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1
Fernandes, Valéria Cristina. "Estudo dos processos de eletrodeposição de filmes finos de Se, ZnSe e PbS." Universidade Federal de São Carlos, 2008. https://repositorio.ufscar.br/handle/ufscar/6099.
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This work describes studies on the underpotential deposition (UPD) of selenium, zinc, as well for Zn/Se systems deposited on polycrystalline Pt electrodes in acid solutions. The effects of Zn presence in the Se dissolution process were also investigated in the UPD and bulk potential range, 0.6 and 0.03 V respectively. The measurements were carried out using cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). Furthermore Lead sulfide (PbS) multilayers were grown on a single crystal Ag(111) substrate by Electrochemical Atomic Layer Epitaxy (ECALE) method. For Zn UPD in sulfuric acid, two different processes were observed, which are attributed to the dissolution of submonolayer of Znads and H-atoms adsorbed on the electrode surface. For Se UPD was observed that hydrogen desorption were completely inhibited indicating that Se film recovered the Pt surface. The deposition of UPD Se in perchloric acid solution showed the transference of 4 electrons with 1.4 and 1.12 active sites of Pt occupied by 1 Se ad-atom in the UPD and bulk potential range, respectively. In the evaluation of the Se monolayers dissolution process formed at 0.03 V during 2000 s a process not mentioned in the literature it was observed which was evaluated by the technique MECQ. The experimental results obtained by this technique allowed to end that the dissolution process occurred by two stages, and the first involved the participation of 6e-. The dissolution mechanism with 6e- happens with the participation of water in the dissolution process of Se, leading to the formation of an oxygenated selenium compound which in next step undergo slow oxidation and is dissolved as soluble Se(VI) species. Then the total dissolution process of Se occurs in a six-electron transfer reaction. For Se deposition in the Zn presence the dissolution charges associated with Se UPD increase, indicating that the presence of Zn favors the deposition of UPD Se. In the case of PbS multilayers on Ag (111) the voltammetric analysis of the first PbUPD and SUPD peaks indicates a mechanism of two-dimensional growth, which is consistent with epitaxial growth. Electrochemical stripping measurements indicate that the amount of Pb and S deposited in a given number of cycles is a function of the number of cycles employed, again suggesting a layer-by-layer growth. This result indicates that the amount of Pb and S in these films corresponds to the stoichiometric 1:1 ratio, indicating the formation of a compound.
Este trabalho descreve os estudos da deposicao em regime de subtensao (DRS) de Se, Zn, assim como para sistemas Zn/Se depositados sobre eletrodos policristalinos de Pt em solucoes acidas. Os efeitos da presenca de Zn no processo de dissolucao de Se tambem foram investigados em uma regiao de potenciais de DRS e deposicao massiva 0,6 V e 0,03 V, respectivamente. As medidas foram realizadas usando voltametria ciclica e microbalanca eletroquimica de cristal de quartzo (MECQ). Alem disso, multicamadas de sulfeto de chumbo (PbS) foram crescidas sobre substrato de Ag(111) utilizando o metodo de deposicao eletroquimica de camadas atomicas epitaxiais (ECALE). Para a DRS de Zn em meio de acido sulfurico dois processos distintos foram observados os quais foram atribuidos a submonocamadas de Znads e atomos de H adsorvidos sobre a superficie do eletrodo. Para a DRS do Se observou-se a inibicao completa da dessorcao de hidrogenio o que indicou recobrimento total da superficie de Pt por ad-atomo de Se. A deposicao de Se em meio de acido perclorico mostrou a transferencia de 4 eletrons com 1,4 e 1,12 sitios da Pt ocupados por cada ad-atomo de Se, em potenciais de deposicao em DRS e sobretensao, respectivamente. Na avaliacao do processo de dissolucao das monocamadas de Se formadas a 0,03 V e por um tempo de deposicao de 2000 s um processo nao mencionado na literatura foi observado o qual foi avaliado pela tecnica MECQ. Os resultados experimentais obtidos por esta tecnica permitiram concluir que o processo de dissolucao do Se ocorria por duas etapas, sendo que a primeira envolvia a participacao de uma 6 eletrons e a segunda de 4 eletrons. O mecanismo de dissolucao com 6 eletrons ocorre com a participacao de agua no processo de dissolucao do Se, levando a formacao de compostos de Se oxigenados, os quais em uma etapa posterior sofrem uma oxidacao lenta e se dissolvem como especies soluveis de Se(VI). Entao o processo total de dissolucao de Se ocorre em uma reacao de transferencia de 6 eletrons. Ja para a deposicao de Se na presenca de Zn pode-se concluir, devido ao aumento da carga de dissolucao da DRS de Se, que a presenca de Zn favorece o processo de deposicao do Se. No caso das multicamadas de PbS o estudo voltametrico das primeiras camadas de Pb DRS e S DRS indicam um mecanismo de crescimento bidimensional, que e consistente com o crescimento epitaxial. As cargas medidas no processo de dissolucao das camadas indicaram que a quantidade de Pb e S depositados para um dado numero de ciclos e uma funcao do numero de ciclos realizados, sugerindo novamente um crescimento camada por camada Este resultado sugere que a quantidade de Pb e S nos filmes possuem uma relacao estequiometrica de 1:1, indicando a formacao de um composto.
2
Yeo, Philip Sinclair. "Role of gallium precursors in atomic layer epitaxy of GaAs." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0019/MQ51515.pdf.
Повний текст джерела
3
Gong, Yukun. "Electrochemical Atomic Layer Etching of Copper and Ruthenium." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1625783128128316.
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4
Arès, Richard. "Growth mechanisms of atomic layer epitaxy studied in situ by reflectance difference spectroscopy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24289.pdf.
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Venkatraman, Kailash. "Electrochemical Atomic Layer Deposition of Metals for Applications in Semiconductor Interconnect Metallization." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1543839404490434.
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6
Watanabe, Joy Kimi. "Silicon preparation techniques for nucleation and growth studies of zinc sulfide deposited by atomic layer epitaxy." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185938.
Повний текст джерелаАнотація:
Zinc sulfide with a direct bandgap of 3.6 eV is a potential candidate as blue-light emitting diodes and lasers. Initial growth of ZnS on Si(100) substrates by atomic layer epitaxy (ALE), a deposition technique in which film growth ideally proceeds in a 2-dimensional, layer-by-layer manner, has been investigated. The interaction between the first layer of atoms of the film and the substrate surface initiates film growth and affects the resulting structure. Work has focused on the effects of surface composition, (particularly on the role of sulfur) on the initial growth of ZnS on Si(100), and thus the chemical composition must be well controlled and characterized. Three methods have been used to process Si(100) substrates. The first was a wet chemical clean with either HF or H₂O passivation followed by a low temperature (700-800°C) anneal in UHV. The second processing method was ion sputter cleaning with a post-sputter anneal at 800-900°C. The third technique irradiated substrates held in UHV with a beam from a KrF excimer laser. Initial layers of ZnS (from Zn and H₂S) were then deposited onto processed substrates. Samples were characterized by in-situ angle resolved x-ray photoelectron spectroscopy (ARXPS) to determine the chemical composition of the surface and also the coverage and thickness of contamination and film layers. The main impurities on the surface were oxygen and carbon. The first two processing techniques had difficulty in either eliminating those impurities or caused additional contamination. Elimination of the impurities was achieved using excimer laser irradiation with a pre-dose of reactive gas. The substrate surface could also be chemically modified in a controlled manner using excimer laser irradiation. Deposition studies of initial sulfur and zinc layers onto the processed substrates determined the temperature during ALE growth should be held at 250-310°C. Uniform coverage of both sulfur and zinc was difficult to obtain, but experiments indicated sulfur adhesion improved with the presence of oxygen, and zinc adhesion improved when oxide or sulfide layers were present on the surface.
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Bonnet, Nicéphore. "A multiscale study of atomic interactions in the electrochemical double layer applied to electrocatalysis." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/76914.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 171-182).
This work is an integrated study of chemical and electrostatic interactions in the electrochemical double layer, and their significance for accurate prediction of reaction kinetics in electrocatalysis. First, a kinetic model of the oxygen reduction reaction (ORR) on platinum, in connexion with first-principles techniques, is developed to illustrate that a self-consistent description of kinetics and reactant coverages on the surface can help to propose new mechanisms when energy prediction and experimental uncertainties still prevail. ORR kinetic limitation is often rationalized in terms of surface poisoning by parallel reactions, namely water oxidation, and/or as a result of the demanding requirements of Sabatier's principle. The sensitivity analysis presented here suggests that additional mechanisms may have to be considered, in particular self-poisoning by transient 02 dissociation in certain regimes. A common assumption of kinetic studies is that the only effect of electrode bias is to modify the electron chemical potential. To refine our understanding of bias effects in the double layer, a correction code applied to plane-wave DFT techniques is used to realistically simulate an electrochemical setup under potential control as an electrode with variable explicit charge screened by ions in solution. The scheme is first used to shed light on the nature of the stretching frequency shift of CO on Pt(1 11) as a function of electrode potential. It is concluded that the Stark effect interpretation is correct, and more generally, that electrochemistry on metal surfaces may often be correctly described in terms of perturbation theory. Then, hydrogen under-potential deposition on platinum is computed as a function of pH. It is shown that modification of the surface dipole by hydrogen electrosorption couples with the surface charge to make the adsorbant chemical potential pH-dependent. This observation is related to the concept of electrosorption valency. The octahedric-to-cubic nanoparticle shape transition resulting from hydrogen adsorption upon cathodic sweep is then predicted to be more pronounced in alkaline media. Inclusion of surface dipole effects is therefore relevant for surface stability and shape-dependent electroactivity. Third, the correction scheme is applied to develop a model of water dielectric saturation in the strong fields of the double layer. The water molecule dipole is computed in real space and Monte-Carlo simulation techniques are performed for the statistics of proton arrangement. DFT is seen to overestimate the permittivity of ice, confirming the difficulty of water simulation at the first-principles level. However, saturation effects are believed to be qualitatively captured and their influence on reaction kinetics in the double layer from the Frumkin effect is assessed. The impact is rather moderate with at most a factor of 3 in exchange current predictions. Finally, DFT occasional errors in chemisorption energies remain an important drawback for heterogeneous catalysis studies. Here, the vdW-DF functional for inclusion of long-range, dispersion interactions is tested on the prediction of CO adsorption on transition metals. Observed improvement on binding energies and adsorption site ordering comes at the expense of the correct description of metal energetics, suggesting the need for alternative schemes in this case. In conclusion, the purpose of this work is to help the design of electrocatalysts by providing a framework to assess chemical and electrostatic contributions to the kinetics, informed by the complexity and uncertainties attached to the surface and double layer structure.
by Nicéphore Bonnet.
