The refractive index of SiO2 film can be achieved to be 1.466 at 500 nm, and the extinction coefficient was less than 1x10-4. An HR (R>99.83%) coating at 1233 nm was successfully demonstrated by the IAD deposition system.

Gloveboxes, where special nuclear material is handled and such as those present at Los Alamos National Labs, LANL, provide an experimental area confined within a protective shell and with strict environmental controls. These gloveboxes allow workers to indirectly interact with hazardous material. Unfortunately, these gloveboxes are not fail proof and are subject to occasional accidental failures resulting in possible breaches of containment and release of nuclear material. In particular, fires within the gloveboxes are of major concern with regard to the potential for breaches and damage to not only the glovebox but also to surrounding areas as well. Another, potentially even catastrophic, result of glovebox fires is the potential for the spread of radioactive contamination. There is some historical precedent of contaminant release resulting from glovebox fires, such as those at the Rocky Flats Plant (Buffer, 2012). Gloveboxes at LANL are currently equipped with manually activated fire suppression systems. In the event of an incident, a worker would hit a nearby emergency button and the system would be activated. However, this method relies on the worker to have the presence of mind in the face of danger to activate the system, and as such there is no true guarantee that the systems will be triggered. Since the level of consequence is dire, then the ideal situation requires that other fire suppression systems be present which do not rely on human interaction to function. The Fire Foe™ system has been chosen as a secondary failsafe measure in order to meet this need. Analysis of how the casing of the Fire Foe™ system, composed of nylon 6,6 polymer, weathers under irradiation in gloveboxes is paramount in determining the effectiveness and potential lifetimes of the systems within the gloveboxes. Samples of nylon 6,6 were exposed to a 5 Ci PuBe neutron source located at the University of Texas as well as a high dose rate beam of 4.5 MeV alpha particles located at Los Alamos to determine the effect of neutron and alpha particle damage on the polymer material. Subsequent mechanical testing was conducted to determine alteration to the tensile properties of the nylon 6,6 material for both irradiated and non-irradiated samples. / text

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 198-208). Also available via the Internet.

Orientadores: Jacobus Willibrordus Swart, Stanislav Moshkalev / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T05:10:33Z (GMT). No. of bitstreams: 1 Silva_MarceloMacchida_M.pdf: 6148337 bytes, checksum: d4ca724ac84a5417bdd4995685227913 (MD5) Previous issue date: 2007 / Resumo: A nanotecnologia e uma área nova e promissora que englobam muitas disciplinas de ciência e engenharia. Seu rápido crescimento nas ultimas duas décadas é devido ao crescimento simultâneo na fabricação e caracterização de materiais em escala nanométrica. O objetivo deste trabalho é desenvolver uma técnica de processo híbrido para a fabricação de micro e nanocontatos assim como sua caracterização elétrica. Esse processo híbrido combina a fotolitografia seguida da técnica de lift-off e a deposição de platina por FIB. Para determinar a resistividade da platina depositada por FIB (Focuded Ion Beam), foram fabricas estruturas quadradas variando sua espessura de 5 nm - 100 nm e sua área 150 µm 150 µm e 20 µm x 20 µm. Resistores com comprimento de 30 µm variando sua área de secção (50 nm x 50 nm - 1 µm x 1 µm) foram fabricados a fim de uma melhor na caracterização do processo de deposição do filme de Pt assim como sua caracterização elétrica. As medidas elétricas foram realizadas na estação Keythley 4200 SCS, onde foi utilizado o método de quatro pontas nas estruturas quadradas para a caracterização da resistividade. Nos resistores utilizamos a configuração de dois terminais para a caracterização de resistência dos nanocontatos. / Abstract: Nanoscale science and technology is a young and burgeoning field that encompasses nearly every discipline of science and engineering, the rapid growth of the field in the past decades has been enable by the sustained advances in the fabrication and characterization of materials. This work presents the hybrid process for fabrication of micro and nanocontacts, this process include the lift - off technique and platinum deposited by FIB. For measurements, two types of test structures were fabricated: (i) 150 x 150 µm and 20 x 20 µm squares with thickness of 5, 10, 30 and 100 nm, and (ii) 30 µm long resistors with variable cross - section (50 nm x 50 nm to 1 µm x 1 µm). The Pt film resistivity has been measured by a four points probe method. / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16847号 / 工博第3568号 / 新制||工||1539(附属図書館) / 29522 / 京都大学大学院工学研究科原子核工学専攻 / (主査)教授 伊藤 秋男, 准教授 柴田 裕実, 准教授 松尾 二郎 / 学位規則第4条第1項該当

