To see the other types of publications on this topic, follow the link: Organic semiconductors - Design and construction.
Dissertations / Theses on the topic 'Organic semiconductors - Design and construction'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Organic semiconductors - Design and construction.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Howells, Calvyn T. "Material and device design for organic photovoltaics." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6810.
Full textAbstract:
This thesis presents novel materials for photovoltaic conversion. The materials described are solution-processable organic semiconductors and have been used in the fabrication of organic photovoltaic cells (OPVs). The widely used PEDOT:PSS layer was investigated in P3HT and PTB7 photovoltaics. By doping, the efficiencies recorded were amongst the highest reported in the field using a conventional architecture. Two low band-gap BODIPY-based polymers were introduced and shown to have properties favourable for optoelectronics. Photovoltaics consisting solely of the polymers as the active component surpassed the performance expected without the use of an acceptor, indicating ambipolar behaviour, which was verified by charge carrier mobility measurements. When blended with an acceptor, the devices demonstrated a short-circuit current density similar to that of P3HT, a well-studied and successful OPV material. They also revealed a broad spectral response and were shown to operate as photodiodes. Two small molecules containing diketopyrrolopyrrole (DPP) and BODIPY were introduced and characterised. The addition of thiophenes red shifted the absorption but did not result in a sufficient bathochromic shift. Instead, a propensity to aggregate limited the performance. PLQY measurements showed the aggregation to quench luminescence. The study demonstrated the importance of controlling aggregation for efficient devices. Two solution-processable small molecules with a germanium-bridged spiro centre were investigated, and the molecular, electrochemical and optical properties discussed. The small molecule with shorter conjugation length exhibited an interesting packing motif shown to be favourable for charge transport. The mobility measurements were an order of magnitude higher than those reported for sexithiophene, a small molecule analogue, and the same order of magnitude as P3HT. The two-dimensional charge transporting nature of the material was verified with two independent techniques: time of flight (TOF) and organic field-effect transistor (OFET) measurements. The mobility of the material was found to vary with annealing, a result of morphological changes. These were studied with optical, electron and scanning probe microscopies. By controlling the morphology with the implementation of a well-defined annealing method, it was possible to improve the performance of OFETs and planar-heterojunction OPVs. Solution-processed bulk-heterojunction OPVs were fabricated, characterised and optimised with Ge spiro molecules. A PCE similar to that of P3HT, 2.66 %, was achieved for the one, whilst a PCE of 1.60 % was obtained for the other. The results are encouraging, and there is scope for improvement by increasing the overlap between the absorption and solar spectrum, for example.
2
Xu, Fei 1971. "Investigation of Ultratrace Metallic and Organic Contaminants in Semiconductor Processing Environments." Thesis, University of North Texas, 1997. https://digital.library.unt.edu/ark:/67531/metadc277845/.
Full textAbstract:
Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions and alkaline hydrogen peroxide solution was demonstrated using a silicon-based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open-circuit potential shift generated by the interaction between metallic ions and the silicon-based sensing surface. The new sensor can have practical applications in the on-line monitoring of microelectronic chemical processing. The detection of Ag+ content in KODAK waste water was carried out successfully by this novel sensor. Trace levels of organic impurities in the hydrofluoric acid solutions and in the cleanroom air were characterized by multiple internal reflection infrared spectroscopy (MIRIS) using an organics probe prepared directly from a regular silicon wafer.
3
Cheng, Kam-ho, and 鄭錦豪. "A study on novel organic semiconductor devices: light-emitting diode and thin-film transistor." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085519.
Full text
4
Wang, Kunlun. "Design and Synthesis of Novel Liquid Crystals and Organic Semiconductors." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1492881173762306.
Full text
5
Jones, Leighton Owen. "In silico design and synthesis of small-molecule intrinsic organic semiconductors for organic electronics." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17841/.
Full textAbstract:
On a global scale, the mass production of organic semiconductors for electronic applications in flexible display technology, among others, is linked to both research and consumer demand. To overcome challenges, the fabrication of the organic electronic devices has moved from high cost small-molecule vapour-phase deposition type techniques, to relatively low cost solution processing of the organic thin film transistors (OTFTs). Initial studies in this work focused on the modelling, prediction and synthesis of two dimensional planar structures. These studies probed the isomeric structures of pentacene. Quantum mechanics/density functional theory calculations found that at least five out of a total of 12 isomers (inclusive) are both air stable and have the same order of magnitude for the hole and electron rates of charge transfer as that of pentacene; suggesting that isomeric candidates of the initial target structure are worthy of thorough investigation. A second study on planar structures focused on novel and rationally designed molecules, six isomers inclusive, in an attempt to develop a challenging but high performing seven fused ring heteroacene. The study gave the interesting result that one structure is suitable for not just OTFTs, but also non linear optics, inferring that highly functional optoelectronic switches are possible from a single OTFT. A small library of rod-like structures were probed to contrast with the nature of the structures investigated so far. These contain linear components that separate the planar aromatic components in the molecules. It was discovered that these structures are highly flexible and soluble in common organic solvents, showing promise for applications as solution processed OTFTs. In summary, key discoveries of the study include (i) world-class candidates could be out-competed by their own isomers; (ii) new heteroacenes conceived could have bifunctional outputs for two separate fields in organic electronics; (iii) novel molecular rods were synthesised and found to have excellent solubility in common organic solvents, thereby enabling large scale fabrication of flexible display technologies.
6
Redic, Richard Charles. "Design and synthesis of potential organic optical switches." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/30865.
Full text
7
Yun, Ilgu. "Reliability modeling and parametric yield prediction of GaAs multiple quantum well avalanche photodiodes." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/12999.
Full text
8
Jagtap, Subodh Prakash. "Design and synthesis of and π-stacked conjugated oligomers and polymers." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47574.
