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1
Westbrook, Owen William. "Crater ice deposits near the south pole of Mars." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53113.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2009.Includes bibliographical references (p. 55-60).
Layered deposits atop both Martian poles are thought to preserve a record of past climatic conditions in up to three km of water ice and dust. Just beyond the extent of these south polar layered deposits (SPLD), dozens of impact craters contain large mounds of fill material with distinct similarities to the main layered deposits. Previously identified as outliers of the main SPLD, these deposits could offer clues to the climatic history of the Martian south polar region. We extend previous studies of these features by cataloging all crater deposits found near the south pole and quantifying the physical parameters of both the deposits and their host craters. Using MOLA topography data, MOC and THEMIS imagery, and SHARAD radar sounding data, we characterize the distribution, morphology, and structure of the deposits. In addition, we examine the effect of the crater microenvironment on the formation and persistence of these deposits, exploring the relative importance of solar and eolian processes in shaping their present-day distribution and appearance. We consider the possibility that crater sand dunes may have promoted ice accumulation over time and weigh various explanations for the origins and larger climatic significance of these features.
by Own William Westbrook.
S.M.
2
Tong, Lege. "Material selection for a dry atmospheric mercury deposits sampler, an integrated chemical and statistical approach." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ35859.pdf.
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Lin, Zhi-Qing. "Trace metal contamination in forests of southern Quebec and pathway studies of airborne metal deposits." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40177.
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Trace metal contamination of the air-soil-tree system was examined in southern Quebec, where acid deposition and tree dieback have been recorded in high elevation forests. Mn pollution was emphasized due to its large emission from gasoline combustion in Canada. Airborne Cu, Mn, V, and Zn showed higher concentrations than those reported for other remote locations. Significant fluctuation in Mn concentrations during the winter-spring season was explored by air mass back trajectory analysis. The study suggested that high Mn concentrations resulted from the atmospheric long-range transport from Canadian industrialized and metropolitan regions. Metal concentrations in podzolic topsoils were generally higher than their world-wide average values. Concentrations of trace metals in balsam fir (Abies balsamea (L.) Mill) needles were below their suggested potential phytotoxic levels, except for Mn, which also increased with elevation. The scanning of needles with micro-PIXE showed no significant correlation between metal accumulation and epistomatal distribution on foliar surfaces.Pathways of trace metals deposited in the soil-tree system were elucidated through application of $ sp{54}$Mn and $ sp{65}$Zn on shoot, bark, and soil surfaces in growth-chamber experiments with balsam fir seedlings. Uptake and accumulation by seedlings 70 days after application on the shoot surface was about 25-30% of the remaining activities for $ sp{54}$Mn and $ sp{65}$Zn. Less than 1% of absorbed isotopes was translocated from the bark surface to other plant organs, whereas more than 50% of the radioisotopes absorbed at the shoot moved to the rest of the seedling. Acidic wetness facilitated the metal absorption through tree surfaces. Downward movement of the radioisotopes in podzolic soils was documented, and accumulation in seedlings by root uptake was 5% of the remaining activity for $ sp{54}$Mn and 3% for $ sp{65}$Zn 70 days after application. No appreciable elemental migration from internal tissues to epicuticular wax layers was found, and the leaching ratio was below 0.5 and 1.0% for $ sp{54}$Mn and $ sp{65}$Zn, respectively. This study helps to understand the links between atmospheric deposition and the elevated levels of Mn in trees, and potential effects of acid deposition on the bioaccumulation of toxic metal pollutants in high elevation forests in southern Quebec.
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Craddock, Paul R. "Geochemical tracers of processes affecting the formation of seafloor hydrothermal fluids and deposits in the Manus back-arc basin." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/55328.
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Thesis (Ph. D.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009.Includes bibliographical references.
Systematic differences in trace element compositions (rare earth element (REE), heavy metal, metalloid concentrations) of seafloor vent fluids and related deposits from hydrothermal systems in the Manus back-arc basin (Eastern Manus Basin, EMB and Manus Spreading Center, MSC) are used to investigate processes that affect their formation. Processes responsible for observed differences in fluids and deposits from distinct geologic settings include (a) fluid-rock interaction (with temperature, pressure and crustal composition as variables), (b) magmatic acid volatile input and, (c) local seawater entrainment and mixing with hydrothermal fluids, coupled with sulfide precipitation and metal remobilization. REE distributions in vent fluids in the Manus Basin exhibit a wide range of chondrite-normalized patterns that contrast with the relatively uniform distributions observed in mid-ocean ridge vent fluids. This heterogeneity is attributed to marked differences in fluid pH and fluoride and sulfate concentrations that significantly affect REE solubility. The data indicate that REEs can be used as indicators of the styles of magmatic acid volatile input in back-arc hydrothermal systems. Anhydrite in deposits record the same range of REE patterns, suggesting that REE distributions preserved in anhydrite can be used as indicators of past magmatic acid volatile input. Vent fluid heavy metal and metalloid concentrations also exhibit considerable differences. High metal concentrations in EMB versus MSC vent fluids reflect low pH, largely from input of magmatic acid volatiles (indicated by fluoride concentrations greater than seawater). In EMB, metal concentrations are locally affected by dissolution of previously deposited sulfide owing to low pH conditions affected by magmatic acid volatile input or seawater entrainment and mixing with hydrothermal fluid that leads to sulfide precipitation and secondary acidity generation.
(cont.) Massive sulfide deposits in the Manus Basin exhibit a wide range of mineral compositions and heavy metal enrichments. The formation of Zn-rich (sphalerite/wurtzite) deposits in the MSC and of Cu-Fe and Cu-As-rich (chalcopyrite, tennantite) deposits in the EMB reflects differences in the conditions of sulfide precipitation (temperature, pH) and in metal concentrations. The data suggest that heavy metal and metalloid distributions in massive sulfide deposits can be used as indicators of the conditions of vent deposit formation.
by Paul R. Craddock.
Ph.D.
5
Delaine, Maxence. "La composition des thèques d'amibes xénosomiques : utilisation potentielle comme bio-indicateur des dépôts de particules d’origine atmosphérique." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2017/document.
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Les amibes à thèque, également appelés thécamoebiens, sont des micro-organismes unicellulaires, qui construisent une enveloppe rigide, appelée thèque (Adl et al., 2012). Ces thèques ont des tailles, formes et natures très variées (Ogden & Hedley, 1980). Les récentes études sur la composition des thèques ont conduit à émettre l’hypothèse que les amibes xénosomiques (constituées de particules exogènes), peuvent constituer des bio-indicateurs pertinents de la diversité particulaire de l’environnement minéral, organique et biologique dans lequel elles évoluent.L’objectif principal des recherches menées au cours de cette thèse vise donc à caractériser la composition des thèques d’amibes xénosomiques et à en évaluer leur utilisation potentielle en tant que bio-indicateurs des dépôts de particules d'origine atmosphérique. Pour cela, des thèques d’amibes ont été analysées in situ en conditions naturelles et après dépôts artificiels de particules minérales allochtones.Ces travaux permettent de dégager plusieurs conclusions majeures :(1) La taille des particules minérales intégrées dans la thèque xénosomique de Bullinularia indica est similaire à celle des particules minérales transportées dans l'atmosphère; (2) les particules minérales intégrées dans les thèques sont des silicates stables dans les conditions physico-chimiques régnant dans les tourbières, les bryophytes et les sols étudiés; (3) certains minéraux comme la phlogopite, même lorsqu’ils sont présents en de fortes concentrations, ne sont jamais intégrés par les amibes; (4) la combinaison des observations portant sur la taille, la forme et la nature des particules utilisées par des amibes xénosomiques permet de poser les bases de l'utilisation des amibes à thèques pour la bio-indication de la diversité particulaire atmosphérique récente ou ancienneTheca-like amoebae, also called thecaamoebius, are unicellular microorganisms, which construct a rigid envelope called theca (Adl et al., 2012). These themes have very varied sizes, shapes and natures (Ogden & Hedley, 1980). Recent studies on the composition of the themes have led to the hypothesis that xenosomal amoebae (constituted by exogenous particles) can constitute relevant bio-indicators of the particulate diversity of the mineral, organic and biological environment in which they evolve . The main objective of the research carried out during this thesis is therefore to characterize the composition of the xenosomal amoebae and to evaluate their potential use as bioindicators of deposits of atmospheric particles. For this purpose, amoeba theae were analyzed in situ under natural conditions and after artificial deposits of allochtonous mineral particles. Several major conclusions can be drawn from this work: (1) The size of the mineral particles integrated in the xenosomal theca of Bullinularia indica Is similar to that of mineral particles transported into the atmosphere; (2) the mineral particles integrated into the thecs are stable silicates under the physico-chemical conditions prevailing in the peatlands, bryophytes and soils studied; (3) some minerals such as phlogopite, even when present in high concentrations, are never integrated by amoebae; (4) the combination of observations on the size, shape and nature of the particles used by xenosomic amoebae forms the basis for the use of tea amoeba for bioindication of recent or former atmospheric particulate diversity
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Danna, James G. "Experimental study of clast orientation in gravels deposited by unidirectional flow." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/57919.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1985.Microfiche copy available in Archives and Science.
Bibliography: leaves 83-84.
by James G. Danna.
M.S.
7
Dunlop, Luke Arthur. "Investigation and comparison of oxide thin films deposited via two low temperature atmospheric pressure routes." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609263.
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Durrieu, Gael. "Apports fluviaux et atmosphériques d'éléments traces métalliques et métalloïdes en zone côtière méditerranéenne : cas de la rade de Toulon." Electronic Thesis or Diss., Toulon, 2022. http://www.theses.fr/2022TOUL0015.
