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The main aim of the diploma thesis is to investigate the influence of incorporated polyelecrolyte additives on the mechanical and transport properties of hydrogel. Hydrogels, based on polyvinylalcohol, were selected for these experiments. Gelation of polyvinylalcohol can be induced physically or chemically. The aim was to investigate the influence of sodium alginate, sodium polystyrene sulfonate and sodium polyglutamate. Mechanical properties were studied by rheology, through viscoelastic properties. Transport properties were analyzed by using two methods: diffusion pair and fluorescence correlation spectroscopy.

The present study aims to increase understanding of the physical processes that govern thermoelectric efficiency in Na-containing group 14 type II clathrates. This has been achieved through structural characterization and physical property measurements. Local and electronic structures of Si clathrates with the formula NaxSi136, where x = 0, 1.3, 5.5, 7.2, 8.8, 14.1, 20 and 21.5 were studied using x-ray absorption spectroscopy. Thermoelectric properties, namely Seebeck coefficient, electrical conductivity and thermal conductivity were measured from 2.5 K to 400 K. Low Na content samples, x < 8, showed reduced thermal conductivity compared to the empty clathrate, x = 0. For x > 8, increased Na content led to increased charge transfer, increased thermal conductivity and decreased magnitude of Seebeck voltages. The heat capacities of the NaxSi136 materials were measured from 2.5 K to 300 K. Analysis of the heat capacity data showed that the vibrational modes associated with Na in the Si28 cages are of sufficiently low energies to interact with heat transporting acoustic phonons, leading to reduced thermal conductivity as x is increased up to ~ 8. Increasing Na content beyond x = 8 introduces Na into the Si20 cages. This stiffens the lattice, increasing (or maintaining) phononic contributions to thermal conductivity, and increasing electronic contributions. Electronic thermal conductivity is responsible for upwards of 50 % of heat conduction when x = 21.5. Na containing type II Ge clathrates were produced using an ionic liquid reaction medium. Seebeck coefficients observed in Na9Ge136 materials, were negative but larger in magnitude than those of the NaxSi136 materials and thermal conductivities of Na9Ge136 were lower than those of the NaxSi136 materials. While both Si and Ge type II clathrates showed modest figures of merit, with maximum ZT values of 2.5 × 10-6 and 2.8 × 10-5 observed in Na20Si136 and Na¬9Ge136, of the two framework elements, type II Ge clathrates have been shown to have more favourable thermoelectric properties.

by Tsai Yau Moon = 錳氧化物的金屬-絶緣體轉變 : 多層薄膜及異構結 / 蔡友滿. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Tsai Yau Moon = Meng yang hua wu de jin shu-jue yuan ti zhuan bian : duo ceng bo mo ji yi gou jie / Cai Youman. / Abstract / 論文摘要 / Acknowledgements / Table of Contents / List of Figures / List of Tables / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Perovskite-type structure / Chapter 1.2 --- Metal-insulator transition / Chapter 1.3 --- Magnetoresistance / Chapter 1.3.1 --- Giant magnetoresistance (GMR) / Chapter 1.3.2.1 --- Colossal magnetoresistance (CMR) in perovskite manganites / Chapter 1.3.2.2 --- Possible origin of CMR / Chapter 1.4 --- Brief review of p-n junction between perovskite manganites and STON (001) / Chapter 1.5 --- Our project / Chapter 1.6 --- Scope of this thesis work / References / Chapter Chapter 2 --- Preparation and characterization of manganite thin films / Chapter 2.1 --- Thin film deposition / Chapter 2.1.1 --- Facing-target sputtering (FTS) / Chapter 2.1.2 --- Vacuum system / Chapter 2.1.3 --- Deposition procedure / Chapter 2.1.4 --- Deposition conditions / Chapter 2.1.5 --- Oxygen annealing system / Chapter 2.1.6 --- Silver electrode coating system / Chapter 2.2 --- Characterization / Chapter 2.2.1 --- Alpha step profilometer / Chapter 2.2.2 --- X-ray diffraction (XRD) / Chapter 2.2.3 --- Transport property measurement / References / Chapter Chapter 3 --- [LCSMO/PCMO] multilayers / Chapter 3.1 --- [LCSMO (100 A)/PCMO (X A)] multilayers / Chapter 3.1.1 --- Sample preparation / Chapter 3.1.2 --- Results and discussion / Chapter 3.1.2.1 --- Structural analysis / Chapter 3.1.2.2 --- Transport properties / Chapter 3.2 --- [LCSMO (50 A)/PCMO (X A)] multilayers / Chapter 3.2.1 --- Sample preparation / Chapter 3.2.2 --- Results and discussion / Chapter 3.2.2.1 --- Structural analysis / Chapter 3.2.2.2 --- Transport properties / References / Chapter Chapter 4 --- [LSMO/PCMO] multilayers and LSMO/STON p-n junction / Chapter 4.1 --- [LSMO/PCMO] multilayers / Chapter 4.1.1 --- Sample preparation / Chapter 4.1.2 --- Results and discussion / Chapter 4.1.2.1 --- Structural analysis / Chapter 4.1.2.2 --- Magnetization / Chapter 4.2 --- LSMO/STON heterojunction / Chapter 4.2.1 --- Sample preparation / Chapter 4.2.2 --- Results and discussion / Chapter 4.2.2.1 --- Structural analysis / Chapter 4.2.2.2 --- Metal insulator transition of LSMO revealed by four point I-V measurement / Chapter 4.3 --- Conclusion / References / Chapter 5 Conclusion / Chapter 5.1 --- Conclusion / Chapter 5.2 --- Future outlook

Land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers. Although nutrient rich, biosolids have been found to contain high concentrations of emerging contaminants (e.g. pharmaceuticals, personal care products) while containing a significant fraction of inorganic nano-scale colloidal materials such as oxides of iron, titanium, and aluminum. Given their reactivity and small size, there are many questions concerning the potential migration of these nano-sized colloidal materials through the soil column and into our surface and groundwater bodies. Transport of emerging pollutants of concern through the soil column, at minimum, is impacted by colloidal properties (e.g. chemical composition, shape, aggregation kinetics), solution chemistry (e.g. pH, ionic strength, natural organic matter), and water flow velocity. The purpose of this current research was to characterize the long-term transport behavior of aluminum oxide nanoparticles (Al2O3) through a natural porous media with changes in pH, aqueous-phase concentration, pore-water velocity and electrolyte valence. Additionally, deposition rates during the initial stages of deposition were compared to several models developed based on colloid filtration theory and DLVO stability theory. Benchtop column laboratory experiments showed that, under environmentally relevant groundwater conditions, Al2O3 nanoparticles are mobile through saturated porous media. Mobility increased under conditions in which the nanoparticles and porous media were of like charge (pH 9). Changes in linear pore water velocity, under these same high pH conditions, showed similar transport behavior with little mass retained in the system. Deposition is believed to be kinetically controlled at pH 9, as evidenced by the slightly earlier breakthrough as flow rate increased and was further supported by observed concentration effects on the arrival wave following several stop flows. While lower aqueous-phase concentrations resulted in significantly longer breakthrough times, the total mass retained in the system was found to be independent of concentration. Additionally, experimental deposition rate coefficients (kd), used to describe deposition kinetics under "clean bed" conditions, were similar across the aqueous-phase concentrations studied. The use of calcium chloride electrolyte solution in transport studies resulted in enhanced mobility relative to potassium chloride suggesting that changes in groundwater solution chemistry could impact mobility of contaminants associated with biosolids. Predicted deposition rate coefficients, using three different models, were found to under- or over-predict values relative to those experimentally determined values depending on the model. This current research has shown that nanocolloids associated with biosolids, specifically Al2O3, are mobile through saturated porous media. Given the ubiquity of nanocolloidal materials, particularly engineered nanomaterials, coupled with the expected increase in land-application of biosolids, a clear understanding of their transport and fate is prudent to understanding the potential impact these emerging pollutants may have on our surface and groundwater bodies.