Full textAbstract:
Interchain interactions between π-systems have a strong effect on the properties of conjugated organic materials that find application in devices such as light emitting diodes (OLEDs), organic photovoltaics (OPVs), and field effect transistors (FETs). We have prepared covalently-stacked oligo(1,4-phenylene ethynylene)s and oligo(1,4-phenylene vinylene)s to study the influence of chain-chain interactions on the electronic structure of closely packed conjugated units. These serve as models for segments of conjugated materials in thin film devices. Extension of this concept has allowed us to prepare multi-tiered systems that display the influence of pi-stacking. The stacked architectures were prepared by multi-step synthesis of the scaffolds, followed by metal-catalyzed cross coupling reactions (Sonogashira, Heck, Suzuki couplings) to incorporate the conjugated oligomers. The optical and electrochemical properties of these stacked compounds and polymers were compared to their unstacked linear counterparts. These studies provide a platform for the exploration of the nature of charge carriers and excitons in a broad class of materials that have significant potential in addressing challenges in power generation, lighting and electronics.
9
Chang, Chih-Hui 1967. "An Adaptive Linearization Method for a Constraint Satisfaction Problem in Semiconductor Device Design Optimization." Thesis, University of North Texas, 1999. https://digital.library.unt.edu/ark:/67531/metadc500248/.
Full textAbstract:
The device optimization is a very important element in semiconductor technology advancement. Its objective is to find a design point for a semiconductor device so that the optimized design goal meets all specified constraints. As in other engineering fields, a nonlinear optimizer is often used for design optimization. One major drawback of using a nonlinear optimizer is that it can only partially explore the design space and return a local optimal solution. This dissertation provides an adaptive optimization design methodology to allow the designer to explore the design space and obtain a globally optimal solution. One key element of our method is to quickly compute the set of all feasible solutions, also called the acceptability region. We described a polytope-based representation for the acceptability region and an adaptive linearization technique for device performance model approximation. These efficiency enhancements have enabled significant speed-up in estimating acceptability regions and allow acceptability regions to be estimated for a larger class of device design tasks. Our linearization technique also provides an efficient mechanism to guarantee the global accuracy of the computed acceptability region. To visualize the acceptability region, we study the orthogonal projection of high-dimensional convex polytopes and propose an output sensitive algorithm for projecting polytopes into two dimensions.
10
Akkarachaneeyakorn, Khrongkhwan. "The design, construction and properties of hybrid inorganic/organic biomaterials." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686249.
Full textAbstract:
The central themes of this thesis are focused on the design, construction and properties of hybrid inorganic/organic soft composites. The aim of the first experimental chapter was to synthesize plate-like hydroxyapatite (HA) in the presence of amino acids. The morphological effects of alanine, arginine, proline, lysine and glycine on calcium phosphate crystallization at neutral pH was studied. While the platelet morphologies of the produced colloids were influenced by the octacalcium phosphate transformation effect at the synthesis pH of 7, the amino acids were found to influence the highly positive surface charge and the size of nanoparticles, i.e. increasing the size of the side chain generally produced a progressive decrease in size of HA. As-prepared HA/alanine nanoparticles were then used to fabricate composite electrospun mats in two polymeric systems, i.e. chitosan and gelatine. Whereas HA nanoparticles were dominantly found at the surface of the chitosan fibres, they were embedded within the gelatine fibres. This was resulted from the repulsion of positively charged nanoparticles and positively charged chitosan fibres. The second experimental chapter detailed studies on a polymer/surfactant miniemulsion system as a synthetic medium for amorphous calcium phosphate particles for controlling the structure and morphology ofthe inorganic phase. The calcium phosphate nanofilaments were initially obtained inside the droplets before being redissolved to form spherical amorphous calcium phosphate. The growth process of the materials also continued from the centre to form filamentous structure outside the droplets and lengthened with time up to 300 nm. Subsequently, P123/DEHP/calcium phosphate organogel was produced by slow evaporation of the organic solvent from the reaction system. The range of gel was also prepared by varying the amount of mineral contents. As increasing the amount of calcium and phosphate salts, the structure of gel was disrupted and became phase separated due to crystallization of inorganic material. The produced hybrid gel was then successfully used in proof-of-concept studies demonstrating it could be used for the in vitro occlusion of exposed dentine tubules in a bovine model of tooth hypersensitivity. The final chapter investigated the use of Pickering emulsions (colloidosome) to prepare microreactors in water with the ability to catalyse the in situ formation of a supramolecular hydrogel matrix. Alkaline phosphatase encapsulated silica colloidosomes were transferred to FMOC-tyrosine phosphate containing solution. Counter diffusion of the FMOC-tyrosine phosphate across the nanostructured silica membrane resulted in reaction with the entrapped enzymes inside the colloidosomes and the formation of a Fmoc-tyrosine based hydrogel. Subsequently, the hydrogel was transferred into the extra-protocellular environment via a dissolution-reprecipitation process (Ostwald ripening). The reversible disassembly/reassembly properties of the hydrogel were also investigated by heating and cooling. The hydrogel structure interestingly changed by forming bundle of hydrogel packed inside the microcompartments while the external long filaments disappeared due to the polymerisation of saturated Fmoc-TyrOH monomer after diffusion into the microcompartments
11
Semyonov, Alexander N. "Design, Synthesis and Characterization of Fluorescent Dyes and Liquid Crystal Semiconductors." Kent State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=kent1153556141.
Full text
12
Cheung, Chi-chuen Cecil, and 張志泉. "Device design and fabrication of InGaP/GaAsSb/GaAs DHBTs." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29753727.
Full text
13
Jiang, Jinyue. "Design, Synthesis, and Properties of New Derivatives of Pentacene and New Blue Emitters." Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1145645147.
Full text
14
Kim, Taehoon. "Design, fabrication, and analysis of enhanced mobility silicon germanium transistors." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3034553.
Full text
15
Chen, Chunxiang. "Design, synthesis and characterization of new organic semi-conductors for photovoltaics." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30108/document.