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Les zones côtières représentent un enjeu majeur en termes d’activités économiques et de préservation d’un bon état chimique et écologique du milieu naturel. Si à l’échelle globale (mer ou océan) les flux de contaminants notamment les éléments traces métalliques et métalloïdes (ETMM) sont relativement bien étudiés et décrits, ce n’est pas le cas des zones plus enclavées à une échelle plus locale. La rade de Toulon qui possède une morphologie semi-fermée est entourée d’une métropole importante (450 000 habitants) avec une forte activité anthropique (premier port militaire en France, ports civils, transport de passagers, aquaculture, …). Ces activités présentes et passées comme la deuxième guerre mondiale, ont conduit à une forte contamination sédimentaire ainsi qu’un fort gradient de concentrations en ETMM entre le Sud de la grande rade, connecté à la mer Méditerranée, et les parties les plus enclavées de la petite rade. Dans ce contexte de zone côtière contaminée, l’objectif de ce travail est d’évaluer la contribution des apports fluviaux et atmosphériques en ETMM à la rade de Toulon. Le mode d’échantillonnage proposé associant des capteurs de terrain, des pièges à particules et des prélèvements ponctuels différenciés entre l’étiage et la crue ont permis d’obtenir une chronique d’apports en ETMM prenant en compte la variabilité météorologique. Les résultats montrent que les apports en ETMM par les rivières (Las et Eygoutier) sont prépondérants durant les crues et dans la fraction particulaire et, sont plus particulièrement préoccupant pour le cuivre et le zinc qui dépassent les seuils réglementaires. Dans le Las, l’apport prépondérant reste cependant le cuivre dissous durant les crues. Dans l’Eygoutier, les valeurs obtenues sont inférieures aux mesures précédemment réalisées en 2004. Les apports en étiage sont largement minoritaires et des teneurs élevées en cadmium et mercure dans les particules ont été mesurées sans pouvoir identifier leur source. Les apports atmosphériques en ETMM sont dominés par la fraction particulaire avec des teneurs dépassant les seuils réglementaires d’un facteur 2 à 4 en cuivre, plomb et zinc. A l’échelle de la rade, les apports fluviaux restent supérieurs aux apports atmosphériques pour tous les ETMM. En faisant un bilan sur l’ensemble de la rade et en prenant en compte les autres sources existantes (ports, ruissellement, stations d’épuration, diffusion sédimentaire), la contribution des apports fluviaux et atmosphériques est estimée à 4 % pour le mercure, autour de 30 % pour le cuivre et le cadmium et près de 70 % pour le plomb et le chrome. Le bilan des flux d’ETMM dans la rade conduit à décrire la rade comme une source de contamination pour la mer Méditerranée. Ceci est confirmé par l’export net calculé pour le plomb, le mercure ou le cadmium tandis que pour le cuivre et le nickel des sources manquantes restent à être déterminées pour confirmer l’hypothèse. Pour le zinc et l’arsenic, la trop grande variabilité empêche de conclure car, ces estimations nécessitent d’être affinéesCoastal areas represent a major issue in terms of economic activities and preservation of a good chemical and ecological status of the natural environment. If on a global scale (sea or ocean) the flow of contaminants, especially trace metals and metalloids (TMM) are relatively well studied and described, this is not the case for more enclosed areas on a more local scale. The Toulon Bay, which has a semi-closed morphology, is surrounded by a large urban area (450 000 inhabitants) with a strong anthropic activity (first military port in France, civil ports, passenger transport, aquaculture, ...). These present and past activities, such as the Second World War, have led to a strong sedimentary contamination as well as a strong gradient of concentrations in TMM between the South of the large bay, connected to the Mediterranean Sea, and the most enclosed parts of the small bay. In this context of contaminated coastal zone, the objective of this work is to evaluate the contribution of the fluvial and atmospheric contributions in TMM to the Toulon Bay. The proposed sampling method associating field sensors, particle traps and punctual sampling differentiated between base flow and flood allowed to obtain a chronicle of TMM inputs considering the meteorological variability. The results show that the inputs of TMM by the rivers (Las and Eygoutier) are preponderant during floods and in the particulate fraction and are more particularly worrying for copper and zinc which exceed the regulatory thresholds. In the Las, the preponderant contribution remains however the dissolved copper during the flood. In the Eygoutier, the values obtained are lower than the measurements previously carried out in 2004. Base flow inputs are largely in the minority and high levels of cadmium and mercury in the particles were measured without being able to identify their source. Atmospheric inputs of TMM are dominated by the particulate fraction with levels exceeding the regulatory thresholds by a factor of 2 to 4 for copper, lead and zinc. At the bay scale, river inputs remain higher than atmospheric inputs for all the TMM. By making a balance on the whole of the bay and by considering the other existing sources (ports, runoff, wastewater treatment plant, sedimentary diffusion), the contribution of river and atmospheric inputs is estimated at 4% for mercury, around 30% for copper and cadmium and nearly 70% for lead and chromium. The balance of TMM inputs in the bay leads to describe the bay as a source of contamination for the Mediterranean Sea. This is confirmed by the net export calculated for lead, mercury, and cadmium, while for copper and nickel missing sources remain to be determined to confirm the hypothesis. For zinc and arsenic, too much variability prevents conclusions being drawn, and these estimates need to be refined
9
Fahrni, Jason K. "Assessment of the Severity, Sources, and Meteorological Transport of Ambient and Wet Deposited Mercury in the Ohio River Valley Airshed." Ohio University / OhioLINK, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1125427320.
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Elwin, Gareth Steven. "Atmospheric pressure chemical vapour deposition of the nitrides and oxynitrides of vanadium, titanium and chromium." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322369.
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Stephenson, Morgan. "Effects of deposited sediment and turbidity on survival and growth of Orbicella faveolata recruits." Thesis, NSUWorks, 2019. https://nsuworks.nova.edu/occ_stuetd/509.
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Corals are frequently exposed to elevated turbidity and deposited sediment caused from coastal construction, dredging, and/or beach renourishment. This study addresses the effects of turbidity and deposited sediment on the survival and growth of newly settled and 6-week-old Orbicella faveolata recruits and disentangles the effects of turbidity and deposited sediment. We conducted two experiments in which newly settled coral recruits were reared in one of ten different turbidity and deposited sediment treatments for five weeks (0 NTU/ 0 mg cm-2, 3.4 NTU/ 0 mg cm-2, 8.2 NTU/ 0 mg cm-2, 16 NTU/ 0 mg cm-2, 29.1 NTU/ 0 mg cm-2, 0 NTU/ 0 mg cm-2, 3.4 NTU/ 27.7 mg cm-2, 8.2 NTU/ 50 mg cm-2, 16 NTU/ 101 mg cm-2, 29.1 NTU/ 220 mg cm-2). The highest turbidity treatment in the absence of deposited sediment (29.1 NTU/ 0 mg cm-2) had the best survival, suggesting that turbidity in the absence of sediment is beneficial to coral recruits, as it decreases harmful light levels. However, when recruits were exposed to both turbidity and deposited sediment, representative of normal coastal construction conditions, high turbidity when coupled with deposited sediment (16 NTU/ 101 mg cm-2 and 29.1 NTU/ 220 mg cm-2) had negative effects on coral recruits. Based on the results from the first experiment, the experiment was repeated with six-week-old symbiotic recruits for two weeks to determine if the sensitivity to light and benefits of high turbidity were related to the presence of symbionts. Six-week-old recruits also had the highest survival in the highest turbidity treatment, suggesting that light sensitivity by coral recruits is not dependent on the presence of symbionts within the first six weeks post-settlement. While the low light associated with turbidity increases recruit survival, turbidity is a proxy for deposited sediment, which has negative effects on coral recruits. Based on the results from this study, regulations should prevent turbidity from exceeding 8.2 NTU to prevent excessive deposited sediment on coral reefs, and its deleterious effects on corals.
12
Evans, Guy Nathaniel. "Trace element proxies and mineral indicators of hydrothermal fluid composition and seafloor massive sulfide deposit formation processes." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111731.
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Thesis: Ph. D. in Marine Geology, Joint Program in Marine Geology and Geophysics (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2017.Cataloged from PDF version of thesis.
Includes bibliographical references.
This thesis analyzes compositions of seafloor massive sulfide (SMS) deposits and related hydrothermal vent fluids to identify proxies of reaction zone conditions (host-rock lithology, hydrothermal fluid temperature and chemistry). Chapter 2 investigates the morphology, mineralogy, and geochemistry of SMS deposits from six vent fields along the Eastern Lau Spreading Center (ELSC), demonstrating that ELSC SMS deposits record differences in hydrothermal fluid temperature, pH, sulfur fugacity and host-rock lithology related to proximity to the nearby Tonga Subduction Zone. Chapters 3 and 4 focus on partitioning of Co, Ni, Ga, Ag, and In between hydrothermal vent fluids and chalcopyrite lining fluid conduits in black smoker chimneys. Chapter 3 develops secondary ion mass spectrometry (SIMS) as a technique to measure Co, Ni, Ga, Ag, and In in chalcopyrite and identifies a correlation between Ga and In in chalcopyrite and hydrothermal fluid pH. Chapter 4 presents new data on these elements in ELSC hydrothermal fluids that, combined with SIMS analyses of chalcopyrite chimney linings and previously published data on vent fluids from the Manus Basin, provide evidence that supports partitioning of Ag a lattice substitution for Cu. Together, concentrations of Ga, In, and Ag in chalcopyrite provide proxies of hydrothermal fluid pH and metal (i.e., Ag and Cu) contents.
by Guy Nathaniel Evans.