Ph.D.
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Xaba, Nqobile. "Development of Anode Materials Using Electrochemical Atomic Layer Deposition (E-ALD) for Energy Applications." University of the Western Cape, 2018. http://hdl.handle.net/11394/6390.
Повний текст джерелаАнотація:
Philosophiae Doctor - PhD (Chemistry)Nanomaterials have been found to undeniably possess superior properties than bulk structures across many fields of study including natural science, medicine, materials science, electronics etc. The study of nano-sized structures has the ability to address the current world crisis in energy demand and climate change. The development of materials that have various applications will allow for quick and cost effective solutions. Nanomaterials of Sn and Bi are the core of the electronic industry for their use in micro packaging components. These nanomaterials are also used as electrocatalysts in fuel cells and carbon dioxide conversion, and as electrodes for rechargeable sodium ion batteries. There are various methods used to make these nanostructures including solid state methods, hydrothermal methods, sputtering, and vacuum deposition techniques. These methods lack the ability to control the structure of material at an atomic level to fine tune the properties of the final product. This study aims to use E-ALD technique to synthesis thin films of Sn and Bi for various energy applications, and reports the use of E-ALD in battery applications for the first time. Thin films were synthesised by developing a deposition sequence and optimising this deposition sequence by varying deposition parameters. These parameters include deposition potential, and concentration of precursor solution. The thin films were characterised using cyclic voltammetry, linear sweep voltammetry, chronoamperometry for electrochemical activity. These were also characterised using scanning electron microscope for morphology, x-ray diffraction for crystal phases, energy dispersive spectroscopy for elemental mapping, and focused ion beam scanning electron microscope for thickness. The elemental content was analysed using electron probe micro analysis and inductively coupled plasma mass spectrometry. The electrochemical impedance charge and discharge profile were used for electrochemical battery tests.
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Mkhohlakali, Andile Cyril. "Development of nanostructured electrocatalysts using electrochemical atomic layer deposition technique for the direct liquid fuel cells By." University of Western Cape, 2020. http://hdl.handle.net/11394/7346.
Повний текст джерелаАнотація:
Philosophiae Doctor - PhDThe depletion of fossil fuel resources such as coal and the concern of climatic change arising from the emission of greenhouse gases (GHG) and global warming [1] lead to the identification of the 'hydrogen economy' as one of the renewable energy sources and possible futuristic energy conversion solution. Sources of hydrogen as fuel such as water through electrolysis and liquid organic fuel (Hydrogen carriers) have been found as potential game-changers and received increased attention, due to its low-carbon emission.
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Trombley, Jeremy Brian. "Studies of Electrochemical Charge Transfer between Metals and Aqueous Solutions Using Atomic Force Microscopy." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1386048981.
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Törndahl, Tobias. "Atomic Layer Deposition of Copper, Copper(I) Oxide and Copper(I) Nitride on Oxide Substrates." Doctoral thesis, Uppsala University, Department of Materials Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4651.
Повний текст джерелаАнотація:
Thin films play an important role in science and technology today. By combining different materials, properties for specific applications can be optimised. In this thesis growth of copper, copper(I) oxide and copper(I) nitride on two different substrates, amorphous SiO2 and single crystalline α-Al2O3 by the so called Atomic Layer Deposition (ALD) techniques has been studied. This technique allows precise control of the growth process at monolayer level on solid substrates. Other characteristic features of ALD are that it produces films with excellent step coverage and good uniformity even as extremely thin films on complicated shaped substrates.
Alternative deposition schemes were developed for the materials of interest. It was demonstrated that use of intermediate water pulses affected the deposition pathways considerably. By adding water, the films are thought to grow via formation of an oxide over-layer instead of through a direct reaction between the precursors as in the case without water.
For growth of copper(I) nitride from Cu(hfac)2 and ammonia no film growth occurred without adding water to the growth process. The Cu3N films could be transformed into conducting copper films by post annealing. In copper growth from CuCl and H2 the water affected film growth on the alumina substrates considerably more than on the fused silica substrates. The existence of surface -OH and/or -NHx groups was often found to play an important role, according to both theoretical calculations and experimental results.
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Melendez-Ceballos, Arturo. "Adéquation de nouvelles compositions d'électrolytes et de revêtements protecteurs nanostructurés de la cathode pour les piles à combustible à carbonates fondus TiO2 protective coating processed by Atomic Layer Deposition for the improvement of MCFC cathode Electrochemical properties of Atomic layer deposition processed CeO2 as a protective layer for the molten carbonate fuel cell cathode." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066103.
Повний текст джерелаАнотація:
Dans ce travail, nous développons deux grands axes de recherche liés aux carbonates fondus. Le premier est l'optimisation des piles à combustible à base de carbonates fondus, avec deux approches : (i) l'amélioration de la durée de vie de la cathode grâce à des couches ultra-minces d'oxydes métalliques élaborés par la technique de dépôt de couches atomiques; (ii) la modification des électrolytes Li-K et Li-Na par addition de Cs ou de Rb. Le second est consacré à la valorisation du CO2 par sa réduction électrochimique dans les électrolytes à carbonates fondus, où nous analysons la réduction du CO2 par chronopotentiométrie et chronoamperométrie. Finalement, afin de tester les modifications subies par certains des composants analysés dans les deux premières parties, nous avons installé et adapté une configuration de cellule complète couplée à la chromatographie en phase gazeuse. Nous avons obtenu quelques résultats significatifs dans l’ensemble des approches abordées ; en ce qui concerne le point (i), nous avons constaté que TiO2 et CeO2 sont appropriés pour protéger la cathode contre la corrosion sans affecter ses propriétés électrochimiques en réduisant presque de moitié la dissolution du Ni. Les résultats obtenus pour le point (ii) sont également fructueux, car nous avons établi une méthode pour comparer deux électrolytes différents en déterminant les coefficients de diffusion des ions superoxyde et du dioxyde de carbone. Nous avons également comparé les performances de la cathode de NiO dans les électrolytes modifiés avec Cs et Rb. De ces études, nous avons constaté que l'addition de Cs améliore significativement le coefficient de diffusion de CO2 en réduisant la résistance de transfert de charge et la résistance totale à l'électrode, étant l'additif le plus prometteur testé ici. En ce qui concerne la réduction du CO2, nous avons constaté que la réaction implique des espèces adsorbées et instables et se produit en deux étapes à un électron ou une étape à deux électrons ; ainsi, il s’agit très probablement d’un mécanisme de réduction simultanée d’espèces adsorbées et dissoutes. Finalement, nous avons effectué les premiers tests sur cellule complète MCFC dans notre laboratoire, obtenant une performance et une puissance acceptables. Cependant, de petites améliorations sont encore nécessaires pour pouvoir tester les composants modifiés de cellule MCFCIn this work, we develop two major research routes related to molten carbonates. The first one is the molten carbonate fuel cell optimization, with two approaches: (i) cathode lifetime improvement through ultra-thin layers of metal oxides deposited by atomic layer deposition; (ii) Li-K and Li-Na electrolyte modification by Cs or Rb additions. The second one is dedicated to CO2 valorization through its electrochemical reduction in molten carbonate electrolytes, where we analyze CO2 reduction by means of chronopotentiometry and chronoamperometry. Finally, in order to test some of the component modifications described in the two first parts, we installed and adapted a single-cell setup coupled to gas chromatography. We obtained some significant results in all the approaches; concerning point (i), we found that TiO2 and CeO2 are suitable for cathode corrosion protection without affecting the electrochemical properties of the electrode and reducing almost by half the dissolution of Ni. The results obtained from point (ii) are also fruitful, since we established a method for comparing two different electrolytes and obtained the diffusion coefficients of the superoxides and carbon dioxide. We also compared the performance of the state-of-the-art NiO cathode in Cs and Rb modified electrolytes. From these studies, we found that Cs addition improves significantly the CO2 diffusion coefficient and reduces the charge transfer and total resistance at the electrode, being a promising additive. Regarding CO2 reduction, after all the tests performed, we found that the reaction involves adsorbed and instable species and occurs in two one-electron steps or in two-electron unique step; thus, it follows most probably a mechanism of simultaneous reduction of the adsorbed and dissolved species. Finally, we performed the first MCFC single-cell tests in our laboratory obtaining an acceptable cell performance and output power. However, small improvements are still necessary to be able to test MCFC modified components
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Silva, Ricardo Manuel Fonseca Lopes. "Metal oxide/carbon nanotubes heterostructures for electric double layer capacitors." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22962.