Full textAbstract:
Les cellules photovoltaïques organiques sont une technologie prometteuse pour répondre aux besoins futurs en énergie. Elles présentent de faibles coûts de production, peuvent être réalisées sur substrats flexibles et s'intègrent dans des dispositifs légers. Une voie d'amélioration du rendement de photoconversion est la conception de nouvelles molécules actives présentant des propriétés structurales optimisées. Le présent travail s'inscrit dans cette dynamique: sur la base de calculs utilisant la théorie de la fonctionnelle de la densité, de nouveaux semiconducteurs organiques ont été conçus puis synthétisés. Pour cela, des techniques de synthèses les plus économiques et les moins polluantes possible ont été mises en œuvre. Ainsi, le couplage du benzothiadiazole avec le thiophène carboxhaldéhyde par hétéroarylation directe sans additif ni ligand est utilisé avec succès pour la première fois selon des techniques de chimie verte. Cinq molécules sont ainsi isolées en seulement deux étapes. L'étude de leurs propriétés optiques et électroniques par différentes techniques spectroscopiques (UV/vis, fluorescence) et par électrochimie, de leurs propriétés thermiques, et de leur aptitude à s'auto-organiser ont permis de révéler leur aptitude prometteuse pour une utilisation en photovoltaïque organique. Une série de molécules dérivées du fragment dithiénosilole (DTS) ont été également étudiées par calculs de DFT. Les résultats obtenus montrent que ces dérivés présentent des largeurs de bande interdite très faibles, ce qui constitue un atout pour leur utilisation en cellule photovoltaïque. Ces résultats ont par conséquent motivé leur synthèse. Enfin, un travail purement théorique a été réalisé sur des molécules dérivées des subphthalocyanines de bore. Les calculs effectués révèlent des propriétés électroniques originales pour ces nouveaux matériaux qui devraient mener à des performances intéressantes pour le photovoltaïque organique, ouvrant ainsi la voie vers des matériaux innovants et prometteursOrganic solar cells appear as a promising technology to meet future energy requirements, owing to their low production costs, their great flexibility and their ability to be integrated into light devices. Currently, they exhibit modest performances in photoconversion, thus new active molecules with optimized structural properties need to be developed. This work comes in that aim: on the basis of theoretical calculations with density functional theory, new organic semiconductors have been designed and synthesized. For this, the more economical and cleaner syntheses techniques have been employed. Thus, the coupling of the benzothiadiazole with thiophene carboxhaldehyde via direct heteroarylation without additive nor ligand is performed with success for the first time. According to green chemistry techniques, five molecules are thus isolated in only two steps. The study of their optical and electronic properties by means of different spectroscopic techniques (UV/vis, fluorescence) and electrochemistry, of their thermal properties, and of their ability to self-organize have revealed their promising abilities for use in organic photovoltaics. A series of small molecules based on dithienosilole (DTS) core have also been designed via DFT computations. The calculations show their considerable low bandgap. Their syntheses have been conducted. It anticipates their promising potential for organic photovoltaic applications. Finally, a purely theoretical work has been completed on molecules derived from boron subphthalocyanines. The calculations predict interesting electronic properties for these new materials that may lead to promising performances in organic photovoltaics, paving the way for innovative materials
16
Pandya, Hermona K. "Molecular design of organic semiconductors for electronic devices and their application in flexible light emitting diodes." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.08 Mb., 120 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3205439.
Full text
17
Kramer, Illan. "Fabrication and characterization of a hybrid heterojunction composed of N-type silicon and PEDOT:PSS." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99774.
Full textAbstract:
A hybrid organic/inorganic heterojunction has been fabricated using an n-type silicon wafer (< 111 >, 3 < ρ < 6 Ω · cm) and a p-type polymer, PEDOT:PSS (ρ = 1 Ω · cm). Standard fabrication techniques such as vacuum deposition and spin coating are required for fabrication and have been employed. I-V characteristics have been measured under both dark and illuminated conditions for different thicknesses of PEDOT:PSS as defined by the spin rate at which the polymer has been spin coated. The data has been analyzed and figures of merit such as series resistance, short circuit current, open circuit voltage, fill factor and efficiency have been calculated. The efficiency ranges to values as high as 0.63%, while the fill factor has been observed to be as high as 57%, both of which are improvements on previously reported hybrid heterojunctions built on n-type silicon wafers.
18
Sandström, Andreas. "Design and Fabrication of Light-Emitting Electrochemical Cells." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-79544.
Full textAbstract:
Glödlampan, en gång symbolen för mänsklig uppfinningsförmåga, är idag på väg att försvinna. Lysdioder och lågenergilampor har istället tagit över då dessa har betydligt längre livstid och högre effektivitet. Den tidigare så hyllade glödlampan anses numera vara en miljöbov, och förbud och restriktioner mot den blir allt vanligare. Trots detta så är de nya alternativen bara att betrakta som provisoriska steg på vägen mot en ideal ljuskälla, som idag tyvärr inte existerar. Lågenergilampor innehåller exempelvis kvicksilver, och utgör därmed ett direkt hot mot en användares hälsa. Både lysdioder och lågenergilampor består även av höga halter av andra tungmetaller, och är väldigt komplicerade att tillverka. Återvinning är därför ett måste, och en fullödig energibesparingsanalys måste ta hänsyn till den betydande energin som går åt vid tillverkningen. Till viss del kan detta lösas genom att göra komponenterna små och ljusstarka, men för att göra en sådan belysning angenäm används istället utrymmeskrävande och ofta energislukande lampskärmar. Lysdioder och lågenergilampor är helt enkelt bra, men långt ifrån perfekta.All elektronisk utrustning är idag beroende av metaller och inorganiska halvledare, vilket gör återvinning viktig och tillverkning komplicerad. Detta är kanske på väg att ändras då även organiska material, t.ex. plast, har visat sig kunna ha elektroniska egenskaper. Idag är organisk elektronik ett hett forskningsområde där material med liknande egenskaper som plast, fast med funktionella elektroniska egenskaper, undersöks och appliceras. Något som gör organiska material extra intressanta är att många kan lösas upp i vätskor, vilket möjliggör för skapandet av bläck. Detta leder i sin tur till möjligheter för användandet av storskaliga trycktekniker, t.ex. tidningspressar och bläckstråleskrivare, vilka leder till en stor kostnadsreduktion