Ph. D. in Marine Geology
13
Oettinger, Wolf P. "Untersuchung von Atmospherics (atmosphärischer Impulsstrahlung) im Hinblick auf prägende Signaleigenschaften /." Taunusstein : Driesen, H.H. Dr, 2008. http://deposit.d-nb.de/cgi-bin/dokserv?id=3112092&prov=M&dok_var=1&dok_ext=htm.
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Alloteau, Fanny. "Contribution à la compréhension des mécanismes de l'altération atmosphérique des verres et étude d'un traitement de protection à base de sels de zinc." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEC004/document.
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Parmi la grande diversité des productions de verres anciens appartenant aux collections muséales (vaisselle, vitres, vitraux, bijoux, perles, incrustations, statuettes, mosaïques, émaux, céramiques glaçurées…), une proportion importante montre à leur surface les signes sévères d’une altération atmosphérique (présence de sels alcalins, fracturation) conduisant à une perte de transparence voire une perte irréversible de matière. Ces œuvres sont produites essentiellement à partir du Moyen-Âge (XIIe-XIIIe siècle), avec une forte représentation aux XVIe, XVIIe et XVIIIe siècles. Les verriers ont en effet appliqué alors de nouvelles recettes par rapport à celles des périodes anciennes conduisant à une instabilité chimique du verre vis-à-vis de l’humidité ambiante. Quant aux œuvres actuellement en bon état de conservation, elles sont également susceptibles de se dégrader au cours du temps, selon leur composition et leur condition de conservation. À ce jour, le meilleur moyen de protection mis en œuvre par les conservateurs et les restaurateurs pour ralentir sensiblement cette altération est le contrôle de la température et de l’humidité de l’environnement de conservation (vitrines d’exposition spécifiques, réserves de musée). Cependant, afin de préserver cet important patrimoine culturel, il est d’un intérêt majeur de proposer de nouvelles solutions de protection qui soient à la fois plus efficaces et moins coûteuses pour les musées. C’est dans ce contexte que s’inscrit le présent projet de thèse. Il vise d’une part à faire progresser la compréhension des mécanismes d’altération atmosphérique des verres d’oxyde, d’autre part à mettre au point un traitement de protection à base de sels de zinc adapté au contexte muséal. En s’inspirant de procédés industriels qui exploitent de manière empirique l’effet protecteur des ions zinc (stockage et transport du verre plat, produits de lavage du verre en lave-vaisselle), nous avons en effet d’ores-et-déjà mis en évidence le fort potentiel de très faibles quantités de sels de zinc pour réduire efficacement les cinétiques d’altérations de compositions verrières altérables du patrimoineIn the cultural heritage field, it is of major concern to develop new protective methods for ancient glass objects that decay under atmosphere. In this framework, two complementary research directions are undertaken. The first one aims to get a better understanding of the glass atmospheric alteration mechanisms at a small scale. The second one is focused on the potentiality of a zinc salt surface treatment. By the mean of accelerated ageing experiments (temperature and humidity control) of replica glasses (alkali silicates), untreated or zinc salts treated, the evolution of the glass surface and sub-surface with atmospheric alteration are evaluated at different scales (macro – nano). These surface modifications are compared to the properties of hydrated layers of ancient glass objects that have been altered over decades. The influence of the ageing temperature and the glass composition on the atmospheric alteration mechanisms are highlighted. In particular, these parameters affect the proportion of alkali elements that are retained into the hydrated layer, which would severely impact the glass chemical durability. Positive effect of a zinc salt treatment to reduce the replica glasses hydration kinetics is shown with ageing experiments at 80 °C or 40 °C, when the glass surfaces are not pre-altered before the deposit. The formation of thermally activated zinc species that react with the glass surface are put in evidence as well as their predominant role in the protection mechanisms. Therefore, a zinc salt treatment might be considered if a heating step of the glass object is accepted (around 60 °C). However, the treatment performances seem to be strongly dependent on the surface alteration degree before the deposit. This point is critical for the relevance of the treatment for the glass artwork conservation and should be investigated deeper. Others directions of research are arisen in this work and should be followed to propose new protective methods in the longer terms
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Alloteau, Fanny. "Contribution à la compréhension des mécanismes de l'altération atmosphérique des verres et étude d'un traitement de protection à base de sels de zinc." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEC004.
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Parmi la grande diversité des productions de verres anciens appartenant aux collections muséales (vaisselle, vitres, vitraux, bijoux, perles, incrustations, statuettes, mosaïques, émaux, céramiques glaçurées…), une proportion importante montre à leur surface les signes sévères d’une altération atmosphérique (présence de sels alcalins, fracturation) conduisant à une perte de transparence voire une perte irréversible de matière. Ces œuvres sont produites essentiellement à partir du Moyen-Âge (XIIe-XIIIe siècle), avec une forte représentation aux XVIe, XVIIe et XVIIIe siècles. Les verriers ont en effet appliqué alors de nouvelles recettes par rapport à celles des périodes anciennes conduisant à une instabilité chimique du verre vis-à-vis de l’humidité ambiante. Quant aux œuvres actuellement en bon état de conservation, elles sont également susceptibles de se dégrader au cours du temps, selon leur composition et leur condition de conservation. À ce jour, le meilleur moyen de protection mis en œuvre par les conservateurs et les restaurateurs pour ralentir sensiblement cette altération est le contrôle de la température et de l’humidité de l’environnement de conservation (vitrines d’exposition spécifiques, réserves de musée). Cependant, afin de préserver cet important patrimoine culturel, il est d’un intérêt majeur de proposer de nouvelles solutions de protection qui soient à la fois plus efficaces et moins coûteuses pour les musées. C’est dans ce contexte que s’inscrit le présent projet de thèse. Il vise d’une part à faire progresser la compréhension des mécanismes d’altération atmosphérique des verres d’oxyde, d’autre part à mettre au point un traitement de protection à base de sels de zinc adapté au contexte muséal. En s’inspirant de procédés industriels qui exploitent de manière empirique l’effet protecteur des ions zinc (stockage et transport du verre plat, produits de lavage du verre en lave-vaisselle), nous avons en effet d’ores-et-déjà mis en évidence le fort potentiel de très faibles quantités de sels de zinc pour réduire efficacement les cinétiques d’altérations de compositions verrières altérables du patrimoineIn the cultural heritage field, it is of major concern to develop new protective methods for ancient glass objects that decay under atmosphere. In this framework, two complementary research directions are undertaken. The first one aims to get a better understanding of the glass atmospheric alteration mechanisms at a small scale. The second one is focused on the potentiality of a zinc salt surface treatment. By the mean of accelerated ageing experiments (temperature and humidity control) of replica glasses (alkali silicates), untreated or zinc salts treated, the evolution of the glass surface and sub-surface with atmospheric alteration are evaluated at different scales (macro – nano). These surface modifications are compared to the properties of hydrated layers of ancient glass objects that have been altered over decades. The influence of the ageing temperature and the glass composition on the atmospheric alteration mechanisms are highlighted. In particular, these parameters affect the proportion of alkali elements that are retained into the hydrated layer, which would severely impact the glass chemical durability. Positive effect of a zinc salt treatment to reduce the replica glasses hydration kinetics is shown with ageing experiments at 80 °C or 40 °C, when the glass surfaces are not pre-altered before the deposit. The formation of thermally activated zinc species that react with the glass surface are put in evidence as well as their predominant role in the protection mechanisms. Therefore, a zinc salt treatment might be considered if a heating step of the glass object is accepted (around 60 °C). However, the treatment performances seem to be strongly dependent on the surface alteration degree before the deposit. This point is critical for the relevance of the treatment for the glass artwork conservation and should be investigated deeper. Others directions of research are arisen in this work and should be followed to propose new protective methods in the longer terms
16
Messing, Paul. "Pesticides in the air, atmospheric deposits, and surface waters of Canada." 2015. http://hdl.handle.net/1993/30175.
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In Canada, more than 35 million kilograms of pesticide active ingredients are applied annually on agricultural land with about 84% of this mass applied in the Canadian Prairies Provinces. Pesticide residues may become airborne through post-volatilization losses from land, water or vegetative surfaces, via wind-eroded soil, and by spray drift during pesticide application. Once in the air, pesticides may be dispersed and transported as parent molecules or as degradation products. Currently used and legacy pesticide air concentrations were measured in the agricultural region of the Prairie Provinces and the northern subarctic and arctic regions of Canada in 2005 and 2007. More intensive air sampling was conducted across the province of Manitoba in 2008 and 2009. Separate wet versus dry atmospheric deposition samples and wetland water samples were also taken in these years. In general, pesticides were detected in the monitored environmental media as mixtures with the frequency and concentrations detected being largest for pesticides that were applied on-site. Although the most commonly used herbicides in western Canadian agriculture were frequently present in the air in the regions where they are applied, they appeared infrequently and at low levels in the Canadian Subarctic, Arctic, and remote sites far from agricultural pesticide applications. Results also indicated that the concentrations of legacy pesticides such as lindane (γ-HCH) and its manufacturing by-product prior to 1971 (α-HCH) continued to decrease over time in the Canadian environment. Air concentrations of pesticides in agricultural regions, and subsequent wet and dry atmospheric deposition, contaminated surface water following periods of pesticide application. Dry deposition contributed 12–51% of the total deposition. Calculations were performed to predict wetland water column pesticide concentrations based on total atmospheric deposits alone. The estimated concentrations were closest to actual concentrations for MCPA and predictions were also reasonable for a range of other herbicides, but a source other than atmospheric deposition was clearly relevant to the detection of clopyralid in the wetland water-column. Individual herbicide concentrations did not exceed Canadian water quality guidelines for the protection of aquatic life.