Повний текст джерелаАнотація:
Doutoramento em Ciência e Engenharia de MateriaisO presente estudo teve como objetivo principal a elaboração e caracterização de hétero-estruturas hibridas tridimensionais (3D) de nanotubos de carbono alinhados verticalmente e revestidos com óxido de manganês para aplicações em condensadores eletroquímicos como elétrodos livres de aditivos. Numa primeira fase, foram desenvolvidas metodologias para o crescimento de nanotubos de carbono puro e para nanotubos de carbono dopados com azoto, em substratos isoladores e metálicos, por deposição química em fase de vapor. Foi dada especial atenção ao crescimento direto de nanotubos de carbono alinhados verticalmente no substrato metálico (Inconel®600) e sua aplicação em elétrodos livres de aditivos à base de carbono. Posteriormente, foi desenvolvido um processo inovador para a deposição de óxido de manganês (Mn3O4) por deposição por camada atómica para o revestimento de nanoestruturas, como os nanotubos de carbono, para a elaboração de heteroestruturas. Estas foram devidamente caracterizadas como materiais para aplicações em eléctrodos. A eficiência electroquímica dos eléctrodos atinge um máximo para o nanocompósito de nanotubos de carbono puro/óxido de manganês revestidos com 600 ciclos por deposição por camada atómica e apresenta uma capacitância de 78.68 mF cm-2 a 5 mV s-1. Este resultado pode ser atribuído ao efeito cooperativo entre os componentes do nanocompósito e uma utilização eficaz dos materiais ativos. Provou-se que um material nanocompósito que englobe a capacitância da dupla camada elétrica, bem como a estrutura condutora dos nanotubos de carbono e a pseudocapacitância dos óxidos metálicos é de grande interesse devido ao seu mecanismo duplo de armazenamento de carga e as vantagens de cada mecanismo são exploradas nestes novos dipositivos híbridos. Este trabalho foi realizado na Universidade de Aveiro e na Universidade de Humboldt (Berlim), beneficiando das infraestruturas adequadas à execução do trabalho experimental de ambas as instituições e das competências complementares das equipas de investigação associadas. Devido à natureza multidisciplinar da área de investigação onde este doutoramento se insere, a colaboração com outras instituições internacionais valorizaram a discussão dos resultados obtidos e fundamentaram os novos materiais desenvolvidos
The purpose of this work was the elaboration and characterization of hybrid three-dimensional (3D) arrays of vertically aligned carbon nanotubes coated with manganese oxide heterostructures for application as binder-free electrodes in electrochemical capacitors. In the first stage, methodologies to grow pure and nitrogen doped vertically aligned carbon nanotubes arrays on nonmetallic and metallic substrates by thermal chemical vapor deposition have been developed. Particular attention was devoted to obtain vertically aligned carbon nanotubes arrays grown directly on metallic conductive substrates (Inconel®600) and their application in binderfree carbon-based electrodes. Subsequently, as one of the main points of this work, a novel manganese oxide (Mn3O4) atomic layer deposition process has been developed for coating nanostructures, such as carbon nanotubes, for the elaboration of heterostructures which were further used and characterized as electrodes materials. The electrochemical performance of the electrodes reaches a maximum for the pure carbon nanotubes/manganese oxide nanocomposite coated with 600 ALD cycles exhibiting a specific capacitance of 78.68 mF cm-2 at 5 mV s-1. This result could be attributed to the synergetic effect between the components in the nanocomposite and an effective utilization of the active materials. Therefore it was demonstrated that a nanocomposite material comprising electric double layer capacitance together with the conductive framework of the carbon nanotubes and pseudocapacitive metal oxides is of great interest due to its dual charge storage mechanism and the advantages of each mechanism are exploited in these new hybrid devices. This work was carried out at University of Aveiro and at Humboldt-Universität zu Berlin due to complementary avaivable expertises and equipments, and also benefits of several international collaborations due to the multidisciplinar nature of the research field.
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Peng, Chunqing. "Electrostatic layer-by-layer assembly of hybrid thin films using polyelectrolytes and inorganic nanoparticles." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43684.
Повний текст джерелаАнотація:
Polymer/inorganic nanoparticle hybrid thin films, primarily composed of functional inorganic nanoparticles, are of great interest to researchers because of their interesting electronic, photonic, and optical properties. In the past two decades, layer-by-layer (LbL) assembly has become one of the most powerful techniques to fabricate such hybrid thin films. This method offers an easy, inexpensive, versatile, and robust fabrication technique for multilayer formation, with precisely controllable nanostructure and tunable properties. In this thesis, various ways to control the structure of hybrid thin films, primarily composed of polyelectrolytes and indium tin oxide (ITO), are the main topics of study. ITO is one of the most widely used conductive transparent oxides (TCOs) for applications such as flat panel displays, photovoltaic cells, and functional windows. In this work, polyethyleneimine (PEI) was used to stabilize the ITO suspensions and improve the film buildup rate during the LbL assembly of poly(sodium 4-styrenesulfonate) (PSS) and ITO. The growth rate was doubled due to the stronger interaction forces between the PSS and PEI-modified ITO layer. The assembly of hybrid films was often initiated by a polyelectrolyte precursor layer, and the characteristics of the precursor layer were found to significantly affect the assembly of the hybrid thin films. The LbL assembly of ITO nanoparticles was realized on several substrates, including cellulose fibers, write-on transparencies, silicon wafers, quartz crystals, and glasses. By coating the cellulose fibers with ITO nanoparticles, a new type of conductive paper was manufactured. By LbL assembly of ITO on write-on transparencies, transparent conductive thin films with conductivity of 10⁻⁴ S/cm and transparency of over 80 % in the visible range were also prepared. As a result of this work on the mechanisms and applications of LbL grown films, the understanding of the LbL assembly of polyelectrolytes and inorganic nanoparticles was significantly extended. In addition to working with ITO nanoparticles, this thesis also demonstrated the ability to grow bicomponent [PEI/SiO₂]n thin films. It was further demonstrated that under the right pH conditions, these films can be grown exponentially (e-LbL), resulting in much thicker films, consisting of mostly the inorganic nanoparticles, in much fewer assembly steps than traditional linearly grown films (l-LbL). These results open the door to new research opportunities for achieving structured nanoparticle thin films, whose functionality depends primarily on the properties of the nanoparticles.
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Waechtler, Thomas, Shao-Feng Ding, Lutz Hofmann, Robert Mothes, Qi Xie, Steffen Oswald, Christophe Detavernier, et al. "ALD-grown seed layers for electrochemical copper deposition integrated with different diffusion barrier systems." Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-68040.
Повний текст джерелаАнотація:
The deposition of Cu seed layers for electrochemical Cu deposition (ECD) via atomic layer deposition (ALD) of copper oxide and subsequent thermal reduction at temperatures between 110 and 120°C was studied on different diffusion barrier systems. While optimization of the process is required on TaN with respect to reduction and plating, promising results were obtained on blanket PVD Ru. The plating results on layers of ALD Cu with underlying Ru even outperformed the ones achieved on PVD Cu seed layers with respect to morphology and resistivity. Applying the processes to via and line patterns gave similar results, suggesting that a combination of ALD Cu with PVD or ALD-grown Ru could significantly improve the ECD Cu growth.
16
Lindahl, Erik. "Thin Film Synthesis of Nickel Containing Compounds." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-111484.
Повний текст джерела
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Mueller, Steve, Thomas Waechtler, Lutz Hofmann, Andre Tuchscherer, Robert Mothes, Ovidiu Gordan, Daniel Lehmann, et al. "Thermal ALD of Cu via Reduction of CuxO films for the Advanced Metallization in Spintronic and ULSI Interconnect Systems." Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-84003.
Повний текст джерелаАнотація:
In this work, an approach for copper atomic layer deposition (ALD) via reduction of CuxO films was investigated regarding applications in ULSI interconnects, like Cu seed layers directly grown on diffusion barriers (e. g. TaN) or possible liner materials (e. g. Ru or Ni) as well as non-ferromagnetic spacer layers between ferromagnetic films in GMR sensor elements, like Ni or Co. The thermal CuxO ALD process is based on the Cu (I) β-diketonate precursor [(nBu3P)2Cu(acac)] and a mixture of water vapor and oxygen ("wet O2") as co-reactant at temperatures between 100 and 130 °C. Highly efficient conversions of the CuxO to metallic Cu films are realized by a vapor phase treatment with formic acid (HCOOH), especially on Ru substrates. Electrochemical deposition (ECD) experiments on Cu ALD seed / Ru liner stacks in typical interconnect patterns are showing nearly perfectly filling behavior. For improving the HCOOH reduction on arbitrary substrates, a catalytic amount of Ru was successful introduced into the CuxO films during the ALD with a precursor mixture of the Cu (I) β-diketonate and an organometallic Ru precursor. Furthermore, molecular and atomic hydrogen were studied as promising alternative reducing agents.
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Chmela, Ondřej. "Pokovování polyetylentereftalátu mědí a realizace vodivých struktur." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220081.