och förenklad tillverkning av lysande komponenter. Idag har plast redan ersatt många andra material i en mängd olika tillämpningar. Plastflaskor är vanligare än glasflaskor, och ylletröjor konkurerar idag med kläder gjorda av fleece och andra syntetiska fibrer. Med ljusemitterande plast finns det helt klart en möjlighet att en liknande utveckling kan ske även för lampor.Den här avhandlingen fokuserar på den fortsatta utvecklingen av den ljusemitterande elektrokemiska cellen (LEC), som 1995 uppfanns av Pei et al. LEC-tekniken använder sig av organiska halvledare för att konvertera elektrisk ström till ljus, men även en elektrolyt som möjliggör elektrokemisk dopning. Detta förbättrar den organiska halvledarens elektroniska egenskaper signifikant, vilket leder till mindre resistans och högre effektivitet hos den färdiga lysande komponenten.Visionen för denna och besläktade tekniker har sedan länge varit förverkligandet av en lysande tapet. Den här avhandlingen har försökt närma sig denna vision genom att visa hur en LEC kan uppnå hög effektivitet och lång livslängd, och samtidigt tillverkas i luft med storskaliga produktionsmetoder. Orsaker till en tidigare begränsad livslängd har identifierats och minimerats med hjälp av nya komponentstrukturer och materialformuleringar. En inkapslingsmetod presenteras också, vilken skyddar komponenten från syre och vatten som annars lätt reagerar med det dopade organiska materialet. Detta resulterar i en signifikant förbättring av livslängden.Genom att använda slot-die bestrykning och sprayning, båda kompatibla med rulle-till-rulle tillverkning, har möjligheter för storskalig produktion demonstrerats. Slutligen har en speciell metod för spraymålning av stora lysande ytor utvecklats.The incandescent light bulb, once the very symbol for human ingenuity, is now being replaced by the next generation of lighting technologies such as the compact fluorescent lamp (CFL) and the light emitting diode (LED). The higher efficiencies and longer operational lifetimes of these new sources of illumination have led to the demise of the classic traditional bulb. However, it should be pointed out that the light sources that are taking over are better, but not perfect. The complex high-voltage electronic circuits and health hazardous materials required for their operation make them far from a sustainable eco-friendly option. Their fabrication is also complex, making the final product expensive. A new path forward might be through the use of plastics or other organic materials. Though not traditionally seen as electronically active, some organic materials do behave like inorganic semiconductors and substantial conductivity can be achieved by doping. Since plastics can be easily molded into complex shapes, or made into an ink using a solvent, it is expected that organic materials could revolutionize how we fabricate electronic devices in the future, and possibly replace inorganic crystals in the same way as plastics have replaced glass and wool for food storage and clothes. This thesis has focused on the light-emitting electrochemical cell (LEC), which was invented by Pei et al. in 1995. It employs organic semiconductors that can convert electricity to light, but also an electrolyte that further enhances the electronic properties of the semiconductor by allowing it to be electrochemically doped. This allows light-emitting films to be driven by a low-voltage source at a high efficiency. Unfortunately, the electrolyte has been shown to facilitate rapid degradation of the device under operation, which has historically severely limited the operational lifetime. Realizing the predicted high efficiency has also proven difficult. The purpose of this thesis is to bridge the gap between the LEC and the CFL. This is done by demonstrating efficient devices and improved operational lifetimes. Possible degradation mechanisms are identified and minimized using novel device architectures and optimized active layer compositions. An encapsulation method is presented, and shown to increase the LEC stability significantly by protecting it from ambient oxygen and water. The thesis further focuses on up-scaled fabrication under ambient air conditions, proving that light-emitting devices are compatible with solution-based and cost-efficient printing. This is achieved by a roll-to-roll compatible slot-die coating and a novel spray-depositing technique that alleviates problems stemming from dust particles and phase separation. A practical ambient air fabrication and a subsequent operation of light-emitting electrochemical cells with high efficiency are thus shown possible.
19
Fu, Boyi. "Design and syntheses of hole and electron transport donor-acceptor polymeric semiconductors and their applications to organic field-effect transistors." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54868.
Full textAbstract:
The π-conjugated organic and polymeric semiconducting materials have attracted much attention in the past years due to their significant potential in applications to electronic and optoelectronic devices including organic field-effect transistors (OFETs), organic photovoltaics (OPVs), and organic light-emitting diodes (OLEDs), etc. Yet, organic and polymeric semiconductors still have challenges associated with their relatively low charge carrier (hole and electron) transport mobilities and ambient stability in OFET applications.
This dissertation discusses the molecular engineering on backbones and side-chains of π-conjugated semiconducting polymers to enhance the hole and electron field-effect mobilities. Three donor-acceptor copolymers, the hole transport (p-type) poly(hexathiophene-co-benzo- thiazole) (PBT6), the hole transport poly(thiophenes-benzothiadiazole-thiophenes-diketopyrrolo- pyrrole) (pTBTD), and the electron transport (n-type) poly(dithieno-diketopyrrolopyrrole-bithiazole) (PDBTz) have been developed. Besides, the effect of polymer side chains on polymer solution-processability and charge carrier transport properties was systematically investigated: a side chain 5-decylheptadecyl having the branching position remote from the polymer backbone merges the advantages of the improved solubility from traditional branched side chains in which the branch chains are close to polymer backbone and the effective π-π intermolecular interactions commonly associated with linear side chains. This indicates the potential of side chain engineering to facilitate the charge carrier transport performance of organic and polymeric semiconductors. Additionally, PDBTz solution-processing to OFETs based on non-halogenated solvents (xylenes and tetralin) was studied. The resultant thin-film OFET devices based on non-halogenated solvents exhibited similar film morphology and field-effect electron mobilities as the counterparts based on halogenated solvents, indicative of the feasibility of developing high mobility OFET devices through more environmentally-benign processing.
20
Moudgil, Karttikay. "Design and development of dimeric sandwich compounds as n-dopants for organic electronics." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54958.