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Letsoalo, Mokgehle Refiloe. "Speciation of arsenic water and sediments from Mokolo and Greate Letaba Rivers, Limpopo Province." Thesis, 2017. http://hdl.handle.net/10386/1927.
Full textAbstract:
Thesis (M. Sc.(Chemistry)) -- University of Limpopo, 2017.Great Letaba and Mokolo Rivers are major sources of water for domestic use, agriculture and recreational activities in Limpopo Province, South Africa. These Rivers are predisposed to pollution sources from atmospheric deposition of mine dust, emissions from power stations and burning fuel, return flows from agriculture and municipal wastewater discharges and sewage effluents, which may potentially affect the quality of water and the inhabiting biota. Arsenic (As) is an element of prime concern in aquatic systems exposed to such pollution sources due to its toxicity to humans and aquatic life. The quantification and speciation of As in Mokolo and Great Letaba Rivers is important to assess the current levels and predict future trends in the quality of the two rivers. Speciation of As in water and sediments is crucial since the toxicity depends on its chemical forms. In this study, various analytical approaches were explored to precisely identify and quantify different As species in water and sediment samples collected from Great Letaba and Mokolo Rivers. Sample preparation was carried out with an intensive care to efficiently identify and quantify As species. Identification of each species in the samples was based on matching standard peaks with retention times by simple injection of standards of As species into Hamilton PRP X100 column. The chromatographic separation and determination of As3+, dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and As5+ in water and sediment samples were achieved by on-line coupling of high performance liquid chromatography (HPLC) to inductively coupled plasma-mass spectrometry (ICP-MS). A novel extraction method for As species in sediments based on 0.3 M (NH4)2HPO4 and 50 mM EDTA showed no species interconversion during extraction. Baseline separation of four As species was achieved in 12 minutes using gradient elution with 10 mM and 60 mM of NH4NO3 at pH 8.7 as mobile phases. The analytical figures of merits and validation of analytical procedures were assessed and adequate performance and percentage recoveries ranging from 81.1 – 102% for water sample and 73.0 – 92.0% for sediments were achieved. The As species concentration in water and sediment samples were found in the range 0.224 – 7.70 μg/L and 74.0 – 92.0 ng/g, respectively. The DMA was not detected in both water and sediment samples. viii The As content in sediments depends on the solid phase partitioning between inorganic As species and trace elements such as iron (Fe), manganese (Mn) and aluminium (Al). Knowledge of the extent of this partitioning is important to evaluate the distribution and pathways of As in water, aquatic organisms and possible exposure of animals and human beings. Therefore, total concentrations of As, Fe, Mn and Al in water and sediment samples were determined using ICP-MS and inductively coupled plasma–optical emission spectrometry (ICP-OES). The analytical procedures were validated using standard reference materials (SRMs) with percentage recoveries of trace elements ranging 84.0 – 95.6% for water samples and 75.0 – 120% for sediments. The As, Fe, Mn and Al concentrations obtained were further assessed for safe drinking water, irrigation water and for sediments quality about standard guidelines. Moreover, As species concentrations correlated with Fe, Mn and Al and the observed interactions depend on the adsorption capacities between As species and these trace elements. The inorganic species in water samples were also determined by employing off-line mode of solid phase extraction (SPE) procedure using multi-walled carbon nanotubes (MWCNTs) impregnated branched polyethyleneimine (BPEI) as an adsorbent material. The MWCNTs-BPEI characterised with X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Thermogravimetric analysis (TGA) techniques indicated successful modification of the nanomaterial. The MWCNTs-BPEI exhibited selective retention of As5+ in the presence of As3+ in water samples with the achieved pre-concentration factor of 23.3. The retained As5+ was then eluted and detected using ICP-MS. A limit of detection (LOD) of 0.0537 μg/L and limit of quantification (LOQ) of 0.179 μg/L were achieved. The obtained percentage recovery of 81.0% validated the SPE procedure for selective retention of As5+. The As5+ concentrations determined after the SPE procedure were found in the range of 0.204 – 7.52 μg/L, which are in good agreement with As5+ results obtained using HPLC-ICP-MS.
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Vasavada, Ashwin R. "I. Temperatures of polar ice deposits on mercury and the moon. II. Jovian atmospheric dynamics from Galileo imaging." Thesis, 1998. https://thesis.library.caltech.edu/7447/1/Vasavada_ar_1998.pdf.
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Locations on Mercury that produce ice-like radar responses lie within impact craters that have very cold, permanently shaded floors. The retention of possible ice deposits is determined largely by their temperature. We present model- calculated temperatures of flat surfaces and surfaces within bowl-shaped and flatfloored polar impact craters. Our model includes appropriate insolation cycles, realistic crater shapes, multiple scattering of sunlight and infrared radiation, and depth and temperature-dependent regolith thermophysical properties. Unshaded water ice deposits are rapidly lost to sublimation on Mercury and the Moon. Meter-thick deposits of water ice are stable to evaporation over the age of the solar system if located in the permanently shaded portions of flat-floored craters within 10° latitude of the poles of either planet. Results for craters associated with radar features on Mercury are consistent with stable water ice deposits if a thin regolith layer thermally insulates the lowest latitude deposits, reducing sublimation rates. A regolith cover also is a diffusion barrier, reduces losses from sputtering, impact vaporization, and exposure to H Lyα, and is implied independently by the radar observations. Impact craters near the lunar poles contain colder permanently shaded regions than those on Mercury.
During the first six orbits of the Galilee spacecraft's prime mission, the Solid State Imaging system acquired multispectral image mosaics of Jupiter's Great Red Spot, an equatorial belt/zone boundary, a "5-µm hotspot" similar to the Galilee Probe entry site, and two of the classic White Ovals. We present mosaics of each region approximating their appearance at visible wavelengths and showing cloud height and opacity variations. The local wind field is derived by tracking cloud motions between multiple observations of each region with time separations of roughly one and ten hours. Vertical cloud structure is derived in a companion paper by Banfield et al.(1998). Galilee's brief, high-resolution observations complement Earth-based and Voyager studies, and offer local meteorological context for the Galileo Probe results. Images taken one hour apart reveal small, rapidly changing, high cloud features possibly analogous to terrestrial thunderstorms. Our results show that the dynamics of the zonal jets and large vortices have changed little since Voyager, with a few exceptions. We detect a cyclonic current within the center of the predominantly anticyclonic Great Red Spot. The zonal velocity difference between 0°s and 6°S has increased by 20 m s^(-1). We measure a strong northeast flow approaching the hotspot. This flow indicates either massive horizontal convergence or the presence of a large anticyclonic vortex southeast of the hotspot. The current compact arrangement of two White Ovals and a cyclonic structure greatly perturbs the zonal jets in that region.
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Wang, Hung-Shen, and 王洪笙. "CO sensing by reactive-sputter-deposited PdO nanoflakes at atmospheric pressure." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/44534695408298281241.
Full textAbstract:
碩士國立交通大學
工學院半導體材料與製程設備學程
102
This study deposited PdO nanoflake thin films on the SiO2/Si substrates by reactive sputter deposition, and investigated CO sensing properties of the PdO thin film. The thin film has a flake-like nanostructure with a large surface area and, therefore, the film can provide a large amount of adsorption sites for CO molecules. Moreover, because of the ultrathin thickness of the nanoflake, the space charge region induced by O2 or CO adsorption will occupy most volume of the nanoflake, resulting in a very sensitive change in the electrical resistance of the film. According to this study, the PdO thin film exhibits different electrical response behavior toward CO adsorption at different temperature ranges. At low temperatures (≤100oC), CO molecules react with (or replace) anionic oxygen molecules (O2-) and thus change electrical properties of the thin film. Because PdO is a p-type semiconductor, the depletion region in the nanoflake, which is formerly formed due to oxygen ionosorption, is widened upon CO adsorption, leading to the increase in the electrical resistivity of the PdO thin film. At 150oC, the CO molecules can react with surface oxygen atoms, thereby reducing PdO. However, in this temperature range, subsurface oxide can be formed on the reduced Pd surface, and the alternative oxidation-reduction reaction causes oscillatory electrical response during the CO sensing process. At higher sensing temperatures ≥200oC, the change in the sensing current of the PdO thin film upon CO exposure reaches a steady level, suggesting that reactions between adsorbed CO, pre-adsorbed oxygen ion and lattice oxygen are in dynamic equilibrium.
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Wu, Shin-Yi, and 吳信誼. "Investigation of Low Temperature Atmospheric Pressure Plasma Deposited SiOx Thin Films." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/96367815155339112756.
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碩士元智大學
化學工程與材料科學學系
97
In this study, atmospheric pressure plasma chemical vapor deposition (APPCVD) technique was employed to deposit SiOx thin film on Polycarbonate (PC) substrates. We anticipate improving the surface properties of plastic substrates. Hexamethyldisilazane (HMDSN) and Hexamethyldisiloxane (HMDSO) were utilized as the precursor for APPCVD. Atmospheric pressure plasma deposited SiOx thin films have been analyzed by the optical thin-film thickness detector, FTIR, XPS, AFM, and UV-VIS. With various operational parameters including in RF plasma power level, the distance of nozzle to substrate, oxygen gas flow rate, APP deposited SiOx thin films have been investigated for the change of surface properties and chemical composition. Moreover, Optical Emission Spectrometry (OES) was used for analysis the luminous gas phase of APPCVD process. The experimental results determined that the oxygen gas flow rate is the key point of APPCVD process. Depending on the proper operational parameters, SiOx thin film has excellent inorganic features. The hardness of atmospheric pressure plasma deposited PC substrates was improved from 6B to H, and obtains a transmission of 93 % in the visible region. Atmospheric pressure plasma surface modification technique was employed to improve adhesion between SiOx thin film and PC substrate. After atmospheric pressure plasma surface modification, the adhesion of plasma modified PC substrate is improved from 0B (percent area removed＞65 %) to 5B (none area removed).