Dans le cadre du regain d’activité pour la thermoélectricité, les matériaux skutterudite suscitent un vif intérêt du fait de leurs performances dans la gamme de température 400-800 K. L’étude des propriétés structurales et thermoélectriques de triantimoniures de cobalt partiellement remplies au néodyme, à l’ytterbium ou à l’indium, et partiellement substituées au nickel a ainsi été menée. Des composés denses et homogènes ont été obtenus via une technique de métallurgie des poudres. L’analyse conjointe des résultats de diffraction des rayons X et de microsonde de Castaing a permis de déterminer les limites de solubilité x des éléments remplisseurs dans Co4Sb12 : ainsi, xNd ~ 0,05 – 0,06, et xYb ~ xIn ~ 0,18. Dans le cas de l’ytterbium, nous avons montré par diffraction de neutrons sur poudre que ces atomes sont localisés au centre des cavités de la structure et qu’ils présentent un paramètre de déplacement atomique élevé. Les propriétés électriques (résistivité électrique, pouvoir thermoélectrique, effet Hall) et thermiques (conductivité thermique) ont été scrutées sur une vaste gamme de température (2 à 800 K). L’analyse des mesures, entre 2 et 800 K, a montré que plus la teneur en élément inséré est élevée, plus celui-ci a un impact bénéfique sur les propriétés thermoélectriques. Les performances maximales atteintes s’élèvent ainsi à ZT ~ 0,3 pour le composé Nd0,052Co4Sb12 à 800 K, ZT ~ 0,9 pour le composé In0,180Co4Sb12 à 710 K et ZT ~ 1 pour le composé Yb0,180Co4Sb12 à 800 K. L’optimisation de ces matériaux a alors été considérée via la substitution partielle du cobalt par du nickel. Nous avons montré que la présence de nickel augmente la concentration de porteurs de charge et modifie les mécanismes de diffusion onde ceux-ci. Dans le cas des composés partiellement remplis au néodyme, son impact sur les propriétés thermoélectriques est très bénéfique. Pour les composés à l’indium et à l’ytterbium, des compensations de l’influence du nickel sur les différents paramètres s’opèrent si bien que les performances thermoélectroniques globales du matériau ne présentent pas d’amélioration significative / In a context of renewed interest in thermoelectric compounds, skutterudite materials are an interesting target because of their good performances in the temperature range 400-800 K. The study of structural and thermoelectric properties of cobalt triantimonides partially filled with neodymium, ytterbium and indium, and partially substituted with nickel, has been undertaken. Dense and homogeneous samples have been obtained using a powder metallurgy technique. The joint analysis of X-ray diffraction and electroprobe microanalysis led to the determination of the solubility limit of the filler elements: xNd ~ 0,05 – 0,06, and xYb ~ xIn ~ 0,18. For ytterbium, we were able to prove by powder neutron diffraction technique that the atoms are localized at the centre of the structure and that they have a very high atomic displacement parameter. Electrical properties (electrical resistivity, thermal conductivity, Hall effect) and thermal properties (thermal conductivity) have been investigated on a very large range of temperature (2 to 800K). The exploitation of the measurements showed that the higher the quantity of each insertion element, the greater its beneficial impact on the thermoelectric properties. The best performances have been reached with ZT ~ 0,3 for Nd0,052Co4Sb12 at 800 K, ZT ~ 0,9 in the case of In0,180Co4Sb12 at 710 K and ZT ~ 1 for Yb0,180Co4Sb12 at 800 K. An optimisation was considered using the partial substitution of cobalt by nickel. The impact of nickel on the thermoelectric performances on ternary compounds was very different depending on the element. In the case of neodymium, the presence of nickel modified the diffusion mechanism of the carriers and its impact was very beneficial. For indium and ytterbium, the impact of nickel did not lead to any significant improvement

Nesta tese investigamos a partir de cálculos de primeiros princípios, dispositivos e componentes de dispositivos baseados em grafeno. Abordamos os campos da nanoeletrônica e da spintrônica. Dentro da nanoeletrônica investigamos: (i) propriedades de transporte de um nanotransistor de bicamada de grafeno na presença de um gate duplo. Demonstramos que sobre a ação de um campo elétrico externo, mesmo utilizando um gate da ordem de 10 nm, à temperatura ambiente e 4.5K uma corrente nula nunca é exibida. Esses resultados são explicados por um regime de tunelamento; (ii) propriedades eletrônicas e de transporte de multicamadas de grafeno em função do número de camadas e tipo de empilhamento entre elas. Mostramos que a estrutura eletrônica do sistema depende fortemente desse novo grau de liberdade de empilhamento. Na presença de um campo elétrico