Full textAbstract:
Electrical doping of organic semiconductors with molecular oxidants (p-type) or reductants (n-type) can greatly improve charge injection and conductivity in devices. Simple one electron reductants that are capable of reducing most electron-transport materials will inevitably also be sensitive to reaction with oxygen. Coupling electron transfer step with bond breaking/ making processes in principle can address this problem. The rhodocene dimer and related ruthenium and iridium dimeric sandwich compounds have been discussed as example of such n-dopants, reducing a variety of organic semiconductors to the corresponding radical anions, while forming monomeric cations. This class of n-dopants can be used in both vapor- and solution-processed devices, and the dopant monomer cations are large and, therefore, fairly stable with respect to diffusion. This thesis focused on increasing the utility of these and related electrical dopants. In order to reduce various electron-transport materials with lower electron affinities, which are frequently used in OLEDs, strategies and limitations to develop stronger n-dopants is discussed. Controlling the kinetics of the dopant / semiconductor reactions to allow film processing in ambient conditions, with activation of the dopants being carried out thermally or photochemically in subsequent steps is presented. An approach to covalently tether monomeric cations with themselves, surfaces or electron-transport materials is described. Electrochemical studies that further our understanding of dopant kinetics and thermodynamics is described. The dimer dopant chemistry is also compared to the corresponding hydride-reduced complexes of the cations and manganese tricarbonyl benzene dimer. The directions for future dopant design with improved properties is discussed.
21
Kas, Onur Y. "Design, synthesis and characterization of bio/electroactive hybrids confining chromophores in dilute solutions using a helical peptide template /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 148 p, 2008. http://proquest.umi.com/pqdweb?did=1459918061&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full text
22
Williams, Lawrence Joseph 1968. "Design and construction of organic crystals: Orthogonal recognition of pioperazinediones derived from unnatural alpha-amino acids." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282281.
Full textAbstract:
A paradigm and theoretical model for the design and construction of acentric crystalline solids is presented. In theory, molecular assembly in a predetermined arrangement will result for molecules that possess and participate in three chemically and geometrically orthogonal intermolecular interactions. A class of piperazinediones was designed to possess such orthogonal recognition elements and may provide an appropriate scaffold for the rational design of molecular building blocks for construction of acentric crystals. The topography and conformational rigidity of this scaffold limit packing options, which facilitate prediction of crystal structures from consideration of readily identified forces associated with three orthogonal recognition elements. Recognition elements can be introduced and modified by changing the functional groups on the scaffold via chemical synthesis. Structural variability facilitates exploration and exploitation of these molecules. A family of organic molecules that satisfy many of the conditions of the theoretical model is described and evaluated on the basis of their design, synthesis, and characterization.
23
Chen, Lüzhou, and 陈绿洲. "Optical design of organic solar cells by 3-D modeling of device structures." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196035.
Full textAbstract:
Organic solar cells (OSCs) have attracted intense attention in recent years due to their advantages of low cost, easy fabrication, and high flexibility compared to its inorganic counterparts. However, due to the conflicts between the short diffusion length of excitons and long absorption length of incident photons, the thickness of OSCs is typically thin, and thus power conversion efficiency (PCE) is generally lower than traditional silicon solar cells. Therefore, an exquisite design of light trapping schemes is essential to the PCE improvement. Generally, physical guideline of light trapping involves two main approaches: geometric optics methods and wave optics methods. The former aims at elongating optical path inside the photoactive layer and thus enhancing photon absorption. For organic thin film solar cells with typical active layer thickness of 100 nm-200 nm, which is in subwavelength scale, we cannot investigate light harvesting mechanism simply by the geometric optics methods and instead wave optics properties should be considered.
In this thesis, two different light trapping enhancement designs are proposed. In order to simulate these structures, we built up programs for absorption power calculation based on scattering matrix method (SMM) by rigorously solving Maxwell’s equations. It is worth to point out that, different from the widely-used calculation method by Absorption = 1-Transmission-Reflection, our algorithm can extract the net optical absorption of the active layer rather than the whole OSCs. This improvement is very important because metal absorption, which does not contribute to exciton generation, can be excluded from the result.
In Chapter 3, design of organic solar cell incorporating periodically arranged gradient type active layer is presented. This design can enhance light harvesting with patterned organic materials themselves (i.e. self-enhanced active layer design) to avoid degrading electrical performance in contrast to introducing inorganic concentrators into the active layers such as silicon and metallic nanostructures. Our numerical results show that the OSC with a self-enhanced active layer, compared with the conventional planar active layer configuration, has broadband and wide-angle range absorption enhancement due to better geometric impedance matching and prolonged optical path.
In Chapter 4, OSC with interstitial lattice patterned metal nanoparticles (NPs) is proposed, which can improve the light blocking of traditional square lattice patterned NPs structure and achieve broadband absorption enhancement. Compared to square lattice design, the plasmonic mode couplings between individual NPs in the interstitial lattice are more versatile and much stronger. Moreover, plasmonic modes can couple to the guided modes, resulting in large enhancement factor at some wavelengths. These works provide a theoretical foundation and engineering reference for high performance OSC designs.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
24
Williams, Frances R. "Monitoring and Control of Semiconductor Manufacturing Using Acoustic Techniques." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5278.
Full textAbstract:
Since semiconductor fabrication processes require numerous steps, cost and yield are critical concerns. In-situ monitoring is therefore vital for process control. However, this goal is currently restricted by the shortage of available sensors capable of performing in this manner. The goal of this research therefore, was to investigate the use of acoustic signals for monitoring and control of semiconductor fabrication equipment and processes. Currently, most methods for process monitoring (such as optical emission or interferometric techniques) rely on "looking" at a process to monitor its status. What was investigated here involved "listening" to the process. Using acoustic methods for process monitoring enhances the amount and sensitivity of data collection to facilitate process diagnostics and control.
A silicon acoustic sensor was designed, fabricated, and implemented as a process monitor. Silicon acoustic sensors are favorable because of their utilization of integrated circuit and micromachining processing techniques; thus, enabling miniature devices with precise dimensions, batch fabrication of sensors, good reproducibility, and low costs. The fabricated sensor was used for in-situ monitoring of nickel-iron electrochemical deposition processes. During this process, changes occur in its plating bath as the alloy is being deposited. It is known that changes in the process medium affect the acoustic response. Thus, the sensor was implemented in an electroplating set-up and its response was observed during depositions. By mapping the sensor response received to the film thickness measured at certain times, a predictive model of the plated alloy thickness was derived as a function of sensor output and plating time. Such a model can lead to real-time monitoring of nickel-iron thickness.