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Hsu, Chun-Ming, and 許峻銘. "Characterization of Oxide Thin Films Deposited by an Atmospheric Pressure Plasma Jet." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/35837955388715490041.
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碩士國立臺灣大學
化學工程學研究所
102
Deposition zinc oxide and silica-like thin films by the atmospheric pressure plasma jet were studied. To understand the plasma system property and application fields, we first investigate into the plasma optical emission spectra and gas temperature by changing the manipulate variable such as applied voltage, gas type and flowrate. Our research has demonstrated that higher applied voltage and lower gas flowrate will decrease the plasma gas temperature because of the different energy density. But the higher flowrate cause the plasma gas have more excited molecules. By the simulation of the plasma downstream intensity distribution, temperature trend and NO concentration, we found that the turbulence type matchs the downstream flowfield well and it illustrates the non-negligible of outside ambient gas. Futher, our study shows the plasma gas temperature and substrate temperature by the method of simulation molecules emission and thermalcouple measurement. The downstream gas temperature are between 950 K to 1200 K, which makes the plasma system belonging to high temperature plasma type. To deposit zinc oxide thin films, we use the 1.7 MHz nebulizer and nitrogen carrier gas to spray the precursor solution into the plasma system. The different precursor effect, applied voltage and gas flowrate effect were studied in this research. First, we found the only one precursor, zinc chloride, can deposit the less roughness, smooth and high crystalline thin films. Otherwise the particle-like structure appears. Next, to find the optimized condition of zinc chloride as precursor deposits zinc oxide thin films, the gas flowrate and applied voltage were setting as manipulate variable. In our study, we found that under the applied voltage 275 V and gas flow rate 30 slm, the deposition has best film property with resistivity of 1.4 ohm-cm and transimmion near 90 %. Otherwise the deposition will appear the sheet-like structure and has poor optical and electric property. By the XRD identified, we found the sheet-like structure is the ZHC (Zn5(OH)8Cl2‧H2O), which is the intermedia of the reaction. The appearance of ZHC can be explained by the non-enough power and shorter residence times in those condition. In next research topic, the silica-like thin films deposited by the APPJ were studied. In this system, we use the bubbler method with nitrogen as the carrier gas to send the saturated vapor pressure to the plasma system. Three different precursors were tested, which are tetraethylorthosilicate (TEOS), Hexamethyldisiloxane (HMDSO) and hexamethyldisilazane (HMDSN). Each precursor has their optimized deposited condition and all deposition show the inorganic-like silica structure. In the TEOS system, we found the deposition rate was much lower than the others but the film has the advantage of smoothness and well-coverage. In the HMDSN system, the deposition rate were rapid but the films have worst leakage current density. It is in regard to its complicated bonding and structure. On the contrary, the HMDSO system has advantage of higher deposition rate, less-roughness and lower leakage current. In this research, we use films deposited from HMDSO as the dielectric layer in the thin films transistor (TFT) and it can work quite well. This TFT result shows the potential and capable of this atmospheric pressure deposited films as the device’s dielectric layer.
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Liao, Ming-Wei, and 廖銘瑋. "Flame Retardant of Silicon Dioxide Film Deposited by Atmospheric Pressure Plasma Chemical Vapor Deposition." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/29747518928284000832.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
96
Atmospheric pressure (AP) plasma chemical vapor deposition (CVD) process is utilized in this paper. We coated silica films on polycarbonate (PC) to enhance the flame retardant of PC. The AP apparatus is developed by ITRI. The plasma reactor operates by feeding helium gas between two electrodes driven by a Radio frequency (RF) power at 13.56 MHz at atmospheric pressure and near room temperature. The organic silicon source tetraethoxysilane (TEOS) was utilized as the precursor of silica films. With distinct experiment factors, such as the flow rate of precursor, power and flow rate of oxygen, we measure the thickness to calculate deposition rate, surface roughness, and porosity of the film. Moreover, the variation of the film’s properties were analyzed by Fourier-transform infrared spectrometer (FTIR), atomic force microscope (AFM) and scanning electron microscopy (SEM). The promotion of PC’s flame retardant is illustrated by limiting oxygen index. The result presented the porosity of the silica film deposited by AP-PECVD increased with higher deposition rate. We should choose the lower deposition rate experiment parameter to get the denser film. The denser film coated on PC raised the LOI value from 22 to 27. However, the porous film can’t contribute any promotion to LOI value.
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Kuo, Chih-Cheng, and 郭志成. "Mechanical Properties of Silicon Dioxide Film Deposited by Atmospheric Pressure Plasma Chemical Vapor Deposition." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/85781919887774858894.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
95
Atmospheric pressure plasma jet (APPJ) chemical vapor deposition (CVD) technique is utilized in this paper. The jet operates by feeding nitrogen gas between two electrodes that driven by a 20 kHz frequency and 500 W power source at atmospheric pressure and near room temperature. The organic silicon source Hexamethyldisazane (HMDSN) was utilized as the precursor of silica films. With distinct experiment factors, such as the flow rate of precursor, deposition time and substrate temperature, we measure the mechanical properties via nano-indentation system. Moreover, the variation of the mechanical properties analyzed by Fourier-transform infrared spectrometer (FTIR), atomic force microscope (AFM) and scanning electron microscopy (SEM) were obtained that correlated with surface porosity. The results presented that the Young’s modulus of silica films deposited by APPJ CVD increased with increases in the substrate temperature, however, decreased with increases in the active precursor concentration and deposition time. When the films were deposited near room temperature after annealing in air, these films exhibited denser structure and higher Young’s modulus. Comparing non-annealing with annealing at 800 ℃ in 5 hours, the Young’s modulus increased from 40.2 GPa to 54.7 GPa and average maximum depth (Rvm) modified more about 12 %.
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Chih-weiHuang and 黃致崴. "The study of SiOx thin-film deposited on optical plastic substrate by atmospheric plasma." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/30289655866436262001.
Full textAbstract:
碩士國立成功大學
化學工程學系碩博士班
101
This study established a set of continuous atmospheric pressure plasma system, treating surface for optical plastic substrate .The atmospheric plasma surface treatment is an economic and efficient method for low temperature surface treatment. Compared with the low-pressure plasma treatment, the atmospheric plasma chemical vapor deposition owns many advantages including atmospheric operation, in-line operation, no vacuum equipment needed, good compatibility with other processes, low equipment ,operation and maintenance cost, and high throughputs. In this experiment, HMDSO is a SiOx thin-film precursor which is deposed on optical plastic PC, PMMA substrate by PECVD. The study focus on two aspects, one is to study factors which affect the film and substrate adhesion; the second is to explore the impact of operation process on the chemical composition of the film. In this study, by controlling the coating parameters (Carrier gas flow, Scan speed, distance coated, coating time) and using different fabrication processes which modulating the thickness of SiOx films, various types of film with different surface properties and chemical composition are obtained. The surface can be highly hydrophilic (water contact angle of less than 5 degrees) or ultra-high anti-adhesion properties (water contact angle greater than 100 degrees). This experiment has been successfully deposited SiOx films of good adhesion on the PC substrate, and after modifying by hydrophobic process, it can withstand abrasion test up to 3000 times.
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Li, Zong-Han, and 李宗翰. "The Study of Surface Passivation Layers on Crystalline Silicon Deposited by an Atmospheric Plasma Source." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/98859170143264739783.
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Chou, Tung-Sheng, and 周東陞. "Characteristics and Uniformity Improvement of Ga-doped ZnO Thin Films Deposited by Atmospheric Pressure Plasma Jet." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/18717930059054498298.
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碩士國立臺灣大學
機械工程學研究所
102
Indium tin oxide (ITO) is one of the most widely used transparent conductive oxide (TCO) materials owing to its low resistivity (about 10-4 Ω&;#8729;cm) and excellent transmittance at visible light range (over 80%). However, its principal component, indium, is scarce and expensive. Many researchers are searching for substitutive materials for ITO aggressively. Polycrystalline ZnO films on glass have been extensively developed. By doping different metal atoms, Ga doped ZnO (GZO) deposited by sputtering can now compete with ITO both in cost and quality. Althrough sputtering has many advantedges, it must work in vacuum and, hence, raises the cost. In addition, it is not suitable for mass production when integrating with other processes is required. In this study we use atmospheric pressure plasma jet (APPJ) to deposit GZO thin films in atmospheric pressure environment without a vacuum chamber. Deposition of thin films on large area substrate is achieved by moving the nozzle with respect to the substrate, and the material is continuously sprayed during the scanning process. In this thesis we use APPJ generated by a DC pulse source to deposit GZO thin films on the glass substrate with a raster scanning trajectory. We discuss the effects of several key process parameters on the film deposited on smaller substrate with a dimension of 50 mm × 50 mm × 0.5 mm, and study the effects of electrical properties and uniformity of GZO thin films influenced by different trajectories and external flows on larger substrate, 185 mm × 117 mm × 0.5 mm in dimension. For the smaller sample, we adjust the parameters, including scanning recipe, Ga concentration, substrate temperature, gap, main gas flow rate and mixed carrier gas ratio, to understand the correlations between those parameters and photoelectric properties of the films, and as a result, obtain optimized recipes. In small samples, the films with about 150 nm thickness have better optoelectronic properties. By adjusting scanning repcipe on large area samples, we find that the sheet resistance is proportional to the air annealing time for samples experiencing single scan (refered as single-pass sample); Two-pass samples, in which the scan begins from one edge to the opposite edge and returns to the original edge so that the entire film enssentially consist of two layers, exhibit better uniformity in general, but show highest sheet resistance near the center of the substrate. In the external flow experiments, the pumping flow, caused by a fan designed to remove undeposited materials, alters the sheet resistance distribution, in particular the region with the highest sheet resistance. We apply α-step, equivalent circuit models, XRD, SEM, residual stress measurement and Hall measurement to analyze the reason of nonuniform electrical properties.
