This thesis presents the first fully tunable substrate integrated waveguide (SIW) filter implemented with PIN diodes and RF MEMS switches. The methodology for tuning SIW filters is explained in detail and is used to create three separate designs. Each SIW cavity is tuned by perturbing via posts connecting or disconnecting to/from the cavity's top metal layer. In order to separate the biasing network from the SIW filter, a three-layer PCB is fabricated using Rogers RT/duroid substrates. The first tunable design utilizes the Philips BAP55L PIN diode. This two-pole filter provides six frequency states ranging from 1.55 GHz to 2.0 GHz. Fractional bandwidth ranges from 2.3 percent – 3.0 percent with insertion loss and return loss better than 5.4 dB and 14 dB respectively for all frequency tuning states. The second tunable design utilizes the Radant RMSW-100 MEMS switch, providing six states ranging from 1.65 GHz to 2.1 GHz. Fractional bandwidth for this filter varies from 2.5 percent - 3.0 percent with insertion loss and return loss better than 12.4 dB and 16 dB respectively for all states. The third design utilizes the OMRON 2SMES-01 RF MEMS relay, providing fourteen states ranging from 1.19 GHz to 1.58 GHz. Fractional bandwidth ranges from 3.6 percent - 4.4 percent with insertion loss and return loss better than 4.1 dB and 15 dB respectively for all frequency states. Two of the three designs (Philips PIN diode and OMRON MEMS) produced good results validating the new SIW filter tuning methodology. Finally, to illustrate the advantage of microstrip planar structures integrated with SIW structures, low pass filters (LPFs) are implemented along the input and output microstrip-to-SIW transition regions of the tunable SIW filter. With minimal change to the overall filter size, this provides spurious suppression for the additional resonant modes inherently present in waveguide structures. The implemented design utilizes the same OMRON MEMS tunable SIW filter specifications. This two-pole tunable filter provides the same performance as the previous OMRON MEMS design with exception to an added 0.7 dB insertion loss and spurious suppression of -28 dB up to 4.0 GHz for all frequency tuning states.

Luminescent emission of non-fully conjugated homopolymers was successfully demonstrated as light emitting diodes (LEDs) in this research. Coil-like heterocyclic aromatic poly[2,2-(2,5-dialkyloxyphenylene)-4-4¡¦-hexafluoroisopropanebibenzoxazo- les] (6F-PBO-CnOTpA, with n = 10, 15, and 20) was synthesized, and polymer composites of 6F-PBO-CnOTpA was in-situ synthesized with acidified multi-wall carbon nanotube (MWNT- COOH). The non-fully conjugated coil-like heterocyclic aromatic homopolymer was synthesized by reacting 2,2,bis-(3-amino-4-hydroxy[henyl]-hexafluoropropane with 2,5-dialkyloxyterephthalic acid (CnOTpA) for 6F-PBO-CnOTpA, with n = 10, 15, and 20. In addition, MWNT was acidified for connecting the carboxylic group (-COOH) to reduce its aspect ratio and entropy induced aggregation. MWNT-COOH was analyzed using elemental analysis (EA) and viscometry to validate the effects of acidification period. The EA result seemed to suggest that the oxygen content increased, and the carbon and the hydrogen contents decreased with acidification period. The inherent viscosity (£binh) decreased according to acidification period suggesting that the aspect ratio was indeed decreased. A hole transport layer of PEDOT¡GPSS was applied for multi-layer LEDs,. The LEDs all showed a threshold voltage about 4 V also for the composites of 6F-PBO-CnOTpA in-situ polymerized with MWNT-COOH. The 6F-PBO-CnOTpA LEDs with and without MWNT-COOH showed an electroluminescence emission range of 400 to 750 nm.

Zinc oxide, with its direct wide bandgap and high exciton binding energy, is a promising material for optoelectronic devices. Quantum confinement effect and high surface to volume ratio of the nanowires imparts unique properties to them and makes them appealing for researchers. So far, zinc oxide nanowires have been used to fabricate various optoelectronic devices such as light emitting diodes, solar cells, sensors and photodetectors. To fabricate those optoelectronic devices, many different synthesis methods such as metal organic chemical vapor deposition, chemical vapor deposition, pulsed laser deposition, electrodeposition and hydrothermal method have been explored. Among them, hydrothermal method is the most feasible one in terms of simplicity and low cost. In this thesis, hydrothermal method was chosen to synthesize zinc oxide nanowires. Synthesized zinc oxide nanowires were then used as electrically active components in light emitting diodes and ultraviolet photodetectors. Hybrid light emitting diodes, composed of inorganic/organic hybrids are appealing due to their flexibility, lightweight nature and low cost production methods. Beside the zinc oxide nanowires, complementary poly [2- methoxy -5- (2- ethylhexyloxy) - 1,4 -phenylenevinylene] MEH-PPV and poly (9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) hole conducting polymers were used to fabricate hybrid light emitting diodes in this work. Optoelectronic properties of the fabricated light emitting diodes were investigated. Zinc oxide emits light within a wide range in the visible region due to its near band edge and deep level emissions. Utilizing this property, violet-white light emitting diodes were fabricated and characterized. Moreover, to take advantage over the responsivity of zinc oxide to ultraviolet light, ultraviolet photodetectors utilizing hydrothermally grown zinc oxide nanowires were fabricated. Single walled carbon nanotube (SWNT) thin films were used as transparent electrodes for the photodetectors. Optoelectronic properties of the transparent and flexible devices were investigated. A high on-off current ratio around 260000 and low decay time about 16 seconds were obtained. Results obtained in this thesis reveal the great potential of the use of solution grown zinc oxide nanowires in various optoelectronic devices that are flexible and transparent.