externo aplicado perpendicular ao sistema, o empilhamento do tipo Bernal nunca exibe um gap de energia, ao contrário do empilhamento romboédrico que exige um gap ajustável através da intensidade do campo. Mostramos também que é possível diferenciar os tipos de empilhamentos através da resistência do sistema e variando-se a temperatura; (iii) dentro das componentes de um nanotransistor mais realista, estudamos as propriedades eletrônicas e estruturais de: (a) bicamadas de grafeno sobre um substrato de nitreto de boro hexagonal. Neste sistema o limite de voltagens que podem ser aplicadas depende fortemente do número de camadas de h-BN e da direção do campo, onde quanto menos camadas maior é a voltagem que pode ser aplicada; (b) heteroestruturas compostas de bicamadas de grafeno, nitreto de boro hexagonal e cobre. Demonstramos que para uma aplicação direta em um dispositivo a configuração com uma bicamada de grafeno depositada sobre um substrato de h-BN e este conjunto sobre a superfície de cobre é a mais favorável. Nessa configuração é possível tanto controlar o gap na bicamada como a dopagem do sistema, sem a abertura de canais de condução através do dielétrico (h-BN). Dentro do campo da spintrônica estudamos: (i) propriedades de transporte das nanofitas de grafeno (GNR) (3,0) pristinas e dopadas com boro e nitrogênio. Para as GNR pristinas mostramos com os eletrodos em um alinhamento de spin anti-paralelo o sistema apresenta um comportamento de filtro de spin, onde para tensões de bias positivos/negativos somente o canal up/down conduz. Para as GNR dopadas com boro e nitrogênio, mostramos que as correntes para os diferentes canais de spin são não degeneradas ao longo de todo o intervalo de tensões aplicadas, apresentando desse modo um comportamento de filtro de spin; (ii) finalmente estudamos as propriedades de transporte de uma junção túnel magnética, composta de GNR intercaladas por uma nanofita de nitreto de boro hexagonal. Mostramos que esse sistema pode ser utilizado tanto como filtros de spin como elementos para dispositivos de magnetoresistência gigante, onde para este último a sua eficiência é muito mais pronunciada. / In this thesis we investigated by first principle calculations, devices and components of devices based on graphene. We covered the fields of nanoelectronics and spintronics. On the field of nanoelectronics we investigated: (i) the transport properties of a dual gate bilayer graphene nanotransistor. We showed that under the action of an external electrical field, even with a gate length of 10 nm, at room temperature and 4.5K a zero current is never exhibited. These results could be explained by a tunneling regime; (ii) the electronic and transport properties of few layer graphene, as function of the number and type of stacking of the layers. We show that the electronic structure strong deppends of the stacking order. On the presence of a external electrical field applied to the system, the Bernal stacking never presents a gap, contrary to the rombohedrical one, that posses a tuneable energy gap. Also we showed that is possible to differentiate the types of stacking by the resistance of the system and varying the temperature;(iii) for the components of a more realistic nanodevice, we study the structural and electronic properties of: (a) bilayer graphene over a hexagonal boron nitride substrate. We show that the voltages that could be applied to the system strongly depends of the number 0 layers and the direction of the field, where with more layers, smaller is the field; (b) heterostructures composed with bilayer graphene, hexagonal boron nitride and cooper. We show that for a direct application on a device, the better configuration is with a bilayer graphene over the hexagonal boron nitride, and this set over a cooper. In this configuration is possible to control both the gap and the doping of the system, without the creation of conducting channels through the dielectric (h-BN). On the field of spintronics, we study: (i) the transport properties (3,0) graphene nanoribbons pristines and doped with nitrogen and boron. For the pristine GNR we show that for the electrodes in an anti-parallel alignment the system presents a spin filter behavior, where for positive/negative bias the transport is only by up/down channel. For the GNR doped with nitrogen and boron we show that the current is non-degenerated in all range of voltages applied, presenting a spin filter behavior; (ii) finally, we study the transport properties of a magnetic tunnel junction, consisting of a GNR intercalated with a hexagonal boron nitride nanoribbon. We show that such system could be used both as a spin filter as a device that uses the the giant magnetoresistance effect, where for the last the system if more efficient.