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Lin, Min-Han, and 林旻翰. "The Study of in-situ Hydrogen deposited a-IGZO active layer TFTs by Atmospheric Pressure-PECVD." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/55485841485252608498.
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碩士國立交通大學
電子工程學系 電子研究所
104
Recently, compared with the conventional a-Si TFTs, amorphous In-Ga-Zn-O (IGZO) thin film transistors have attracted attention that due to its better field-effect mobility (>10 cm2/V．S), larger Ion/Ioff ratio (>106), smaller subthreshold swing (SS) and better stability against electrical stress. Besides, compare with low temperature ploy-Si (LTPS) TFTs, the a-IGZO TFT do not need high temperature process to recrystallize and activate the dopant. Furthermore, the a-IGZO TFTs have low process temperature, high transmittance that can be applied to fabricate the full transparent TFT on flexible substrate. In this investigation, we used atmospheric-pressure PECVD (AP-PECVD) to deposit our IGZO active layer. With AP-PECVD, we could deposit IGZO thin film without vacuum system, thus, it could lower our cost, improved the throughput, and applied to large area manufacturing. We improved the a-IGZO TFT with AP-PECVD by adding the hydrogen while the deposition successfully. The electrical characteristics of a- IGZO TFT with active layer deposited with N2 as follow: the mobility was 3.36 cm2/V•S, the VT was 2.36 V, the subthreshold swing was 131 mV/decade, and the Ion/Ioff was 2.67×106. The TFT of a-IGZO active layer deposited with Ar+H2 gas exhibits higher mobility of 18.9 cm2/V•S, VT of 1.9 V, lower subthreshold swing of 112 mV/decade, higher Ion/Ioff of 2.54×107.
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王裕賢. "The Hot Corrosion Behavior of Cr-Mo Steels and 430 Stainless Steel with NaCl Deposits in Humidity Atmospheres." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/24533673405697497929.
Full textAbstract:
碩士國立臺灣科技大學
機械工程技術研究所
86
The purpose of this study is to investigate the effects of humidity and the hot-dipped aluminum-silicon treatment on the high temperature corrosion behavior of Cr-Mo alloy steels (STPA24 and STPA26) and 430 stainless steel. The experiments were performed at 450 to 750℃ in dry air, 10% and 50% humidity on specimens with 2mg/cm2 NaCl deposits. In atmospheres containing humidity, the dissociation mechanism of corrosion suppresses the formation of protective Cr2O3 but forms a bilayer porous scale. The corrosion rates increased by the solid diffusion of cations and the inward diffusion of hydrogen through the columnar oxide that grew form the alloy substrate to the outer scale. The hot-dipped aluminum-silicon treatment on STPA24 improved the hot-corrosion resistance of alloy markedly. The thickness of the alloying layer of the Al-Si hot-dipped specimen increased with increasing temperature, however, if was found that the alloying thickness does not decrease the corrosion resistance of the Al-Si hot-dipped alloy in the present study.
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Lin, Hsin-Tien, and 林心恬. "Material Properties Uniformity of Large Area Ga-doped ZnO Thin Films Deposited by Atmospheric Pressure Plasma Jet." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/23223303531162406867.
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碩士國立臺灣大學
機械工程學研究所
103
Transparent conductive oxides (TCO) thin films have drawn great interests and have been widely studied in recent years because of their important role as electrodes in various optoelectronic devices. One of the most widely used TCOs is tin-doped indium oxide (ITO) due to its high electrical conductivity, wide band gap, and high transparency in the visible spectral range. However, indium is rare in the Earth’s crust, which increases the production cost of ITO. Owing to its high chemical and mechanical stability, high abundance, nontoxicity, and exceptionally high electron mobility, zinc oxide (ZnO) thin film has become one of the popular alternatives to ITO films. ZnO is a well-known II-VI transparent semiconductor with a wide direct band gap of ~3.37 eV at room temperature, and a high exciton binding energy of 60 meV. ZnO heavily doped with metals, such as Al, Ga and In, shows Fermi level degeneration and thus behaves metallic along with its high transparency. Atmospheric pressure plasma jet (APPJ) technology provides a relatively simple and cost-effective method to deposit gallium-doped zinc oxide (GZO or ZnO:Ga) films onto large-area glass substrates in atmosphere. APPJ is simple and compatible with a wide range of precursor materials, facilitating the incorporation of suitable dopants without the need of heating the substrate over 200 C. We prepare GZO thin films on 185 mm × 117 mm glass substrates by APPJ, and study the effects of deposition parameter and trajectory on film sheet resistance uniformity. In this study, we find that during the deposition, the plasma jet deposition becomes more stable over time, and is able to deposit films with lower sheet resistance. By adjusting the substrate temperature and scanning speed, we find that films deposited with a higher substrate temperature and a lower scanning speed exhibit lower sheet resistance. The lowest sheet resistance of 49.4 Ω/□ and uniformity of 7% is obtained. In the external flow experiment, we observe that the flow field between the plasma jet chamber and the tool enclosure has a significant effect on the film quality and uniformity. The films near the exhaust of the enclosure tend to exhibit higher resistivity. The exact mechanism is still unclear and is a topic for future work. Using the concentric trajectory we can obtain films with the lowest sheet resistance in the central area. By using a raster scan on top of a concentric scan, we obtain a two-layer film with better uniformity.
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Chen, Kuan-Lin, and 陳冠霖. "Material Characterizations and Corrosion Behavior of Silicon Oxide Films Deposited by Atmospheric Pressure Plasma Jet：Flow Rate Effect." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/00851440921925794842.
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碩士國立臺灣科技大學
機械工程系
103
Magnesium and its alloys are used in a broad range of applications including automobile, aerospace, communications and computer components owing to their excellent physical and mechanical properties, such as low density, high specific strength, good cast and weld ability, excellent electrical and thermal conductivity, high dimensional stability, and good electromagnetic shielding characteristics. Unfortunately, magnesium alloys possess lower corrosion resistance, especially in acidic environments and salt-water conditions. The ability to increase the corrosion resistance of magnesium and its alloys is crucial to increase the range of applications. To improve the fault, it is important to impart a high corrosion resistance without losing the superior physical and mechanical properties. This study focused on the development of atmospheric pressure plasma jet (APPJ) system using tetraethoxysilane (TEOS)/O2 plasma under atmospheric pressure to deposit SiOx films on the surface of magnesium alloys in order to improve the resistance to corrosion. The material characterization results using X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy indicated that with increased O2 carried gas, the deposited thin films by APPJ were of inorganic SiOx nature. The potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) measurements show that SiOx films coated on AZ91D alloys have more positive corrosion potential and lower corrosion current density than AZ91D substrates, indicating the corrosion resistance of AZ91D can be improved by depositing SiOx film on its surface. Finally, inorganic SiOx film at an O2 carrier gas flow rate of 1800 sccm after immersion in 3.5 wt.% NaCl solution for 72 h showed the better corrosion resistance than AZ91D alloy. The APPJ-deposited SiOx films represent an interesting alternative for improving the anti-corrosion performance of various materials in a cost-effective approach. Keywords: magnesium alloys, Atmospheric pressure plasma deposition technique, inorganic-like silicon oxide (SiOx) thin films, anti-corrosion layers
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Wen, Sheng-Wen, and 溫盛文. "Structural characterization of ZnO/ZnS core-shell nanostructures deposited at atmospheric pressure using DEZn, N2O and DTBS." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/54299067500361361583.
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碩士國立中興大學
物理學系所
104
In this thesis, ZnO nanowires and radial ZnO/ZnS core-shell nanostructure arrays were deposited at atmospheric pressure in a temperature range of 300 ~ 600 oC with diethylzinc (DEZn), nitrous oxide (N2O) and ditert-butylsulfide (DTBS) precursors serving as sources of Zn, O and S elements in the ZnO nanowires and radial ZnO/ZnS core-shell nanostructures. The physical properties of radial ZnO/ZnS core-shell nanostructures were characterized using θ-2θX-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and photoluminescence spectroscopy (PL). It was found that both ZnO and ZnS were wurtzite structure in nature based upon HRTEM investigations. Moire fringes were identified in the radial ZnO/ZnS core-shell nanostructure with a good agreement in the lattice mismatch between ZnO and ZnS in the pseudomorphic ZnO/ZnS core-shell nanostructure. Finally, a slight red-shift in the near band edge (NBE) emissions of the RT PL of the ZnO/ZnS core-shell nanostructures was observed.
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Hsu, Ming-Yi, and 徐明頤. "The study on the silicon dioxide deposited by Atmospheric-Pressure Plasma Technology for Organic Thin-Film Transistor application." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/56314580731999176885.