Повний текст джерелаАнотація:
The content of this master’s thesis are methods of pretreatment and coating of the surface of PET to produce conductive copper structure and quality control. Thesis also includes theoretical analysis of these methods. Physical and chemical techniques of surface pretreatment methods are discussed in the theoretical part as well as methods making surface of substrate conductive, the subsequent galvanic copper plating and quality control of coating and testing of the adhesion between layers. The experimental part focuses on two methods of the polymer material surface pretreatments. The properties of these pretreatments were evaluated by using the atomic force microscopy and detection of surface energy by wetting and contact angle measurements. The surface is making conductive with cathode sputtering and electrochemical coating of copper. Adhesion of layers is tested mainly with scratch test and other methods. The results of these sub-operations are used for the realization of multi-layer conductive structures.
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Mueller, Steve, Thomas Waechtler, Lutz Hofmann, Andre Tuchscherer, Robert Mothes, Ovidiu Gordan, Daniel Lehmann, et al. "Thermal ALD of Cu via Reduction of CuxO films for the Advanced Metallization in Spintronic and ULSI Interconnect Systems." Technische Universität Chemnitz, 2011. https://monarch.qucosa.de/id/qucosa%3A19675.
Повний текст джерелаАнотація:
In this work, an approach for copper atomic layer deposition (ALD) via reduction of CuxO films was investigated regarding applications in ULSI interconnects, like Cu seed layers directly grown on diffusion barriers (e. g. TaN) or possible liner materials (e. g. Ru or Ni) as well as non-ferromagnetic spacer layers between ferromagnetic films in GMR sensor elements, like Ni or Co. The thermal CuxO ALD process is based on the Cu (I) β-diketonate precursor [(nBu3P)2Cu(acac)] and a mixture of water vapor and oxygen ("wet O2") as co-reactant at temperatures between 100 and 130 °C. Highly efficient conversions of the CuxO to metallic Cu films are realized by a vapor phase treatment with formic acid (HCOOH), especially on Ru substrates. Electrochemical deposition (ECD) experiments on Cu ALD seed / Ru liner stacks in typical interconnect patterns are showing nearly perfectly filling behavior. For improving the HCOOH reduction on arbitrary substrates, a catalytic amount of Ru was successful introduced into the CuxO films during the ALD with a precursor mixture of the Cu (I) β-diketonate and an organometallic Ru precursor. Furthermore, molecular and atomic hydrogen were studied as promising alternative reducing agents.
20
CHOLLET, FREDERIC. "Epitaxie à basse température de couches silicium et Si(1-x)Gex : étude par microscopie à force atomique." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10183.
Повний текст джерелаАнотація:
Les couches epitaxiees a basse temperature (<650c) offrent des perspectives interessantes en vue de la fabrication de dispositifs microelectroniques sophistiques, integrant des structures fragiles comme des profils de dopants tres minces ou des films heteroepitaxies metastables. Ces couches doivent etre structuralement parfaites afin d'atteindre les caracteristiques electriques attendues. Ce travail est motive par l'etude de la morphologie de surface de couches epitaxiales de si et si#1#-#xge#x deposees sur si(100) par cvd a basse temperature (550-800c). La caracterisation physique a principalement ete effectuee par microscopie a force atomique (afm). La preparation de surface des substrats avant epitaxie est une etape critique. C'est pourquoi la surface du si(100) a ete etudiee apres nettoyage par voie humide et apres recuit sous hydrogene vis a vis de la nano-rugosite, des terminaisons atomiques et des contaminants adsorbes. Les premiers instants de l'homoepitaxie de si ont ete etudies en detail. Deux modes de croissance (l'un lisse l'autre rugueux) dependant a la fois des parametres de substrat et de depot sont observes. Le mode lisse se caracterise par une croissance en terraces, alors que le mode rugueux correspond a une croissance par facettage. La morphologie de surface resultante a ete reliee a la couverture dynamique en hydrogene du front de croissance. D'autres mecanismes de croissance entrent en jeu dans les films si#1#-#xge#x en raison des contraintes existantes. Des films de si#1#-#xge#x contraints en compression et en tension ont ete etudies. Les films en compression presentent une croissance stranski-krastanov sans defaut permettant une relaxation partielle de la contrainte au travers d'ondulations de surface. Pour les films en tension, la topographie finale depend fortement de la diffusion de surface des ad-atomes.
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Ahmed, Mustafa M. Abdalla. "Alternating-Current Thin-Film Electroluminescent Device Characterization." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-233432.
Повний текст джерелаАнотація:
Jádrem této disertační práce bylo studovat optické a elektrické charakteristiky tenkovrstvých elektroluminiscenčních součástek řízených střídavým proudem (ACTFEL) a zejména vliv procesu stárnutí luminiforů na jejich optické a elektrické vlastnosti. Cílem této studie měl být příspěvek ke zvýšení celkové účinnosti luminoforů, vyjádřené pomocí jasu, účinnosti a stability. Vzhledem k tomu, že současnou dominantní technologií plochých obrazovek je LCD, musí se další alternativní technologie plošných displejů porovnávat s LCD. Výhodou ACTFEL displejů proti LCD je lepší rozlišení, větší teplotní rozsah činnosti, větší čtecí úhel, či možnost čtení při mnohem vyšší intenzitě pozadí. Na druhou stranu je jejich nevýhodou vyšší energetická náročnost, problém s odpovídající barevností tří základních barev a podstatně vyšší napětí nutné pro činnost displeje. K dosažení tohoto cíle jsme provedli optická, elektrická a optoelektrická měření ACTFEL struktur a ZnS:Mn luminoforů. Navíc jsme studovali vliv dotování vrstvy pomocí KCl na chování mikrostruktury a na elektroluminiscenční vlastnosti (zejména na jas a světelnou účinnost) ZnS:Mn luminoforů. Provedli jsme i některá, ne zcela obvyklá, měření ACTFEL součástek. Vypočítali jsme i rozptylový poměr nabitých barevných center a simulovali transportní charakteristiky v ACTFEL součástkách. Studovali jsme vliv stárnutí dvou typů ZnS:Mn luminoforů (s vrstvou napařenou či získanou pomocí epitaxe atomových vrstev) monitorováním závislostí svítivost-napětí (L-V), velikost vnitřního náboje - elektrické pole luminoforu (Q-Fp) a kapacitance-napětí (C-V) ve zvolených časových intervalech v průběhu stárnutí. Provedli jsme krátkodobá i dlouhodobá měření a pokusili jsme se i o vizualizaci struktury luminoforu se subvlnovým rozlišením pomocí optického rastrovacího mikroskopu pracujícího v blízkém poli (SNOM). Na praktickém případu zeleného Zn2GeO4:Mn (2% Mn) ACTFEL displeje, pracujícího při 50 Hz, jsme také studovali stabilitu svítivosti pomocí měření závislosti svítivosti na napětí (L-V) a světelné účinnosti na napětí (eta-V). Přitom byl zhodnocen význam těchto charakteristik. Nezanedbatelnou a neoddělitelnou součástí této práce je i její pedagogický aspekt. Předložený text by mohl být využit i jako učebnice pro studenty na mé univerzitě v Lybii.
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Mathe, Mahlanyane Kenneth. "Electrodeposition of nanostructures by electrochemical atomic layer epitaxy (EC-ALE)." 2003. http://purl.galileo.usg.edu/uga%5Fetd/mathe%5Fmahlanyane%5Fk%5F200312%5Fphd.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Georgia, 2003.Directed by John L. Stickney. Includes articles submitted to Chemistry of materials, Applied surface science, Journal of the Electrochemical Society, Journal of applied physics, and Journal of crystal growth. Includes bibliographical references.
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Muthuvel, Madhivanan. "Electrodeposition of compound semiconductors on indium phosphide (INP) using Electrochemical Atomic Layer Epitaxy (EC-ALE)." 2005. http://purl.galileo.usg.edu/uga%5Fetd/muthuvel%5Fmadhivanan%5F200512%5Fphd.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Georgia, 2005.Directed by John L. Stickney. Includes an article accepted by Journal of the Electrochemical Society, and articles submitted to Langmuir and Journal of the Electrochemical Society. Includes bibliographical references.
24
Vaidyanathan, Raman. "Electrodeposition of quantum confined thin films and nanostructures by electrochemical atomic layer epitaxy (EC-ALE)." 2003. http://purl.galileo.usg.edu/uga%5Fetd/vaidyanathan%5Framan%5F200308%5Fphd.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Georgia, 2003.Directed by John L. Stickney. Includes articles published in Electrochemical processing in ULSI fabrication III: Electrochemical Society proceedings, MRS symposium proceedings, and Journal of electroanalytical chemistry, and articles submitted to Electrochimica acta, Journal of crystal growth, and Journal of applied physics. Includes bibliographical references.
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Flowers, Billy Hugh. "The automation of electrochemical atomic layer epitaxy (EC-ALE) for the production of thin film semiconductors." 2001. http://purl.galileo.usg.edu/uga%5Fetd/flowers%5Fbilly%5Fh%5F200112%5Fphd.
Повний текст джерела
26
Varazo, Kristofoland. "The underpotential deposition and surface characterization of metal and chalcogenide atomic layers used in electrochemical atomic layer epitaxy (EC-ALE): cadmium, tellurium, and sulfur." 2001. http://purl.galileo.usg.edu/uga%5Fetd/varazo%5Fkristofoland%5F200112%5Fphd.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Georgia, 2001.Directed by John L. Stickney. Includes articles submitted to Journal of electroanalytical chemistry, Surface science, and Langmuir. Includes bibliographical references.
27
Cox, Stephen Matthew. "Quantum confinement effects on the energy gaps of PbSe semiconductor thin films created using electrochemical atomic layer epitaxy." 2003. http://purl.galileo.usg.edu/uga%5Fetd/cox%5Fstephen%5Fm%5F200308%5Fms.