25
Bodepudi, Srikrishna Chanakya. "Design and construction of ultrahigh vacuum system to fabricateSpintronic devices, fabrication and characterization of OMAR (organic magnetoresistance) devices." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-19583.
Full textAbstract:
This thesis concerns design and construction of an ultra high vacuum chamber to fabricate and characterize spintronic devices. The long term intention is to fabricate spin valve structures with V[TCNE]2 (hybrid organic inorganic semiconductor room temperature magnet) sandwiched between two ferromagnetic electrodes, which requires better than 10-8mbar of vacuum. Due to an uncured leak in the chamber, the current vacuum is limited to 4*10-7mbar. The V[TCNE]2 thin film prepared in this vacuum, oxidized completely by the presence of oxygen during the film growth. Organic magnetoresistance (OMAR) devices which are simple organic diode structures were fabricated and characterized, as they are compatible with high vacuum conditions. A magnetoresistance measurement set up was arranged and the possible problems in fabrication and characterization are analyzed.
To fabricate OMAR devices-ITO/P3HT/Al, RR-P3HT (regio regular poly (3-hexylthiophene)) an effective hole transport polymer with higher hole mobilities was used as an active layer and Al (aluminum) as a cathode. A thermal evaporation setup was added to the vacuum chamber to evaporate Al electrodes. The devices were kept in argon and vacuum environments, while characterizing in dark to suppress the exitons generated by photo illumination. The Organic magnetoconductance of about 1% is observed for the less concentration P3HT (3mg/1ml), and significantly improved to -23% for the high concentration P3HT (10mg/ml) solution. The results support that the negative magnetoconductance is due to the formation of bipolaron under the influence of an external magnetic field.
Finally, suggestions to improve the performance of the vacuum chamber to fabricate and characterize the spintronic devices and OMAR devices are presented.
26
Johnson, Phillip. "Design and automation of MEDUSA (Materials and Electronic Device Universal System Analyzer)." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03242009-040444/.
Full text
27
Levell, Jack William. "Material and device design for organic optoelectronics." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2066.
Full textAbstract:
This thesis describes investigations into the photophysical properties of luminescent materials and their application in optoelectronic devices such as light emitting diodes and photodetectors. The materials used were all solution processable because of the interest in low cost processing of organics. I have investigated the photophysics of 1,4,5,8,9,12-hexamethyltriphenylene, a triphenylene derivative which has its luminescence enhanced by the addition of methyl groups. These groups change the planar shape of the triphenylene molecule into a twisted one, changing the symmetry of the molecule and increasing its dipole moment in absorption and emission by ~4 fold. This increased its rate of radiative deexcitation by ~20 times. In addition, the twisted shape of the molecule prevents intermolecular interactions and concentration effects from affecting the luminescence. This results in an efficient solid-state photoluminescence quantum yield of 31%. This thesis also includes an investigation into phosphorescent polymer dendrimers, designed to have suitable viscosities in solution for inkjet printed OLED applications. A photophysical study of the intra-chain aggregation effects on the luminescence was undertaken in both homopolymers and copolymers with high energy gap spacer units. Using double dendrons to increase the steric protection of the luminescent cores, the best homopolymers achieved 12.1% external quantum efficiency (39.3 cd/A) at 100 cd/m² brightness and the best co-polymer achieved 14.7% EQE (48.3 cd/A) at 100 cd/m². This compares favourably with 11.8% EQE for the best phosphorescent polymer and 16% for the best solution processed dendrimer OLED previously reported. Finally I have applied a solution processed enhancement layer to silicon photodiodes to enhance their ultraviolet response. Using a blend of materials to give favourable absorption and emission properties, 61% external quantum efficiency was achieved at 200 nm, which is better than the 20-30% typical for vacuum deposited lumogen enhancement layers used commercially.
28
Zhang, Di, and 张笛. "Transparent electrode design and interface engineering for high performance organic solar cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/202360.
Full textAbstract:
With the growing needs for energy, photovoltaic solar cells have attracted increasing research interests owing to its potentially renewable, feasible and efficient applications. Compared to its inorganic counterparts, organic solar cell (OSC) is highly desirable due to the low-cost processing, light weight, and the capability of flexible applications. While rapid progress has been made with the conversion efficiency approaching 10%, challenges towards high performance OSCs remain, including further improving device efficiency, fully realizing flexible applications, achieving more feasible large-area solution process and extending the stability of organic device.
Having understood the key technical issues of designing high performance OSCs, we focus our work on (1) introducing flexible graphene transparent electrodes into OSCs as effective anode and cathode; (2) interface engineering of metal oxide carrier transport layers (CTLs) in OSCs through incorporating plasmonic metal nanomaterials ;(3)proposing novel film formation approach for solution-processed CTLs in OSCs in order to improve the film quality and thus device performance.
The detailed work is listed below:
1. Design of transparent graphene electrodes for flexible OSCs
Flexible graphene films are introduced into OSCs as transparent electrodes, which complement the flexibility of organic materials. We demonstrate graphene can function effectively as both the anode and cathode in OSCs:
a) Graphene anode: we propose an interface modification for graphene to function as anode as an alternative to using aconventional polymer CTL. Using the proposed interfacial modification, graphene OSCs show enhanced performance. Further analysis shows that our approach provides favorable energy alignment and improved interfacial contact.
b) Graphene cathode: efficient OSCs using graphene cathode are demonstrated, using a new composite CTL of aluminum-titanium oxide (Al-TiO2).We show that the role of Al is two-fold: improving the wettability as well as reducing the work function of graphene. To facilitate electron extraction, self-assembledTiO2is employed on the Al-covered graphene, which exhibits uniform morphology.