Full textAbstract:
碩士國立交通大學
電子工程系所
96
We have successfully fabricated pentacene-based organic thin film transistor at a low temperature process with silicon oxide as a gate dielectric deposited by atmospheric-pressure plasma technology (APPT). The advantage of the atmospheric-pressure plasma technology is that it needn't vacuum and at general room temperature to deposit insulator. This merit happen to suits the organic thin film transistor the low temperature system regulation condition. In this article we will study the characteristic of gate silicon oxide which is deposited by atmospheric-pressure plasma technology on the organic thin film transistor. We make use of metal - insulator - metal structure to probe into leakage current of the gate silicon oxide deposited by APPT, and we obtain the lower leakage current of gate dielectric after plasma treatment. In the research, the organic thin film transistor can operate at the voltage less than - 3 volts, and the low operation voltage and low leakage current properties are required in portable applications. In this article we can observe the OTFT characteristic on silicon oxide deposited by APPT. The field-effect transistor has a threshold voltage less than -1V, the mobility of 0.5-0.8 cm2/Vs and on/off ratio about 103.
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Chen, Hsin-Ting, and 陳信廷. "The Study of N2 Plasma Treatment on ZrO2 High-Gate Dielectric of TFTs with Atmospheric Pressure-PECVD Deposited IGZO Channel." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/67397978836800817772.
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碩士國立交通大學
電子工程學系 電子研究所
102
In the past three years, amorphous In-Ga-Zn-O (IGZO) thin film transistors have attracted attention that compared with the conventional a-Si:H TFTs, due to its better field-effect mobility (>10 cm2/V．S), larger Ion/Ioff ratio (>106), smaller subthreshold swing (SS) and better stability against electrical stress. Besides, compare with low temperature ploy-Si (LTPS) TFTs, the a-IGZO TFT do not need high temperature process to recrystallize and activate the dopant. Furthermore, the a-IGZO TFTs have low process temperature, high transmittance that can be applied to fabricate the full transparent TFT on flexible substrate. In this investigation, we used atmospheric-pressure PECVD (AP-PECVD) to deposit our IGZO active layer. With AP-PECVD, we could deposit IGZO thin film without vacuum system, thus, it could lower our cost, improved the throughput, and applied to large area manufacturing. As the scaling to Moore’s law, it is terrible that gate oxide is so thin (1.4nm) which caused an intolerable gate leakage due to direct tunneling current. We use the high- material ZrO2 as our oxide to achieve the thinner EOT (4.05nm) and high on current but not degrade the leakage current. Furthermore, the post N2 plasma treatment on ZrO2 oxide can modify the physical and electrical properties, such as RMS, leakage current, the formation of interfacial layer, et al. We could use the modified ZrO2 thin film which shows better electrical properties as the a-IGZO TFT oxide. Thus, the a-IGZO TFT will exhibits better electrical characteristics. Successfully, we fabricated a-IGZO TFT with AP-PECVD using ZrO2 high-k dielectric. It exhibits comparable mobility of 11.4 cm2/V•S, VT of 0.05 V, subthreshold swing of 182 mV/decade, Ion/Ioff is 2.6×106. With the post N2 plasma treatment on ZrO2 oxide, the a-IGZO TFT exhibits higher mobility of 18.2 cm2/V•S, VT of 0.1 V, lower subthreshold swing of 155 mV/decade, higher Ion/Ioff of 1.49×107.
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Lin, Yi-Jyun, and 林怡君. "Study of Ag-CeO2 Composite Cathode Films Deposited by Atmospheric Pressure Plasma Jet for Intermediate Temperature Solid Oxide Fuel Cells." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/b3nn5c.
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碩士國立臺灣科技大學
機械工程系
105
As compared to the conventional plasma process, the atmospheric pressure plasma jet is an advanced innovative plasma technology. It offers oxidizing species to atomize the metal into droplets under atmospheric environment, because of it does not require any vacuum system. It is a green technology, accompanying with a simple ion reduction reaction process without the use of excessive chemicals. Therefore, Ag-CeO2 composite cathode films deposited by atmospheric pressure plasma jet for intermediate temperature solid oxide fuel cells in this study. According to the results, it’s indicated that the Ag-CeO2 composite cathodes with spherical particles are no found the secondary and impurity phase. The Ag-CeO2 composite cathode film electrochemical performance can be known by electrochemical measurement. The AC64 composite cathode with maximum current density (550.23 mA/cm2) and power density (256.77 mW/cm2) was operated at intermediate and low temperature (400-500oC). Then, the AC28 composite cathode was operated at intermediate temperature (500-600oC), and the result could get the maximum current density (907.18 mA/cm2) and power density (703.28 mW/cm2). Therefore, there was a good electrochemical performance at intermediate temperature in AC64 and AC28 composite cathodes material deposited by atmospheric pressure plasma jet.
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Chi, Chia-Wei, and 吉家威. "Investigation on Thin-Film-Transistors with Zinc-Oxide Active Layer Deposited by Atmosphere–Pressure Plasma Jet." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/94943208221372027043.
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碩士國立交通大學
電子研究所
99
In this thesis, we have successfully developed a high performance thin film transistor (TFT) with zinc oxide active layer deposited by atmosphere pressure plasma (APP) jet. Zinc oxide films show strongly preferred (002) orientation in XRD analysis. Zinc oxide films have over 80％ transmittance of visible light and band gap energy 3.25eV. Therefore zinc oxide films deposited by APP jet are suitable for transparent devices. Wide band gap can release the issue of photo-excited leakage current. At first, we fabricated TFTs on silicon substrate. Experimental parameters of APP jet which we tested and compared including thickness of active layer, hot plate temperature, carrier gas, and main gas. We have developed high performance devices with an on/off ratio of 2.3×107 ,a saturation mobility of 3.21cm2 /Vs, a threshold voltage of 27.3V, a gate voltage swing of 3.83 V/decade. In this thesis, several material analysis techniques, such as XRD, SEM, and PL were utilized to discussing the crystallization, grain size, and surface morphology of ZnO films. Electrical characteristics and conduction mechanisms of ZnO TFTs were also investigated by I-V characteristic analysis. We have fabricated TFTs successfully with ideal experimental parameters on glass substrate. It can prove that our experiments are feasible for real and mass manufacturing in AMOLED or AMLCD. The threshold voltage becomes lower from 27.3V to 11.8V because the hydrogen in gate insulator SiN：H would diffuse to active layer as donors.
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Wu, Yung-Mao, and 吳永茂. "Low Temperature Processes of Organic Thin-Film Transistor with Gate Dielectric of Silicon Dioxide Deposited by Scanning Atmospheric-Pressure Plasma Technology." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/h46c46.
Full textAbstract:
碩士國立交通大學
電機學院微電子奈米科技產業專班
96
We have successfully fabricated pentacene-based organic thin film transistor at a low temperature process with silicon oxide as a gate dielectric deposited by atmospheric-pressure plasma technology (APPT). The major merit of scanning atmospheric-pressure plasma technology was low deposition temperature at one standard atmosphere which was suitable for the application of flexible electrons. The organic thin film transistor demonstrated in this study could operate at the voltage less than -5V and the leakage current of silicon oxide dielectric with MIM structure is about 9×10-8A/cm2 at 0.5 MV/cm. The low operation voltage and low leakage current properties are required in portable applications. Leakage current of not define pentacene region is higher than define pentacene region. And leakage current of have HMDS is higher than not have HMDS.
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MING, CHEN SHIH, and 陳世明. "The effects of the air / N2 atmospheres on the hot corrosion behavior of Fe-(Cr) alloys with NaCl deposit at 850℃." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/93185177282123010989.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
91
The purpose of this study is to investigate the effects of alternative air/N2 atmospheres on the hot corrosion behavior of four commercial steels (SB450, STPA24, STPA26 and 430SS) with NaCl deposit. Corrosion tests carried out at 850℃ with a const flow-rate of 600 mL/min. In the air atmosphere, the results showed that the metal loss decreased with increasing chromium content and the SB450 has the greatest metal loss among four alloys studied. The scales formed on A24 and SB450 were triple layer consisting of Fe2O3, Fe3O4, and FeO from the outer to the inner layer. The outer layer scale of A24 was always fragile while the inner layer showed laminated structure which parallel led to the surface of the steel. The high-Cr-content alloys (A26 and 430SS) formed an outer layer of iron oxide and an inner layer of chromina. The low-Cr-content alloys (A24 and SB450) exist FeO in the test temperature through the observation of quenched specimen, but it disappear after air-cooling. In the N2 atmosphere, oxychlorination was not occurred, and all specimens only had slight metal loss. The chromina merely formed on the high chromium content alloys (A26 and 430SS) due to the low dissociation pressure of oxygen.
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葉芊吟. "Effect of heat treatment under controlled atmosphere on the properties of ZrN film deposited by HCD ion plate." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/4pfyvz.
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碩士國立清華大學
工程與系統科學系
92
Heat treatment processes were applied to enhance the characteristics of ZrN thin films. In this study, ZrN films were deposited on AISI D2 steel using a hollow cathode discharge ion-plating (HCD-IP) technique. Heating environment, including air, Ar/H2, and Zr and Ti getters were discussed with thermodynamic and kinetic analysis. The specimens were heat-treated at 700℃ for 1 hour under optimal atmosphere to reduce oxidation of the thin films. The microstructure, resistivity and packing factor of the heat-treated ZrN thin films were not significantly changed. However, the surface grain size was enlarged and crystalline improved. Preferred orientation of (111) was enhanced after heat treatment. Roughness of the annealed specimens was slightly degraded compared with as-deposited samples. The hardness decreased 26~38 %, this is to be understood that heating reduced the strength of the grain boundary. This also could be attributed to the reduction of defects. The residual stress of the specimens subjected to 700℃ heat treatment was relieved 8~24 % that could be due to the better crystallinity. Corrosion resistance became better after heat treatment; it was confirmed both in salt spray and potentiodynamic scanning.
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Yu, Kae Jy, and 虞凱之. "Effect of heat treatment under controlled atmosphere on the properties of TiN film deposited by unbalaced magnetron sputtering." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/62746948481837567329.