Wu, Chin Kong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 122-131). / Abstract also in Chinese. / ABSTRACT (English) --- p.i / ABSTRACT (Chinese) --- p.iii / ACKNOWLEDGMENTS --- p.v / TABLE OF CONTENTS --- p.vi / Chapter CHAPTER 1 --- Introduction --- p.1 / Chapter 1.1 --- Organic light-emitting- diode (OLED) --- p.2 / Chapter 1.2 --- Organic photovoltaics --- p.5 / Chapter 1.3 --- Organic field-effect transistor --- p.10 / Chapter CHAPTER 2 --- Properties of organic semiconductor --- p.17 / Chapter 2.1 --- Organic semiconductors --- p.17 / Chapter 2.2 --- Electronic structure of organic semiconductors --- p.18 / Chapter 2.3 --- Disorder and traps in organic semiconductors --- p.19 / Chapter 2.4 --- Charge carriers transport in organic semiconductors --- p.20 / Chapter 2.4.1 --- Polaron model --- p.21 / Chapter 2.4.2 --- Scher-Montroll model --- p.21 / Chapter 2.4.3 --- Gaussian disorder model --- p.23 / Chapter 2.5 --- Metal/organic interfaces --- p.25 / Chapter CHAPTER 3 --- Experimental details --- p.28 / Chapter 3.1 --- Sample preparation --- p.28 / Chapter 3.1.1 --- Organic semiconductors used in this thesis --- p.28 / Chapter 3.1.2 --- Cleaning of substrate --- p.29 / Chapter 3.1.3 --- Deposition of organic layer --- p.29 / Chapter 3.1.4 --- Deposition of metal --- p.31 / Chapter 3.2 --- Electrical characterization methods --- p.32 / Chapter 3.2.1 --- Current density 一 voltage (J-V) measurement --- p.32 / Chapter 3.2.2 --- Dark Injection Space-Charge-Limited (DI-SCL) transient current measurement --- p.38 / Chapter 3.2.3 --- Temperature varied J-V measurement --- p.43 / Chapter 3.2.4 --- Admittance spectroscopy --- p.44 / Chapter CHAPTER 4 --- Charge transport properties in single-organic-layer devices --- p.51 / Chapter 4.1 --- Experimental scheme --- p.51 / Chapter 4.2 --- Experimental results and discussion --- p.53 / Chapter 4.2.1 --- J-V measurements --- p.53 / Chapter 4.2.1.1 --- MTDATA --- p.53 / Chapter 4.2.1.2 --- NPB --- p.59 / Chapter 4.2.2 --- DI-SCL transient current measurement --- p.64 / Chapter 4.2.3 --- Admittance spectroscopy --- p.68 / Chapter 4.2.3.1 --- MTDATA --- p.68 / Chapter 4.2.3.2 --- NPB --- p.75 / Chapter 4.3 --- Conclusion --- p.79 / Chapter CHAPTER 5 --- Charge transport properties in double-organic-layer devices with organic-organic heterojunction --- p.81 / Chapter 5.1 --- Introduction --- p.81 / Chapter 5.2 --- Experimental scheme --- p.82 / Chapter 5.3 --- Experimental results and discussion --- p.84 / Chapter 5.3.1 --- ITO/MTDATA/NPB/A1 device --- p.84 / Chapter 5.3.2 --- ITO/MTDATA/Alq3/LiF/Al device --- p.105 / Chapter 5.4 --- Conclusion --- p.115 / Chapter CHAPTER 6 --- Conclusions and future work --- p.101 / Chapter 6.1 --- Conclusions --- p.118 / Chapter 6.2 --- Future work --- p.120 / REFERENCES --- p.122

Chan, Wing Chit = (La₀.₆₇Ca₀.₃₃MnO₃/La₀.₃₀Ca₀.₇₀MnO₃/La₀.₆₇Sr₀.₃₃MnO₃/La₀.₃₀Ca₀.₇₀MnO₃)多層薄膜的電子輸運特性 / 陳榮捷. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / Abstract also in Chinese. / Chan, Wing Chit = (La₀.₆₇Ca₀.₃₃MnO₃/La₀.₃₀Ca₀.₇₀MnO₃/La₀.₆₇Sr₀.₃₃MnO₃/La₀.₃₀Ca₀.₇₀MnO₃) duo ceng bo mo de dian zi shu yun te xing / Chen Rongjie. / Abstract --- p.i / 論文摘要 --- p.iii / Acknowledgements --- p.iv / Table of Contents --- p.v / List of Figures --- p.viii / List of Tables --- p.xiii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Review of Magnetoresistance --- p.1 / Chapter 1.1.1 --- Giant magnetoresistance (GMR) --- p.4 / Chapter 1.1.2 --- Colossal magnetoresistance (CMR) --- p.7 / Chapter 1.2 --- Possible origins of CMR in manganites --- p.10 / Chapter 1.2.1 --- Double exchange mechanism --- p.10 / Chapter 1.2.2 --- Tolerance factor --- p.14 / Chapter 1.2.3 --- Jahn-Teller Distortion --- p.16 / Chapter 1.2.4 --- Magnetic phase diagram and charge