The search for alternative methods of synthesizing cubic boron nitride (cBN), one of the hardest known materials, at low thermo-baric conditions has stimulated considerable research interest due to its great potential for numerous practical industrial applications. The practical applications are motivated by the material’s amazing combination of extraordinarily superior properties. The cBN phase is presently being synthesized from graphite-like boron nitride modifications at high thermo-baric conditions in the presence of catalytic solvents or by ion–beam assisted (chemical and physical) deposition methods. However, the potential and performance of cBN have not been fully realized largely due to central problems arising from the aforementioned synthesis methods. The work reported in this dissertation is inspired by the extensive theoretical investigation of the influence of defects in a ecting the transformation of the hexagonal boron nitride (hBN) phase to the cBN phase that was carried out by Mosuang and Lowther (Phys Rev B 66, 014112 (2002)). From their investigation, using an ab-initio local density approach, for the B, C, N, and O simple defects in hBN, they concluded that the defects introduced into hBN could facilitate a low activation–energy hexagonal-to-cubic boron nitride phase transformation, under less extreme conditions. We use ion implantation as a technique of choice for introducing ‘controlled’ defects into the hot–pressed polycrystalline 99.9% hBN powder samples. The reasons are that the technique is non–equilibrium (not influenced by dilusion laws) and controllable, that is the species of ions, their energy and number introduced per unit area can be changed and monitored easily. We investigate the structural modifications of hBN by ion implantation. Emphasis is given to the possibilities of influencing a low activation–energy hBN-to-cBN phase transformation. The characterization of the structural modifications induced to the hBN samples by implanting with He+ ions of energies ranging between 200 keV and 1.2 MeV, at fluences of up to 1.0 1017 ionscm2, was accomplished by correlating results from X-Ray Di raction (XRD), micro-Raman (-Raman) spectroscopy measurements, and two-dimensional X-Y Raman (2D-Raman) mapping measurements. The surface to pography of the samples was investigated using Scanning Electron Microscopy (SEM). E orts to use Surface Brillouin Scattering (SBS) were hampered by the transparency of the samples to the laser light as well as the large degree of surface roughness. All the implantations were carried out at room temperature under high vacuum. 2D-Raman mapping and -Raman spectroscopy measurements done before and after He+ ion irradiation show that an induced hBN-to-cBN phase transformation is possible: nanocrystals of cBN have been observed to have nucleated as a consequence of ion implantation,the extent of which is dictated by the fluences of implantation. The deviationof the measured spectra from the Raman spectra of single crystal cBN is expected, has been observed before and been attributed to phonon confinement e ects. Also observed are phase transformations from the pre-existing hBN modification to: (a) the amorphous boron nitride (aBN), (b) the rhombohedral boron nitride (rBN) modifications, (c) crystalline and amorphous boron clusters, which are a result of the agglomeration of elementary boron during and immediately after ion implantation. These transformations were observed at high energies. Unfortunately, the XRD measurements carried out could not complement the Raman spectroscopy outcomes probably because the respective amounts of the transformed materials were well below the detection limit of the instrument used in the former case.

In this work, we have utilized an ion beam process known as gettering to migrate implanted Ni ions much deeper into the bulk substrate than their initial projected end of the range. The projected mean depth is known as Rp. The gettering effect is the most crucial part of the fabrication and we have found that for an H fluence of 3x 1016 cm-2 there is a threshold fluence of approximately 7.5 x 1015 cm-2 that cannot be surpassed if the gettering process is to be completed along with the substrate recovered to the high crystalline quality. This hard threshold is due to the gettering process relaxation induced mechanism that is responsible for migrating the Ni to the Rp/2 location while the H is vacating during the thermal annealing process. If the total number of vacancies produced by the H dissociation is not substantially larger than the total number of implanted Ni atoms the Ni will migrate to the Rp location of the Ni implantation at the amorphous and crystalline interface and toward the surface. When the gettering condition is not met the resulting magnetic responses vary from an exceptionally weak ferromagnetic response to not exhibiting a magnetic response. Additionally, conducting the ion implantation at an elevated substrate temperature does not increase the threshold Ni fluence above our established limit. During the elevated substrate temperature implantation, the hydrogen ions diffuse out to the surface resulting in less migration of the Ni to the initial Rp location within the Ni implantation region. The elevated temperature implantation condition appears to not create a sharp amorphous crystalline interface at the end of the range for the Ni implantation.

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No description available.

To investigate the ultimate resolution in ion beam lithography (IBL) the resist material poly(methyl methacrylate) PMMA has been modified by single ion impacts. The latent damage tracks have been etched prior to imaging and characterisation. The interest in IBL comes from a unique advantage over more traditional electron beam or optical lithography. An ion with energy of the order of 1 MeV per nucleon evenly deposits its energy over a long range in a straight latent damage path. This gives IBL the ability to create high aspect ratio structures with a resolution in the order of 10 nm. Precise ion counting into a spin coated PMMA film on top of an active substrate enabled control over the exact fluence delivered to the PMMA from homogenously irradiated areas down to separated single ion tracks. Using the homogenous areas it was possible to macroscopically measure the sensitivity of the PMMA as a function of the developing parameters. Separated single ion tracks wer e created in the PMMA using 8 MeV F, 71 MeV Cu and 88 MeV I ions. These ion tracks were etched to create voids in the PMMA film. For characterisation the tracks were imaged primarily with atomic force microscopy (AFM) and also with scanning electron microscopy (SEM). The series of studies presented here show that the sensitivity of the resist-developer combination can be tailored to allow the etching of specific single ion tracks. With the ability to etch only the damage track, and not the bulk material, one may experimentally characterise the damage track of any chosen ion. This offers the scientific community a useful tool in the study and fabrication of etched ion tracks. Finally work has been conducted to allow the precise locating of an ion beam using a nanoscale mask and piezoelectrically driven scanning stage. This method of beam locating has been trailed in conjunction with single ion detection in an effort to test the practical limits of ion beam lithography in the single ion realm.