Повний текст джерела
28
Lay, Marcus David. "Atomic level studies of electrochemical reactions used in electrochemical atomic layer epitaxy (EC-ALE): cadmium, lead, tellurium, cadmium telluride, mercury, mercury telluride, sulfur, sodium thiosulfate, and sodium ethane thiolate." 2003. http://purl.galileo.usg.edu/uga%5Fetd/lay%5Fmarcus%5Fd%5F200305%5Fphd.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Georgia, 2003.Directed by John L. Stickney. Includes an article published in Journal of the American Chemical Society, and articles submitted to Journal of electroanalytical chemistry, Eletrochimica acta, Journal of the American Chemical Society, and Langmuir. Includes bibliographical references.
29
Berretti, Enrico. "ELECTRODEPOSITION AND CHARACTERIZATION OF METALS FOR IMPROVED CORROSION RESISTANCE AND ENERGY CONVERSION." Doctoral thesis, 2018. http://hdl.handle.net/2158/1120081.
Повний текст джерелаАнотація:
Until today, research on the electrodeposition topic has developed a broad range of solutions for the obtainment of coatings of different elements, compounds, and alloys, but some issues related to the deposition of certain metals, and the electrochemical stability and safety of the relative plating baths are still unresolved. The present research work was focused on two main topics, both related to the development of electrodeposition processes, and the characterisation of the obtained coatings: a) Electrodeposition and characterisation of palladium films as catalyst (Anodic) layers in Direct Ethanol Fuel Cells (DEFCs). b) Electrodeposition and characterisation of aluminium metal films from Ionic Liquids (ILs);
Both the addressed topics have a high industrial relevance in the field of energy production, but they have needed two slightly different approaches to the study of the involved phenomenon.
The work on the electrodeposition from ionic liquids was, in fact, part of an European project (SCAIL-UP, HTTP:/scailup.eu) for the scaling up of the aluminising operation from ionic liquids, from a lab scale set-up to an industrial process. The final objective of this project was, in fact, the production of a pilot plant for the aluminization process via ionic liquids of turbine vanes for energy and aerospace applications. My work on this topic mainly focused on technological and industrial aspects of electrodeposition, in the research of the optimal deposition conditions to obtain metallic layers with specific properties (thicknesses, corrosion resistance and morphology).
On the other hand, the study and characterisation of Pd surfaces for alcohol reactions in alkaline Direct Ethanol Fuel Cells (DEFCs) had a more fundamental science footprint. This research focused mainly on the improvement of an analytical technique used in high fluence X-Ray sources (Synchrotrons), and on the development of electrodeposition methodologies for the preparation of ordered metallic layers usable as model catalytical coatings for the study of alcohol electrooxidation. Particular focus was paid on palladium, a promising metal for the anodic reactions in Alkaline Direct Alcohol Fuel Cells (DAFCs). Two main electrodeposition techniques were used to control the amount of deposited palladium: the Electro-Chemical Atomic Layer Deposition (E-ALD) and the Surface Limited Redox Replacement (SLRR). Part of this work was carried out during two experiments at the European Synchrotron Radiation Facility (ESRF) in Grenoble during the last year, performed by X-Ray Absorption Spectroscopy (XAS).
In the end, both the addressed research topics exploited state of the art deposition and characterization techniques to study the obtained metal coatings. The ability to precisely control deposit coverage and thicknesses via E-ALD and SLRR, the possibility to electrodeposit metals from “exotic” electrolytes like ionic liquids and the use of in situ synchrotron techniques to characterize the obtained metallic films could permit, in future, to design and prepare new materials and devices of great industrial interest, to overcome today’s manufacturing limitations.
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Hsieh, Shyang-Lin, and 謝祥麟. "Atomic Layer Epitaxy of AlGaN." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/48721060772478035277.
Повний текст джерелаАнотація:
碩士逢甲大學
材料科學學系
87
The purpose of this study is to explore the effect of the growth conditions and substrate orientations on the crystal structure, crystallinity and optical properties of the AlGaN films. AlGaN films were grown on (0001) and (11-20 ) sapphire substrates by atomic layer epitaxy at a temperature range of 950~1050℃. Group III metalorganics and NH3 were used as the sources of Al, Ga, and N atoms that were carried into the reactor by purified H2. The incorporation of Al in the AlGaN films increases linearly with the increment of TMA/(TMG+TMA) ratio in the gas phase. However, increment in Al content tends to result in the formation of microcracks when AlGaN film thickness is beyond its critical layer thickness. Increment in growth temperature is helpful in improving the material quality of AlGaN films. The PL intensity of the yellow emission is greatly reduced as growth temperature increases. In addition to the near bandedge emission and yellow luminescence, a blue emission near 3.0 eV was observed in the AlGaN films grown on the AlN-coated c-Al2O3 substrates. AlGaN/GaN double heterostructures and quantum wells were also successful grown on c-sapphire substrates at 1050℃.
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Liao, Wei-Tsai, and 廖偉材. "Atomic Layer Epitaxy of AlxGa1-xN/GaN Superlattices." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/jh269t.
Повний текст джерелаАнотація:
碩士逢甲大學
材料科學所
90
Abstract The purpose of this study is to explore the effects of the growth conditions on the crystal structure, crystallinity and optical properties of the AlxGa1-xN /GaN superlattices.The AlxGa1-xN /GaN superlattices were grown on（0001）sapphire substrates by atomic layer epitaxy. Groups III metalorganics and NH3 were used as the sources of Al, Ga, and N atoms that were carried into the reactor by purified H2. The surface morphology, crystallinity and optical properties of AlxGa1-xN /GaN superlattices were investigated by Nomarski interference optical microscope , x-ray diffractometry（XRD）, Auger electron spectroscopy（AES）, transmission electron microscopy（TEM）and absorption spectroscopy. The results indicate that the absorption edge of an AlxGa1-xN/GaN superlattice increases as the well thickness decreases. It appears that the cut-on energies of the absorption edges of AlN/GaN superlattices are larger than those of AlxGa1-xN/GaN（0＜x＜1）superlattices with the same sizes of well and barrier layer thicknesses .
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Luo, Choung-Ting, and 羅中廷. "Atomic Layer Epitaxy of NaCl on Ge Surface." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/86400964030726818393.
Повний текст джерелаАнотація:
碩士國立交通大學
物理研究所
96
This thesis describes the atomic layer epitaxy of NaCl on Ge(100) surface. The experimental method employed is the high-resolution X-ray photoemission spectroscopy using synchrotron radiation as the photon source. Photoelectron spectra from the Ge 3d, Na 2p and Cl 2p core levels and from the NaCl valence band have been analyzed for the growth NaCl crystals. We can observe the NaCl band-offset when growing Cl and Na atoms alternately. Chlorine termination of NaCl ultra-thin film can increase the charge density on the surface, leading to the NaCl band offset. The valence band offset ranges from 1.66 ~ 1.67 eV. Finally, when evaporating about 1.2ML of the Na atoms on the surface. The surface returns to charge neutrality, and the bands become flat again.
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Jung-Ting, Chang, and 張榮庭. "Study of Atomic-Layer-Epitaxy Controlled MOCVD GaAs Epi-layer on Ge Substrate." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/19240612958150924137.
Повний текст джерелаАнотація:
碩士國立交通大學
工學院半導體材料與製程設備學程
100
GaAs epitaxy, as nucleation layer, is grown on Ge substrate using ALE technique (Atomic Layer Epitaxy). According our study, triangle defects are formed on the surface of (In)GaAs/Ge due to lower decomposition rate of TMGa at low growth temperature (415°C). For ALE technique, the multilayer consisted of 10 pairs of Ga and As layers can improve epitaxial quality (15 arcsec) and surface morphology (1.22nm) of (In)GaAs/Ge heterostructure at 420°C. The growth temperature of 420°C is also adopted to suppress unwanted interdiffusion during (In)GaAs/Ge heterostructure growth. Moreover, long purge time (＞20sec) results arsenic desorption from the surface of ALE-GaAs epitaxy and affects epitaxial quality during InGaAs/GaAs/Ge heterostructure growth. It is demonstrated that GaAs nucleation layer grown on Ge substrate using ALE technique has great potential to replace InGaP layer of traditional III-V solar cell for suppressing unwanted interdiffusion and producing smooth surface morphology.
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Lee, Nien-chung, and 李年中. "The Study of ZnS Thin Films by Atomic Layer Epitaxy." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/97810032775445755086.
Повний текст джерелаАнотація:
碩士國立成功大學
電機工程研究所
83
Atomic Layer Epitaxy is a stepwise deposition process by su- pplying the sources materials alternatively.This deposition te- chnique provides monolayer control of the deposited film thick- ness and uniform growth over a large area． ZnS layers were grown epitaxially onto (100)GaAs,(100)Si, (222)ITO substrates under low pressure in a horizontal vaper phase epitaxial reactor using DMZn for the group II source and H2S gas for the group VI source.In this study, We varied the growth condition, including change of the substrate temperature, the mole fraction of DMZn,the mole fraction of H2S,the purge H2 duration, the pressure of reaction chamber ...etc.In order to privide high quality ZnS epitaxial films. In ZnS grown on GaAs,the present process provides the mono- layer growth over a wide range of growth condition in a self- limiting manner.High crystalline quality of the epitaxially grown layers can be obtained by XRD,SEM,EPMA and PL,in spite of very large lattice mismatch (4.4 %) between ZnS and GaAs. In ZnS grown on Si and ITO glasses,The ZnS films have high crystalline quality and the epitaxial layers had a mirror-like surface.But the growth rate was still at 0.7 monolayer over a wise range of growth condition.It may be possible because the adsorption of the reactions on the substrates is weak; and much higher flows or flow times may be needed for monolayer
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Wang, Hong-Yi, and 王宏益. "Thermodynamic Analysis on ZnSxSe1-x Grown by Atomic Layer Epitaxy." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/21346879583566000963.