This dissertation introduces new technologies and techniques for low-cost phased arrays and scanning antennas. Special emphasis is placed on new approaches for low-cost millimeter-wave beam control. Several topics are covered. A novel reconfigurable grating antenna is presented for low-cost millimeter-wave beam steering. The versatility of the approach is proven by adapting the design to dual-beam and circular-polarized operation. In addition, a simple and accurate procedure is developed for analyzing these antennas. Designs are presented for low-cost microwave/millimeter-wave phased-array transceivers with extremely broad bandwidth. The target applications for these systems are mobile satellite communications and ultra-wideband radar. Monolithic PIN diodes are a useful technology, especially suited for building miniaturized control components in microwave and millimeter-wave phased arrays. This dissertation demonstrates a new strategy for extracting bias-dependent small-signal models for monolithic PIN diodes. The space solar-power satellite (SPS) is a visionary plan that involves beaming electrical power from outer space to the earth using a high-power microwave beam. Such a system must have retrodirective control so that the high-power beam always points on target. This dissertation presents a new phased-array architecture for the SPS system that could considerably reduce its overall cost and complexity. In short, this dissertation presents technologies and techniques that reduce the cost of beam steering at microwave and millimeter-wave frequencies. The results of this work should have a far-ranging impact on the future of wireless systems.

Optical beam induced current (OBIC) mapping has found wide-spread applications in characterizing semiconductor devices and integrated circuitry. In this study, we have used a two-photon scanning microscope to investigate InGaN light emitting diodes (LED). The defects induced by electrostatic discharge (ESD) can be clearly identified by DC-OBIC images. Additionally, we have combined an E-O modulator and a high frequency phase sensitive lock-in amplifier to conduct time-resolved study on the dynamical properties of the LEDs. The defects also exhibit different delay time when compared with the normal parts.

Recently, as a result of people around the world to actively encourage the creation of new businesses, so that the field of entrepreneurship research has become a field of study of foreign enterprises, the fastest growing part. In particular, Taiwan is now suffering because of the financial turmoil triggered by the economic recession crisis, global competition and rapidly changing industrial structure, but also to the urgent need to develop new industries to provide more employment opportunities. And as a result of the rise of emerging markets, a substantial increase in demand for the material, particularly in the industrial development of the oil must be used is in great demand, resulting in global crude oil stocks continued to decline. In addition, the sharp increase in carbon dioxide emissions, causing global warming, the greenhouse effect serious environmental problems are also plaguing the world, it is "the United Nations Framework Convention on Climate Change's Kyoto Protocol," signed. Under the influence of many factors in the world are looking into the use of resources in alternative energy and energy-efficient power-saving environmental protection products, including solar industry and light-emitting diode (LED) industry the most popular, so many of the new company set up R & D and production of related products. In this study, the production of LED Wafer and Chip professional manufacturer G company for the study, using SWOT Analysis, Five Forces analysis, expert interviews as research methods, analysis of LED current industry conditions and to explore the company's first business process and key success factors, and then find out the case, how can manufacturers in the highly competitive environment, the establishment of a unique business advantage to the follow-up for people wishing to enter the LED reference industrial companies. The case study found that the G company success and have the following six key factors: (1) business and industry pre-market assessment of the right; (2) a clear position; (3) product differentiation (niche products); (4) has a strong start-up team; (5) personality traits entrepreneurs; (6) of prudent financial control, and the scholars referred to the key factors of success in good agreement, therefore, present or future intention to enter the LED after industry into the role of manufacturers with a reference indicator .