Full textAbstract:
碩士國立清華大學
工程與系統科學系
91
Heat treatment processes were widely applied to enhance the characteristics of TiN thin films. TiN films were deposited on Si wafer using an unbalanced magnetron sputtering technique. Heat-treated environment, including air, Ar/H2, and Ti getter were discussed with thermodynamic and kinetic analysis. The specimens were heat-treated at 500 and 700℃ for 1 hour under optimal atmosphere to reduce the oxidation of the thin films. After heat treatment, the microstructure, resistivity and packing factor of the TiN thin films were not significantly changed. However, the surface grain size was enlarged and crystallization improved. The (200) preferred orientation was more distinct at 700℃ than 500℃ with thinner thickness. (111) texture coefficient was enhanced at both heat-treated temperature. The hardness and roughness of the specimens after annealing were slightly degraded compared with as-deposited sample. This could be attributed to the relaxation of defect structures, about 40% at 500℃ and almost 100% at 700℃. The residual stress of the specimens after 700℃ heat-treated was transformed from compressive to tensile stress that could be due to the smaller thermal expansive coefficient of Si substrate.
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Chen, Chien-Yuan, and 陳健源. "Effects of Composition on Electrical Properties of Amorphous In-Ga-Zn-O Films Deposited Using Atmospheric Pressure Plasma Jet and Post Laser Annealing." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/25393871774700912508.
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碩士國立交通大學
電子工程學系 電子研究所
102
Silicon dioxide (SiO2) has been gate dielectric because of its physical and electrical properties on silicon substrate. But gate leakage current becomes higher when shrinking of the gate length and gate dielectric thickness. Using high dielectric constant material for gate dielectric instead of SiO2 will solve the problem of the gate dielectric thickness. The oxide-based thin film transistors have good electrical properties and high transparency. Amorphous indium gallium zinc oxide (a-IGZO) has advantages of relatively high electron mobility and good chemical stability. In this thesis, new process technology is developed to deposit IGZO films. Atmospheric pressure plasma jet (APPJ) is proposed to fabricate IGZO thin film transistors. Also, water-based metal salt solution, which is an eco-friendly precursor, is adopted, and the thin film can be deposited in atmospheric environment. First, HfO2 and ZrO2 were deposited to fabricate capacitor and IGZO TFTs. According to the experience, we discover that the annealing temperature 500°C has the best condition because of higher capacitance and lower leakage current. Then we fabricated TFTs using IGZO as active channel layer. Many approaches have been studied to improve electrical performance. The channel composition of the IGZO has a large impact on device. The atomic mole ratio of In:Ga:Zn=1:1:1,1:1:2, and 3:1:2 were used as channel layer. The atomic mole ratio of In:Ga:Zn=1:1:2 exhibit a excellent electrical performance. The good electrical characteristics were achieved, including a VT of 0.628V, a subthreshold swing (SS) of 0.365 V/dec, a mobility of 19.8 cm2/V-s and a large Ion/Ioff ratio of 7.34x106. Finally, we investigate the effect of laser annealing on the IGZO TFTs. Because laser annealing can raise the temperature for a short period at a precise position, and can reduce the charge trapping in the gate insulator or the channel/insulator interface. The results show the leakage current of TFTs were all decreased. The molar ratio of In:Ga:Zn=1:1:2 has the best electrical performance with high mobility of 14.36 cm2/V-s, a threshold voltage of 0.16, subthreshold swing (SS) of 0.286 V/dec, and an on/off current ratio of 6.34×107.
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Liao, Yen-Kai, and 廖彥凱. "Studying the electric characterization and surface morphology of silicon dioxide deposited by atmosphere-pressure plasma jet with different precursors." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/33960430734506176071.
Full textAbstract:
碩士國立交通大學
電機學院微電子奈米科技產業專班
98
The semiconductor industry widely use silicon dioxide on devices, including gate insulator and field oxide, but the glass and plastic substrate of photoelectric undertaking can’t endure high temperature such as thermal oxidation. We must use low-temperature process of PECVD to deposit silicon dioxide. With the area of display increase day by day, we have to design larger vacuum chamber and associated pumping system but the cost of equipment will increase. The atmospheric-pressure plasma system has the advantage of low cost, high processing speed, and simple system with no vacuum equipment. In this experiment, we deposited silicon dioxide thin films by atmosphere-pressure plasma jet with different precursors including HMDSN and HMDSO. We vary the parameters of Ar flow rate, substrate temperature, and main gas in order to investigate the electric characterization and surface roughness. When we decrease Ar flow rate and increase substrate temperature to 150 °C respectively. The leakage current of silicon dioxide thin films deposited by atmosphere-pressure plasma jet with HMDSN can attempt to 10-7 (A/cm2) at 0.5 MV/cm, which may be applied for gate insulators of OTFTs. And the film is hydrophobic with 63 ° contact angle, by which can increase the adhesion of organic active layer. Besides, as we increase Ar flow rate, decrease substrate temperature, and increase the proportion of oxygen respectively. All above can increase surface roughness which may be applied for solar cell as anti-reflection layer, which could reduce multi-processes.
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Lan, Wei-Che, and 藍偉哲. "The optoelectronic properties of amorphous IGZO films deposited by co-sputtering and treated by atmosphere plasma and vacuum annealing." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/79008638265423060497.
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碩士崑山科技大學
電機工程研究所
101
In this study, we used RF magnetron co-sputtering to grow IGZO films on glass substrates. The films were processed by changing work pressure, process time, and RF power to get appropriate properties of films. After deposition, the IGZO samples were treated in various atmosphere plasma and vacuum annealing. After the atmosphere plasma and vacuum annealing treatment, the IGZO properties could further improve such as transmittance and resistivity. According to the experiment results, better properties of IGZO films were obtained at lower work pressure. When the deposition time is too long the electrical and optical properties will become worse. The resistance and transmittance of films were improved with increasing the gallium-doped as well as increasing the RF power. For the Ga2O3 power of 100W, the best properties of the resistivity of 1.17×10-3 Ω-cm, carrier concentration of 2.01×1020 cm-3, mobility of 26.5 cm2/Vs and average transmittance of 90.4 % were obtained at the process condition which was carried out at that the work pressure is 3mtorr, the IZO power is 125W and, the deposition time is 20min and the substrate temperature is set at room temperature. For the Ga2O3 power of 30W, we can get the best properties with Ga2O3 doped. The best properties show the resistivity of 7.95×10-4 Ω-cm, the carrier concentration of 1.8×1020 cm-3, the mobility of 43.6 cm2/Vs and the average transmittance of 87.7 %. In vacuum annealing, we got the best properties of films at temperature of 400℃ and processing time of 60min. The heating effect by vacuum annealing into IGZO film was eliminate defects and ion diffusion in high temperature, therefore the properties were improved such as the resistivity of 3.621×10-4 Ω-cm, the carrier concentration of 4.038×1020 cm-3, the mobility of 42.7 cm2/Vs and the average transmittance of 90.36 %. In different atmosphere plasma, we got the transmittance increased without changing the resistivity on Argon plasma, and the transmittance was changed a little. The results show that the resistivity was reduced in hydrogen plasma, transmittance and resistivity but changes a little in nitrogen and argon plasma.
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Tsai, Kun-Hao, and 蔡堃濠. "Investigation of the thin silicon oxide deposited with different basic process parameters of atmospheric-pressure plasma jet at low temperature for OTFTs Gate insulator." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/74134644128905633251.
Full textAbstract:
碩士國立交通大學
電機學院微電子奈米科技產業專班
98
Low operation voltage organic thin film transistors (OTFTs) were successfully fabricated with top contact structure at low fabrication temperature. The thin gate dielectric of OTFTs were deposited by atmospheric pressure plasma jet at the substrate temperature about 150℃and under atmospheric pressure. The environment of processes would significantly improve the abilities of large area application for display and decrease the cost of instruments. We found that the quality of silicon oxide deposited by atmospheric pressure plasma jet strongly depended on the main gas, the gap distance between plasma nozzle and surface of the device, and the Ar flow rate even influenced the deposition rate. Due to the improvement of gate insulator quality, good electrical characteristics of OTFTs can be obtained, such as carrier mobility as large as 0.66 cm2/ V•s, operation voltage as low as -2 V, and subthreshold swing as low as 0.7 V/dec.
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Chen, Wei-Chiang, and 陳偉強. "Study on the opto-electrical characterization and material analysis of gallium doped zinc oxide film deposited by atmosphere-pressure plasma jet." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/60589195702185120221.
Full textAbstract:
碩士國立交通大學
電機學院微電子奈米科技產業專班
99
Ga doped Zinc oxide (GZO) films have been deposition by the atmospheric pressure plasma chemical vapor deposition (APPCVD) onto preheated glass substrates using Zn(NO3)2 and Ga(NO3)2 as precursors for Zn and Ga ions, respectively. The effect of the Ga dopant concentration , substrate temperature, gap distance, scan times, carrier gas flow rate, and Zn(NO3)2 concentration on the physical properties of the ZnO and GZO thin films was analyzed. The effect on the structural, morphological, optical, optical and electrical properties of APPCVD ZnO thin films were investigated using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), photoluminescence (PL), scanning electron microscopy (SEM), atomic force microscopy (AFM), spectrophotometer, Hall measurement and four point probe. According to the above analysis the best deposition parameters of GZO thin film can be determined. XRD studies reveal that films are polycrystalline with hexagonal (wurtzite) crystal structure. The thin films were mainly oriented along the (002) plane. The best sample with a resistivity of 8x10-4 cm and a transmittance of over 80% in visible region was achieved. This result makes APPCVD GZO thin film potentially applicable as transparent electrode in opto-electrical devices.