Повний текст джерелаАнотація:
碩士國立中山大學
電機工程學系研究所
91
Atomic Layer Epitaxy is a stepwise deposition process by supplying the sources materials alternatively. This deposition technique provides the monolayer control of film thickness and the uniform film growth over a large area. ZnSxSe1-x layers were grown epitaxially onto Si and GaAs substrate by using DMZn and H2S , H2Se gases for the reactant source. Owing to the self-limiting characteristics of ALE process, ZnSxSe1-x monolayers could be deposited over a wide range of temperature within growth window. In this study, for obtaining high crystalline quality ZnSxSe1-x epitaxial films, various growth conditions were investigated including substrate temperature, the flow rate of DMZn, H2S and H2Se, H2 purge duration and pulse duration etc.. A thermodynamic analysis based the calculation of Seki et. al [6], was used to investigate the effects by varying the substrate temperature, input mole ratio of group VI source gases on equilibrium partial pressure, solid composition and solid-vapor distribution relation of this alloy. The interaction parameter of ZnSxSe1-x, Ω, was estimated by using the delta-lattice parameter (DLP) model suggested by Stringfellow [39]. Finally, it shows that the thermodynamic analysis provides a useful guideline for the growth of ZnSxSe1-x alloy on Si and GaAs substrates.
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Hsu, Ming-Yuan, and 許名沅. "Electrochemical Atomic Layer Deposition of Cu-Ru Film." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/9av6wk.
Повний текст джерелаАнотація:
碩士國立虎尾科技大學
材料科學與綠色能源工程研究所
102
Preparation of the atomic layer films by an electrochemical atomic layer deposition (ECALD) can solve step coverage issues. This technique can also be used to prepare copper alloy films for semiconductor process. This study presents copper (Cu) films doped with ruthenium (Ru), and hopes the film have a better stability because Ru has good thermal stability and low resistivity. However, preparation of Cu-Ru films by ECALD is rarely studied. This experiment is to analyze and discuss the Cu-Ru alloy films prepared by ECALD. Cu-Ru films were deposited on Au/Ti/glass substrates by ECALD. The process using surface limited redox replacement (SLRR) and underpotential deposition (UPD) to prepare the films. Pb UPD was formed at -0.54 V versus Ag/AgCl, and in Cu solution at open circuit for 1 minute performing redox replacement of Pb UPD by Cu. After that, Ru was deposited in solution at -0.6 V versus Ag/AgCl for 1 minute. The films were deposited by repeating the above processes. After deposition, the samples were annealed at 400℃ in Ar + H2 (95%+5%) atmosphere for 5 minutes. The sheet resistance of the film was measured by four-point probes, film thickness was measured by Alpha-step, crystal structure was analyzed by XRD, surface morphology and cross-sectional images were observed by FE-SEM, atomic concentration was measured by EDS, and atomic binding energy and quantitative analysis were measured by XPS. The results showed that optimal parameters can be obtained at UPD of Cu sol. : -0.1 V, Pb sol.: -0.54 V, and Ru sol. : -0.6 V from the pH 3.5 solution. Cu deposition gradually decreased when increasing Ru deposition because deposition rate of the Pb was slowed down on the Ru film. Au-Cu alloy was formed after annealing at 400℃ for 5 minutes, which resulted in an increase in resistance and densification of the film.
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Wang, Chen-Yu, and 王晨宇. "New Ga-source precursor developed for atomic layer epitaxy of GaN." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/30581781313910392608.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
化學工程系
93
The aim of this study is placed on : (1) investigating the film-growth mechanism of gallium nitride (GaN) by atomic layer epitaxy (ALE) technique using TMG/NH3 reaction system, (2) investigating the film-growth mechanism of indium nitride by atomic layer epitaxy (ALE) technique using TMIn/NH3 reaction system, (3) exploring the indium content in InGaN films by using different feed rule of Ⅲ-precursor. In the first part, atomic layer epitaxy of GaN films are investigated using trimethylgallium (TMG) and ammonia (NH3) as the reactant gases. It is found that carbon contamination and polycrystalline of one monolayer/cycle growth was obtained at a temperature ranging from 480 to 550℃. On the other hand, carbon-free and single crystal can be found when the growth is preformed at 675℃, but the surface roughness is serious. In the second part, atomic layer epitaxy of InN films are investigated using trimethylindium (TMIn) and ammonia (NH3) as the reactant gases. The result shows that Indium metal precipitate on the surface when the NH3 exposure time is not enough and film-growth at low temperature. In the third part, atomic layer epitaxy of InGaN films are investigated with different feed rule of Ⅲ-precursor and the effect of In-content in each films at 535℃. At mixing feed of Ⅲ-precursor, In-content is closed to 7.5% and Indium metal precipitate on the surface due to insufficient cracking of NH3 at low temperature. At TMG prior feed rule, the In-content increases to 55.5% with decreasing TMG exposure time to 1s. Unfortunately, Indium metal precipitate in each films. At TMIn prior feed rule, high In-content (74%) of InGaN can be achieved, but the phase separation occurs simultaneously.
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Ciou, Wei-Jhen, and 邱唯禎. "Isomorphic Epitaxy of Wurtzite ZnO/AlO Superlattices by Atomic Layer Deposition." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/z4rddh.
Повний текст джерелаАнотація:
碩士國立中山大學
物理學系研究所
107
The thesis aims at growth of m-oriented ZnO/AlO superlattices on m-sapphire substrates. Samples were prepared by ALD at 450K. The precursors pulse times were iterated to fined-tune the growth conditions according to the resulted sample qualities as judged by their thickness, surface or interface roughness, and epitaxy characterized by various techniques of X-ray diffraction (XRD), including the -2 scans, -scans, X-ray reflectivity (XRR), and grazing incidence X-ray diffraction (GIXRD) to quantify the orientation and the general quality of epitaxy. The epitaxial relationships between the ZnO films and the substrate were determined to be ZnO[11"2" ̅0] // Al2O3[0001], but the expected relation of m-oriented films on m-oriented sapphire substrate, namely, ZnO(10"1" ̅0) // Al2O3(10"1" ̅0) was found to be off by a small angle, with an interface with ZnO(10"1" ̅0) ∧ Al2O3(10"1" ̅0) 1.79° tilted by rotation around the c-axis of the substrate. Preliminary attempts at high-resolution TEM imaging of a sample prepared by focused ion beam cutting were unsuccessful as no clear interfacial boundaries were observed. To improve the growth, an epitaxial ZnO buffer layer was first deposited at 923K by sputtering on the substrate before the ALD growth, by which characteristic oscillatory patterns were successfully seen in the XRR spectra. The unevenness in the thickness, mass density and roughness of each layer are believed to be responsible for the absence of peaks characteristic of the periodicity of a superlattice in the XRR patterns, despite the overall success of the epitaxial growth in the desired m-orientation as verify by XRD and GIXRD.
39
Chen, Ying-Zhang, and 陳盈璋. "The electrical and optical properties of ZnS/ZnSe strained-layer superlattice by Atomic Layer Epitaxy." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/01947596128001604228.
Повний текст джерелаАнотація:
碩士國立成功大學
電機工程學系
87
In this dissertation, we will discuss the effects and roles of ZnS/ZnSe strained-layer superlattices (SLSs) for introducing it into the Electroluminescent devices. The SLSs layer is grown on n-type silicon by Atomic Layer Epitaxy (ALE) which modified in a low pressure, horizontal-type, MOCVD system using dimethylzinc, hydrogen sulphide and hydrogen selenide as the reactants. The formation of SLSs structure is evident from the altering behavior of each fluctuation profile by SIMS. The electrical property of SLSs schottky diode is investigated by current-voltage measurement. It is found that at least 16 periods of ZnS/ZnSe (1600 A) will represent as low cut-in voltage as 0.52V. ZnS:Tm phosphor layer is deposited on SLSs/Si and discuss the role of SLSs as a buffer layer. Under photoluminescence spectra performed at room temperature, an unnecessary peak around 4000A is suppressed while compare it with one which have a ZnSe buffer layer with comparable thickness. All this point out the appropriateness of SLSs as an electron-transmission layer and buffer layer in Electroluminescent devices.
40
Lin, Chi-Hung, and 林繼宏. "Atomic layer epitaxy of gallium nitride using diethylgallium chloride as gallium source." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/uvcdgs.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
化學工程系
94
allium nitride (GaN) and Indium gallium nitride (InxGa1-xN) films were grown by metalorganic atomic layer epitaxy (ALE) technique using diethylgallium chloride (DEGaCl) as source material for Ga in a cold-wall, chemical vapor deposition reactor. Self-limiting growth were obtained over a wide range of growth conditions, including growth temperatures (773~873 K) and the exposure time of DEGaCl. When the substrate temperature was 773 K, the films formed showed polycrystalline property. Increasing substrate temperatures to 823 ~873 K, epitaxy GaN (0002) films were obtained. The most advantage of DEGaCl was in its capability to form extremely uniform GaN films. Another try to form tertiary InxGa1-xN layers by further adding trimethylindium (TMI) was also made. The results showed that the In content in the films could be increased up to 20% (InxGa1-xN, x<0.2), when the feed ratio of [TMI]/[DEGaCl] was set at 2 under 853 K. However, In metal precipitation was accompanied, probably due to the deficiency of N supply because of the inertness of NH3 under this low temperature. The less adsorption of metal In compared with the adsorbed GaCl maybe another reason for the low In incorporation amount.