2. Incorporation of plasmonic nanomaterialsinto the metal oxide CTLinOSCs
By incorporating metallic nanoparticles (NPs) into the TiO2CTLin OSCs, we demonstrate the interesting plasmonic-electrical effect which leads to optically induced charge extraction enhancement. While OSCs using TiO2CTL can only operate by ultraviolet (UV)activation, NP-incorporated TiO2enables OSCs to perform efficiently at a plasmonic wavelength far longer than the UV light. In addition, the effciency of OSCs incorporated with NPs is notably enhanced. We attribute the improvement to the charge injection of plasmonically excited electrons from NPs into TiO2.
3. Formation of uniform TiO2CTLfor large area applications using a self-assembly approach
A solution-processed self-assembly method is proposed for forming large-area high-quality CTL films. Owing to the careful control of solvent evaporation, uniform film is formed, leading to enhanced OSC performance. Meanwhile, our method is capable of forming large-area films. This approach can contribute to future low-cost, large-area applications.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
29
Dowlatabadi, Ahmad Baghai. "A high speed, high resolution, self-clocked voltage comparator in a standard digital CMOS process." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/14794.
Full text
30
Chin, Shaoan. "MOS-bipolar composite power switching devices." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54275.
Full textAbstract:
Two MOS-Bipolar composite power semiconductor switching devices are proposed and experimentally demonstrated. These devices feature high voltage and high current capabilities, fast switching speeds, simple gate drive requirements, savings in chip area, reverse bias second breakdown ruggedness and large safe operating areas. Application characteristics of the devices for high frequency power inverter circuits are discussed. Monolithic integration of the two composite devices are also proposed.Ph. D.
31
Wang, Xiaoyang. "Design, Construction and Investigation of Synthetic Devices for Biological Systems." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1314041031.
Full text
32
Pun, Chiu-ho, and 潘昭豪. "Estimation of the impact of patterning error on MOSFET by conformal mapping." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30730831.
Full text
33
Kumta, Prashant Nagesh 1960. "RAPID SOLIDIFICATION PROCESSING OF INDIUM GALLIUM ANTIMONIDE ALLOYS." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276468.
Full textAbstract:
Solidification from the melt is an essential step in nearly all conventional processes to produce bulk materials for industrial applications. Rapid quenching from the liquid state at cooling rates of 102 to 106K/s or higher has developed into a new technology for processing novel materials. InxGa1 - xSb a ternary III-V compound semiconductor was synthesized by using the rapid spinning cup (RSC) technique. Several compositions of these alloys were batched and cast into ingots in evacuated sealed quartz tubes. These ingots were then melted and ejected onto a rapidly rotating copper disk. This resulted in the generation of flakes or powders depending on the rpm of the disk. Microstructural characterization of the flakes and powders was performed using XRD, SEM and TEM. Efforts were also made to measure the bulk resistivity of the annealed flakes to see the effect of annealing on ordering of the phases.
34
Woody, Kathy Beckner. "Design, synthesis and characterization of self-assembling conjugated polymers for use in organic electronic applications." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43627.
Full textAbstract:
Conjugated polymers comprise some of the most promising materials for new technologies such as organic field effect transistors, solar light harvesting technology and sensing devices. In spite of tremendous research initiatives in materials chemistry, the potential to optimize device performance and develop new technologies is remarkable. Understanding relationships between the structure of conjugated polymers and their electronic properties is critical to improving device performance. The design and synthesis of new materials which self-organize into ordered nanostructures creates opportunities to establish relationships between electronic properties and morphology or molecular packing. This thesis details our progress in the development of synthetic routes which provide access to new classes of conjugated polymers that contain dissimilar side chains that segregate or dissimilar conjugated blocks which phase separate, and summarizes our initial attempts to characterize these materials. Poly(1,4-phenylene ethynylene)s (PPEs) have been used in a variety of organic electronic applications, most notably as fluorescent sensors. Using traditional synthetic methods, asymmetrically disubstituted PPEs have irregular placement of side chains on the conjugated backbone. Herein, we establish the first synthetic route to an asymmetrically substituted regioregular PPEs. The initial PPEs in this study have different lengths of alkoxy side chains, and both regioregular and regiorandom analogs are synthesized and characterized for comparison. The design of amphiphilic structures provides additional opportunities for side chains to influence the molecular packing and electronic properties of conjugated polymers. A new class of regioregular, amphiphilic PPEs has been prepared bearing alkoxy and semifluoroalkoxy side chains, which have a tendency to phase separate. Fully conjugated block copolymers can provide access to interesting new morphologies as a result of phase separation of the conjugated blocks. In particular, donor-acceptor block copolymers that phase separate into electron rich and electron poor domains may be advantageous in organic electronic devices such as bulk heterojunction solar cells, of which the performance relies on precise control of the interface between electron donating and accepting materials. The availability of donor-acceptor block copolymers is limited, largely due to the challenges associated with synthesizing these materials. In this thesis, two new synthetic routes to donor-acceptor block copolymers are established. These methods both utilize the catalyst transfer condensation polymerization, which proceeds by a chain growth mechanism. The first example entails the synthesis of a monofunctionalized, telechelic poly(3-alkylthiophene) which can be coupled to electron accepting polymers in a subsequent reaction. The other method describes the first example of a one-pot synthesis of a donor-acceptor diblock copolymer. The methods of synthesis are described, and characterization of the block copolymers is reported.
35
Bond, Steven Winfred. "Through-silicon circuit optical communications links." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/15390.
Full text
36
Shen, Jeng-Jung. "Heterogeneous integration and the exploitation of strain in MBE growth : engineered substrates." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/13046.
Full text
37
Agrawal, Ankur. "Development and characterization of advanced electron beam resists." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/34054.
Full text
38
Tang, Wei 1976. "High-speed parallel optical receivers." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103298.
Full textAbstract:
Parallel optical interconnects (POI) have attracted a great deal of attention in the past two decades as the system bandwidth continues to increase. Optical interconnects are known to have more advantages than their electrical counterparts in many aspects such as crosstalk, bandwidth distance product, power consumption, and RC time delay. The parallelization of several optical links is also an effective method to increase the aggregate data rate while keeping the component count manageable and to reduce the unit cost of optics, electronics, and packaging at lower line rate.Parallel optical transceiver modules running at several gigabits per second are commercially available nowadays. Parallel optical receivers are one of the key components of parallel interconnected systems. In this work, we describe how a low-power parallel CMOS preamplifier IC and a deskew IC have been designed and fabricated through the IBM 0.13mum CMOS technology. The performances of three different transimpedance amplifier (TIA) topologies are compared experimentally. The best of the three TIAs shows a differential gain of 56.2dBO, 2.6GHz bandwidth, and less than -16dBm sensitivity with a bit-error-rate (BER) less than 10-12. The TIA consumes 2.5mW of power from a 1.2V supply while the channel power is 22mW with a 400mV pp differential output swing.