ordering (CO) --- p.19 / Chapter 1.2.5 --- Phase separation and percolation theory --- p.23 / Chapter 1.2.6 --- Phase separation at the interfaces in thin films --- p.28 / Chapter 1.3 --- Our motivation --- p.29 / Chapter 1.4 --- Literature review of some manganite multilayer systems --- p.31 / Chapter 1.4.1 --- Ferromagnetic (FM)/antiferromagnetic (AF) multilayers --- p.31 / Chapter 1.4.2 --- Ferromagnetic (FM)/insulating oxides multilayers --- p.32 / Chapter 1.4.3 --- Ferromagnetic (FM)/ferromagnetic (FM) multilayers --- p.33 / Chapter 1.5 --- Scope of this thesis --- p.34 / References --- p.36 / Chapter Chapter 2 --- Instrumentation / Chapter 2.1 --- Thin film deposition --- p.40 / Chapter 2.1.1 --- Facing-target sputtering --- p.41 / Chapter 2.1.2 --- Vacuum system --- p.44 / Chapter 2.2 --- Characterization --- p.46 / Chapter 2.2.1 --- α-step profilometer --- p.46 / Chapter 2.2.2 --- x-ray diffraction (XRD) --- p.46 / Chapter 2.2.3 --- Resistance measurement --- p.49 / References --- p.51 / Chapter Chapter 3 --- Epitaxial growth and characterization of single layer thin films / Chapter 3.1 --- Introduction --- p.52 / Chapter 3.2 --- Fabrication of the sputtering targets --- p.52 / Chapter 3.3 --- Epitaxial growth of single layer thin films --- p.53 / Chapter 3.3.1 --- Substrate materials --- p.54 / Chapter 3.3.2 --- Deposition conditions --- p.55 / Chapter 3.3.3 --- Deposition procedures --- p.57 / Chapter 3.3 --- Characterization of single layer thin films --- p.58 / References --- p.63 / Chapter Chapter 4 --- La0 67Ca0.33MnO3/La030Ca0.70MnO3/La067Sr0.33MnO3/La0.30Ca070MnO3 multilayers / Chapter 4.1 --- Sample preparation --- p.64 / Chapter 4.2 --- Structure characterization of as-deposited samples --- p.68 / Chapter 4.3 --- Transport properties of as-deposited samples --- p.79 / Chapter 4.3.1 --- Series of samples with fixed Lao.3oCao.7oMn03 barrier layer thickness --- p.79 / Chapter 4.3.3.1 --- Samples with thin ferromagnetic layers: C20 and S20 series --- p.82 / Chapter 4.3.1.2 --- Series of samples with thick ferromagnetic layers --- p.87 / Chapter 4.3.1.3 --- Parallel resistors network --- p.96 / Chapter 4.3.2 --- Series of samples with varying Lao.3oCao.7oMn03 barrier layer thickness --- p.101 / Chapter 4.4 --- Discussion --- p.108 / References --- p.114 / Chapter Chapter 5 --- Conclusion / Chapter 5.1 --- Conclusion --- p.116 / Chapter 5.2 --- Future outlook --- p.119 / References --- p.121

Quantum dots (QDs), which are formed by a double barrier resulting in resonant-state electrons, are one of the ideal experimental tools to confine electrons and to study the tunneling of an electron through a double barrier in a one-dimensional transmission channel. In our research, we have two laterally coupled QDs in an Aharonov-Bohm (AB) ring geometry in which the coupling between two dots can be controlled. We use the tight-binding model to compute the exact transmission amplitude of an electron through the discrete quasi-bound states in coupled QDs embedded in an AB ring. We study the effect of magnetic flux on the transmission as well as explore how the inter-dot coupling changes the resonant states in QDs. We confirm that the lead-dot couplings involve the lifetime of the quasi-bound states in a symmetrical interference experiment. By tracing the position of the resonances of quasi-bound states, we can predict the shift of bonding and antibonding states for both single and multiple state-identical QDs as a function of energy levels and inter-dot coupling parameters. / Electron transport and resonance phenomena through QDs -- The tight-binding model -- Electron transport in a double quantum dot -- Transmission throught multiple states in a coupled quantum dot. / Department of Physics and Astronomy