41
Liu, Chun-Hsing, and 劉醇星. "Electrical and Photo Properties of ZnS/ZnSe Strained Layer Superlattice Films by Atomic Layer Epitaxy ethod." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/11275994204454241051.
Повний текст джерелаАнотація:
博士國立成功大學
電機工程學系研究所
86
In this thesis, we havwe successfuully grown apparently high quailty un doped ZnSe, ZnS, ZnS/ZnSe strained layer sperlattice films on (100)-Si substrates by ALE in modidied, low pressure, horizontal-type , MOCVD system. ALE is an suit able technique for the growth of the ultra thin semiconductors because it prov ides accuracy monolayer control of the deposited fiilm thickness, low growth t emperature by its self-limiting mechanism.From X-ray diffraction pattern, (400 )-oriented single-crystal epilayers of ZnSand ZnSe are evidenced. From PL spec tra, we observe the emission at 337 nm thought to be due to band-to-bamd trans ition at 300K in ALE-ZnS on Si substrate for the first time. 7K PL spectra ofZ nSe epilayer is dominated by the strong near band edge at 2.81eV with FWHM of 36 meV. The hall mobility and carrier concentration of the undoped ZnSe are 55 0cm^2/v-sec and in order of 10^15 cm^-3 at room temperature. The Au/ZnSe Schot tky diode has a low leakage current, i.e. 4.5nA at 15V reverse voltage for a 0.1 cm-diameter Schottkky contact and a high breakdown voltage over 40V.For th e ZnS/ZnSe, the emission peak shifted towards to high energy side with decreas ing ZnSe well-layer thickness, a "blue-shift" is evidenced. From our results, a slightly Stoke shift, 16 meV and linewidth 13.8-38meV from 7K to 148K by PL measurements, it is more less than other growth techniques. The theoretical re sults are discussed using the Kroning-Penny model and takking into account str ain effects in the valence band of the SLSs. It is found that the quantum size effects are ascertained through the photon energy with the ZnSe well layer th ickness. The I-V characteristics of the SLSs have quite low cut-in voltages of 80-150 meV. The low cut-in voltage seems to arises from the advanced SLSs str ucture, in which an electron''s mean free path is much shorter than in single c rystal ZnSe and faster electron transmission by the quantum effects.
42
Thambidurai, Chandru. "Electrodeposition of thin films by electrochemical - atomic layer deposition (ALD)." 2009. http://purl.galileo.usg.edu/uga%5Fetd/thambidurai%5Fchandru%5F200912%5Fphd.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of Georgia, 2009.Directed by John Stickney. Includes articles published in Electrochimica acta and Journal of the Electrochemical Society. Includes bibliographical references.
43
Tzou, Dong-Ying, and 鄒東穎. "Synthesis of Pt Nanoparticles by Atomic Layer Deposition for Electrochemical Catalysis." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/76564166176875493445.
Повний текст джерелаАнотація:
博士元智大學
化學工程與材料科學學系
105
Part I This study adopts a modified atomic layer deposition (ALD) process to prepare size-controlled Platinum (Pt) nanoparticles over the surface of carbon black, showing superior catalytic activity toward ethanol oxidation. Two types of ALD precursors, (methylcyclopentadienyl) trimethyl platinum (MeCpPtMe3) and oxygen (O2), were used to grow Pt deposits at 250°C. For 30 ALD cycles, the pulse period of MeCpPtMe3 serves as a key factor in controlling the particle size and the weight loading of Pt deposits. The Pt growth rates over the carbon support can be attributed to the surface coverage of Pt-O* sites, diffusion rate of MeCpPtMe3, and lateral interaction between each active site. Since the MeCpPtMe3 dose strongly affects the Pt particle size and the deposit density, the growth of ALD-Pt can be taken into account as diffusion-limiting. Due to its surface-catalyzed reaction steps, the small-sized ALD-Pt catalysts offer better catalytic activity, CO tolerance, and long-term stability as compared with the large-sized ones. On the basis of the results, the modified ALD technique exhibits a great potential for tuning the Pt particle size and weight loading onto the carbon support for fuel cell application. Part II The present work adopts an ALD technique to synthesize highly-crystalline Pt nanoparticles onto carbon powders, offering superior catalytic activity toward methanol oxidation within the temperature range of 25-55°C. Uniformly-dispersed Pt nanoparticles with an ultralow loading are coated over the carbon supports, served as catalyst materials for methanol electro-oxidation. Experimental results reveal that ALD-Pt catalyst offers not only an improved catalytic activity toward methanol oxidation but also superior CO tolerance, as compared to commercial Pt one. The decreased current ratio for direct to indirect pathway with an increase in temperature is found, referring to the kinetic limitations for the formation and oxidation of Pt-(CO)ads sites at high temperatures. Followed up Arrhenius-type behavior, small apparent activation energies (i.e., ca. 30.3 and 41.7 kJ mol-1) of ALD-Pt catalyst can be achieved for dehydrogenation of methanol (direct pathway) and oxidation of adsorbed CO species (indirect pathway) in methanol oxidation reaction. The low potential barrier on ALD-Pt catalyst is attributed to small particle size (i.e., average particle size of 2.1 nm) and oxidized Pt surface (i.e., native Pt-O* active sites) that efficiently enhance the catalytic activity and CO tolerance, respectively. As a result, this study examines the influence of temperature on catalytic activity and anti-poisoning performance on the ALD-Pt catalyst, in which the surface chemistry and structural motif is more efficient at electrochemically oxidizing methanol and improving the CO tolerance.
44
Tang, Chak-wah, and 鄧澤華. "The Study of ZnSe-ZnS Strained-Layer Superlattices & Electrical Characteristics of ZnSe Epilayer by Atomic Layer Epitaxy." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/61858330790910008277.
Повний текст джерелаАнотація:
碩士國立成功大學
電機工程研究所
84
In this dessertation, high quality epitaxial growth of undoped ZnSe, ZnS, ZnS-ZnSe single quantum well and their strained- layer superlattices have been successfully grown on (100)- oriental silicon substrates by Atomic Layer Epitaxy (ALE) which modified in a low pressure, horizontal-type, MOCVD system using dimethylzinc, hydrogen sulphide and hydrogen selenide as the reactants for the first time. The growth temperature of ZnS/ ZnSe superlattices as 150℃ would be lowered to eliminate 3-D growth due to the highly lattice mismatch between ZnS and ZnSe. The formation of the SLS structure is evident from the periodic behavior of each fluatuation profile by SIMS. 45 periods of ZnS(51A)-ZnSe(15A), have shown a slightly Stoke shift 16 meV with the peak energy 3.097 eV and the linewidth is 13.39 meV at 7K. At least 25 periodic thickness of the ALE growth samples show a strong blue emissions and nearly neglects the deep level emission at room temperature. The highest Hall mobility and carrier concentration of the undoped ZnSe are 550cm2/v-sec and in order of 10-15 cm-3 at room temperature. The undoped ZnSe Schottky diode has an excellent electrical properties at room temperature such as low eakage current, 4.5 nA at 15 V reverse voltage, high breakdown voltage over 40 V, ideality factor in the range of 1.10~7.63 and with low cut-in voltages of 0.6~0.97 V. The effect of annealing temperature on electrical properties have also been studied. The improvement of I-V characteristics by the SLS structure with quite low cut-in voltages of 80~150 meV.
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Lin, Po-Hung, and 林柏宏. "Investigations of the AlGaN films and AlN/AlGaN superlattices grown by Atomic Layer Epitaxy." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/gc6eb9.
Повний текст джерелаАнотація:
碩士逢甲大學
材料科學所
90
Abstract The purpose of this study is to explore the effects of the growth conditions on the crystal structure, crystallinity and optical properties of the high Al content AlxGa1-xN films and AlN/AlxGa1-xN superlattices. The samples were grown on (0001) sapphire substrates by atomic layer epitaxy. Groups III metalorganics and NH3 were used as the sources of Al, Ga, and N atoms that were carried into the reactor by purified H2. The crystallinity and optical properties of AlxGa1-xN films and AlN/ AlxGa1-xN superlattices(SLs) were investigated by transmission electron microscopy (TEM), x-ray diffractometry(XRD), absorption spectroscopy, and Auger electron spectroscopy(AES). The 0.4 μm thick AlxGa1-xN films exhibited a two-step absorption cut-on edges at 3.5eV and 4.1eV, respectively. This composition separation phenomenon was also revealed by X-ray diffraction measurement, Auger electron spectroscopy and cross-sectional TEM observations. The results of absorption measurement for a set of AlN/ AlxGa1-xN (x~0.5) superlattice structures with various well width of 30 to 65Å and a barrier thickness of 40 Å were reported. The absorption edges of these SLs were observed to decrease monotonously with increment of well width up to 65Å. This result is attributed to the quantum size effect.
46
Hung, Jia-Hong, and 黃家宏. "Preparation of Ag andAg(Cu) Thin Film by Electrochemical Atomic Layer Deposition." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/f64s7d.