Light-emitting diodes (LED) illumination takes considerable applications in nowadays daily lives due to the improvement on efficiency of the LED modules. The connections between the reliability and the lifetime, power efficiency, optical spectrum, and structure design of the LED modules are the major research topics. In this study, high-power LED modules encapsulated with different lens shapes after a thermal-aging test were studied experimentally and numerically. The results showed that the LED modules encapsulated with a hemispherical-shaped plastic lens exhibited a better lifetime due to their better thermal dissipation than those with cylindrical- or elliptical-shaped plastic lenses. In the case of 80¢J aging test, the lifetime of hemispherical-shaped lens was 1.5 times better than the cylindrical- or elliptical-shaped lenses. Decay of radiation pattern and optical spectrum of high-power LED modules fabricated by different manufacturers after a thermal-aging test were investigated experimentally and numerically. The results showed that the radiation pattern of the LED modules at the two view angles of ¡Ó (15o~75o) decreased more than the other angles as aging time increased. Due to the degradation of lens material after thermal aging, the center wavelength of the LED spectrum shifted 5 nm. Furthermore, the radius curvature of plastic lens was observed 6-70 £gm contraction as aging times increased. Both experimental and simulated results clearly indicated that improving the lens structure and lens material is essential to extend the operating life of the high-power LED modules. High-power phosphor-converted white-light-emitting diodes (PC-LEDs) with selected concentration and thickness of Ce:YAG phosphor-doped silicones were investigated to study the thermal degradation effect of the Ce:YAG phosphor-silicone layer. The experimental results showed that the lumen loss, chromaticity (CIE shift), and spectrum intensity reduction increased as the concentration of Ce:YAG phosphor doped silicone increased. We showed that 94% lumen loss was attributed to 5.5 wt% Ce:YAG doping and only 6% of the lumen loss was due to a 1mm thickness of silicone degradation. From practical points of view, we found that a lower doping concentration of the Ce:YAG phosphor in thin silicone is a better choice in terms of having less thermal degradation for use in packaging of the high-power PC-LEDs modules and is essential to extend the operating lifetime of the phosphor-based white LED modules.

This thesis describes the development of III-Nitride materials for light emitting applications. The goals of this research were to create and optimize a green light emitting diode (LED) and laser diode (LD). Metalorganic chemical vapor deposition (MOCVD) was the technique used to grow the epitaxial structures for these devices. The active regions of III-Nitride based LEDs are composed of InₓGa₁₋ₓN, the bandgap of which can be tuned to attain the desired wavelength depending on the percent composition of Indium. An issue with this design is that the optimal growth temperature of InGaN is lower than that of GaN, making the growth temperature of the top p-layers critical to the device performance. Thus, an InGaN:Mg layer was used as the hole injection and p-contact layers for a green led, which can be grown at a lower temperature than GaN:Mg in order to maintain the integrity of the active region. However, the use of InGaN comes with its own set of drawbacks, specifically the formation of V-defects. Several methods were investigated to suppress these defects such as graded p-layers, short period supper lattices, and native GaN substrates. As a result, LEDs emitting at ~532 nm were realized. The epitaxial structure for a III-Nitride LD is more complicated than that of an LED, and so it faces many of the same technical challenges and then some. Strain engineering and defect reduction were the primary focuses of optimization in this study. Superlattice based cladding layers, native GaN substrates, InGaN waveguides, and doping optimization were all utilized to lower the probability of defect formation. This thesis reports on the realization of a 454 nm LD, with higher wavelength devices to follow the same developmental path.

<p>Despite tremendous achievements, the field of conjugated polymers is still in its infancy, mimicking the more mature inorganic, i.e. silicon-based, technologies. We may though look forward to the realisation of electronic and electrochemical devices with exotic designs and device applications, as our knowledge about the fundamentals of these promising materials grow ever stronger. </p><p>My own contribution to this development, originating from an idea first put forward by my tutor, Professor Magnus Berggren, is a design for a switchable polymer-based diode. Its architecture is based on a modified version of a recently developed highly-rectifying diode,12 where an intermediate molecular layer has been incorporated in the bottom contact. Due to its unique ability to switch its internal resistance during operation, this thin layer can be used to shift the amount of (forward) current induced into the rectifying structure of the device, and by doing so shift its electrical characteristics between an insulating and a rectifying behaviour (as illustrated below). Such a component should be of great commercial interest in display technologies since it would, at least hypothetically, be able to replace the transistors presently used to address the individual matrix elements. </p><p>However, although fairly simple in theory, it proved to be quite the challenge to fabricate the device structure. Machinery errors and contact problems aside, several process routes needed to be evaluated and only a small fraction of the batches were successful. In fact, it was not until the very last day that I detected the first indications that the concept might actually work. Hence, several modifications might still be necessary to undertake in order to get the device to work properly.</p>

Thèse doctorat : Génie Electrique : Villeurbanne, INSA : 2003. / Titre provenant de l'écran-titre. Bibliogr. à la fin de chaque chapitre.