Повний текст джерелаАнотація:
碩士國立虎尾科技大學
材料科學與工程系材料科學與綠色能源工程碩士班
104
Due to the increase in the edvice density recentry, lead to increase in RC delay. when the device size is down. Silver has shown a reduced electrical resistance but suffer from stability and adhesion. In this report, we used Electrochemical Atomic Layer Deposition (EC-ALD) technology to prepare the Ag and Ag(Cu) films. The Si (100) wafer was coated with 10 nm Ru by sputter, and that was cleamed by cyclic voltammetry (CV) at a scan rate of 5 mV/s. The first Underpotential deposition (UPD) Cu-layer was deposited on the Ru substrate. Pb was choosed as a sacrificial layer on the Cu/Ru/Si substrate and then Cu sol. and Ag sol was flushed into cell at OCP 60s that Pb was exchanged Ag and Cu atom by Surface limited redox replacement (SLRR) . Another mix solution of (Ag + Cu) was flushed into cell at OCP for 60 s that Pb was exchanged for Ag & Cu atom by SLRR. Ag-Cu film was formed by repeated process for 48 cycles. The resulting Ag(Cu) films were characterized using X-ray diffraction, electrochemical chromatograpHy and four point probe, Scanning electron microscope and X-ray Photoelectron Spectrometer.
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McDaniel, Martin Douglas. "Monolithic integration of crystalline oxides on silicon and germanium using atomic layer deposition." Thesis, 2015. http://hdl.handle.net/2152/30474.
Повний текст джерелаАнотація:
Inside your microelectronic devices there are up to a billion transistors working in flawless operation. Silicon has been the workhorse semiconductor used for the transistor; however, there must be a transition to materials other than silicon, such as germanium, with future device sizes. In addition, new dielectric oxide materials are needed. My research has examined a type of crystalline oxide, known as a perovskite, which is selected for its ability to bond chemically to Si and Ge, and eliminate the electrical defects that affect performance. Many perovskite oxides are lattice-matched to the Si (001) and Ge (001) surface spacing, enabling heteroepitaxy. To date, the majority of research on crystalline oxides integrated with semiconductors has been based on strontium titanate, SrTiO3, epitaxially grown on Si (001) by molecular beam epitaxy. Alternative low-temperature growth methods, such as atomic layer deposition (ALD), offer both practical and economic benefits for the integration of crystalline oxides on semiconductors.
My initial research informed the broader community that four unit cells (~1.5 nm) of SrTiO3 are required to enable heteroepitaxy on Si. The research has also shown that heteroepitaxial layers can be monolithically integrated with Si (001) without the formation of a SiOx interlayer between the Si (001) surface and the SrTiO3 layer because ALD is performed at lower temperatures than are typical for MBE. Thus, a combined MBE-ALD growth technique creates possible advantages in device designs that require the crystalline oxide to be in contact with the Si (001) surface.
In recent work, I have demonstrated a method for integrating crystalline oxides directly on Ge by ALD. Germanium is being explored as an alternative channel material due to its higher hole and electron mobilities than Si, potentially enabling device operation at higher speed. This all-chemical growth process is expected to be scalable, is inherently less costly from a manufacturing cost of ownership, and is based on current manufacturing tool infrastructure. The impact of my research will be in continued scaling of device dimensions with novel materials that will provide faster speed and lower power consumption for microelectronic devices.text
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Leu, Chia-Jen, and 呂嘉仁. "Electrical and Optical Properties of ZnSSe Thin Films Grown on Si by Atomic Layer Epitaxy." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/61818064230802360990.
Повний текст джерелаАнотація:
碩士國立成功大學
電機工程學系
85
Atomic layer epitaxy (ALE) growth and characterization of ZnSSe on n-type (100) Si substrates are investigated for the first time by a low pressure horizontal MOCVD system using DMZn, H2S and H2Se as the reactants. Energy Dispersive Spectrometer attacehd on Scanning Electron Microscopy (SEMEDS), X-ray Diffraction (SIMS) ere used to determine the elemental composition and depth profile. Electrical and optical properties of the ZnSSe epilayers are characterized by current-voltage (I-V) measurements, Hall measurements and photoluminescence (PL). Undoped ZnSSe epilayers were grown at the growth temperature of 175℃ and pressure of 30 torr. The vapor-solid distribution relationship for the group VI elements is experimentally obtained. The layer lattice-matched to the Si substrate at a sulfur content about 93％ shows a better surface morphology and a narrower FWHM of XRD. From PL spectra, the ZnSSe energy gaps were deduced and a stronger near band edge was exhibited at the epilayer of ZnS0.93 Se0.07. The highest Hall mobility of the undoped ZnS0.93 Se0.07 is 347 cm2/v-sec. The Schottky diode has an excellent electrical properties at room temperature such as low leakage current, 45 nA at 20 V reverse voltage, high breakdown voltage over 40 V, and with low cut-in voltages of 0.68V. These results suggest that the Si substrates may be available for growing sufficiently high-quality by ALE.
49
Chen, Shuo-Wei, and 陳碩偉. "Synthesis of Gallium Nitride and Indium Gallium Nitride Films by Atomic Layer Epitaxy (ALE) Technique." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/39401353268067030541.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
化學工程系
92
Gallium nitride (GaN) layers have been epitaxially grown on GaN(002) substrate by the atomic layer epitaxy (ALE) method using trimethyl gallium (TMG) and ammonia (NH3) as the reactant gases. Polycrystalline growth is observed at low process temperature, and it turns into single-crystalline until high growth temperature. Additionally, indium gallium nitride (InGaN) layers have also been successfully synthesized by the ALE method using trimethyl indium (TMIn), TMG, and NH3 as reactants. The result shows that In content of InGaN film is as low as 11%. The adsorbability of TMIn to the GaN(002) substrate surface is less than TMG might explain this phenomenon.
50
Chen, Nyen-Ts, and 陳念慈. "Growth and Characterization of ZnSe, ZnSxSe1-x Heterostructures on Si Substrates by Atomic Layer Epitaxy." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/86804519666497902258.
Повний текст джерелаАнотація:
博士國立中山大學
電機工程學系研究所
88
Abstract High quality epitaxial growth of undoped ZnSe, ZnSxSe1-x and ZnSe-ZnS strained quantum well structures were successfully grown on n-type (100)-oriented silicon substrates at 150 ºC in a horizontal cold-wall quartz reactor by low-pressure metalorganic atomic layer epitaxy (MOALE) at a pressure of 30 Torr for the first time. Dimethylzinc [Zn(CH3)2, DMZn], hydrogen selenide (H2Se) and hydrogen sulfur (H2S) were used as the reactants. ALE is a suitable technique for the growth of ultra thin semiconductors because it provides accuracy monolayer control of the deposited film thickness, low growth temperature and uniform growth over a large area by its“ self-limiting mechanism ”via supplying source materials in a flow pulse sequences alternatively over the substrate. Idea one monolayer per cycle was obtained in wide range of parameters such as substrate temperatures, mole flow rate and pulse duration of reactants. From X-ray diffraction pattern, (400)-oriental single crystal epilayers of ZnSe are evidenced. The surface morphologies of ZnSe in the ALE temperature region 150 - 200 ℃, extensively smooth and mirror-like surface were obtained. PL spectra of ZnSe epilayer is dominated by the strong near-band-edge at 2.8 eV with FWHM of 36 meV. Schottky diodes were fabricated from the undoped ZnSe layer and the electrical properties were measured at room temperature. From the current-voltage (I-V) characteristics, a high reverse breakdown voltage (>40 V) and an excellent low cut-in voltage of 0.6 - 0.8 V were obtained. On the basis of the observed ZnSe/Si epitaxial film properties, the material is suitable for fabrication of ZnSe-based blue light emitting diodes and for application in direct-current thin-film electroluminescence. The lattice of the ZnSxSe1-x layer with a sulfur content around 93% was found to have the best match to the Si substrate, as confirmed by the good layer thickness, uniformity, surface morphology and narrow linewidth of the X-ray diffraction rocking curve with a minimal FWHM of about 0.16 degree. In addition, strong near-band-edge and weak deep-level emissions in the longer wavelength region dominate PL spectra of the ZnS0.93Se0.07 epilayer at 300K. With respect to Schottky diodes, Au/n-ZnS0.93Se0.07/Al, has a high breakdown voltage, over 40 V at 400 nA and a low cut-in voltage of 0.68 V. The highest Hall mobility of the ZnS0.93Se0.07 is 347 cm2/v-sec. These results indicate a good lattice-match of ZnS0.93Se0.07/Si as a result of low numbers of interface and epitaxial layer defects. The lower temperature of ZnSe-ZnS strained quantum well structures, 150 ºC would be lowed enough to eliminate 3-D growth related to the lattice mismatch between ZnSe and ZnS. A good epitaxy and crystallinity was carried out by X-ray diffraction. The formation of the strained quantum well structure is evident from the periodic behavior of each fluctuation profile by SIMS. At least 25 periodic thickness of the ALE growth samples shows a strong blue emissions and nearly neglects the deep-level emission at room temperature. The phenomenon of quantum size effects and the “ blue-shift ” was evidenced as the well width increases. The results of the PL measurements were found to correlate well with the theoretical one, parabolic well-strain mode. Schottky diodes were fabricated from the Au/ZnSe-ZnS SMQW/n-Si/Al, a high reverse breakdown voltage over 40 (at 20 µA) and an extremely low cut-in voltage of 80 - 120 mV were obtained. The I-V characteristics of the heterojunction are more suitable for the fabrication of the direct-current thin film electroluminescent (EL) device.