A novel method of accurately measuring the crosstalk power penalty with an on-chip PRBS generator is proposed and its implementation is described. The use of an on-chip PRBS generator to drive the dummy channels eliminates the data pattern dependence between the aggressors and the victim. The inevitable channel skew associated with parallel channels can be removed by a phase-locked loop (PLL) based deskew method. We investigated the skew compensation range of this method theoretically and our experimental results confirm our conclusion.
Various practical design and test techniques such as photodiode modeling, AC coupling, low-pass filtering and continuous skew generation, and their implementations, are discussed and implemented in this thesis.
39
Leung, Yee-pan, and 梁懿斌. "A study on the fabrication and applications of quasi-one-dimensional zinc selenide nanostructures." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39848942.
Full text
40
Bhavnagarwala, Azeez Jenúddin. "Voltage scaling constraints for static CMOS logic and memory cirucits." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/15401.
Full text
41
Teru, Agboola Awolola. "Efficient rectenna circuits for microwave wireless power transmission." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/481.
Full textAbstract:
Miniaturisation has been the holy grail of mobile technology. The ability to move around with our gadgets, especially the ones for communication and entertainment, has been what semiconductor scientists have battled over the past decades. Miniaturisation brings about reduced consumption in power and ease of mobility. However, the main impediment to untethered mobility of our gadgets has been the lack of unlimited power supply. The battery had filled this gap for some time, but due to the increased functionalities of these mobile gadgets, increasing the battery capacity would increase the weight of the device considerably that it would eventually become too heavy to carry around. Moreover, the fact that these batteries need to be recharged means we are still not completely free of power cords. The advent of low powered micro-controllers and sensors has created a huge industry for more powerful devices that consume a lot less power. These devices have encouraged hardware designers to reduce the power consumption of the gadgets. This has encouraged the idea of wireless power transmission on another level. With lots of radio frequency energy all around us, from our cordless phones to the numerous mobile cell sites there has not been a better time to delve more into research on WPT. This study looks at the feasibilities of WPT in small device applications where very low power is consumed to carry out some important functionality. The work done here compared two rectifying circuits’ efficiencies and ways to improve on the overall efficiencies. The results obtained show that the full wave rectifier would be the better option when designing a WPT system as more power can be drawn from the rectenna. The load also had a great role as this determined the amount of power drawn from the circuitry.
42
Ng, Chik-wai, and 吳植偉. "Design techniques of advanced CMOS building blocks for high-performance power management integrated circuits." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B45896926.
Full text
43
Deshpande, Sandeep. "A cost quality model for CMOS IC design." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12042009-020251/.
Full text
44
Whyburn, Gordon Patrick. "A simple organic solar cell." Pomona College, 2007. http://ccdl.libraries.claremont.edu/u?/stc,21.
Full textAbstract:
Finding renewable sources of energy is becoming an increasingly important component of scientific research. Greater competition for existing sources of energy has strained the world’s supply and demand balance and has increased the prices of traditional sources of energy such as oil, coal, and natural gas. The experiment discussed in this paper is designed to identify and build an inexpensive and simple method for creating an effective organic solar cell.
45
Wilson, Jeffrey. "Analysis of power requirements inside of NMOS integrated circuits." Full text open access at:, 1986. http://content.ohsu.edu/u?/etd,134.
Full text
46
Moreno, Debra Ann. "Design, synthesis, and characterization of monomeric group 2 element Bis(alkoxide) compounds ; Part II, Synthesis and characterization of some group 2 element imidophosphonate compounds." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/30267.
Full text
47
Xiao, Haiqiao. "Design of Radio-Frequency Filters and Oscillators in Deep-Submicron CMOS Technology." PDXScholar, 2008. https://pdxscholar.library.pdx.edu/open_access_etds/5233.
Full textAbstract:
Radio-frequency filters and oscillators are widely used in wireless communication and high-speed digital systems, and they are mostly built on passive integrated inductors, which occupy a relative large silicon area. This research attempted to implement filters and oscillators operating at 1-5 GHz using transistors only, to reduce the circuits’ area. The filters and oscillators are designed using active inductors, based on the gyrator principle; they are fabricated in standard digital CMOS technology to be compatible with logic circuits and further lower the cost. To obtain the highest operating frequency, only parasitic capacitors were used.
Two new active-inductor circuits are derived from this research, labeled allNMOS and all-NMOS-II. The all-NMOS active inductor was used to design high-Q bandpass filters and oscillators, which were fabricated in TSMC’s 0.18-µm digital CMOS process. The highest center frequency measured was 5.7 GHz at 0.20-µm gate length and the maximum repeatably measured Q was 665. 2.4-GHz circuits were also designed and fabricated in 0.40-µm gate length. The all-NMOS-II circuit has superior linearity and signal fidelity, which are robust against process and temperature variations, due to its novel structure. It was used in signal drivers and will be fabricated in commercial products.
Small-signal analysis was conducted for each of the active-inductor, filter and oscillator circuits, and the calculated performance matches those from simulations. The noise performance of the active inductor, active-inductor filter and oscillator was also analyzed and the calculated results agree with simulations. The difference between simulation and measured results is about 10% due to modeling and parasitic extraction error.
The all-NMOS active-inductor circuit was granted a US patent. The US patent for all-NMOS-II circuit is pending. This research generated three conference papers and two journal papers.
48
Ntwampe, Seteno Karabo Obed. "Multicapillary membrane bioreactor design." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/897.
Full textAbstract:
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2005The white rot fungus, Phanerochaete chrysosporium, produces enzymes, which are capable of degrading chemical pollutants. It was detennined that this fungus has multiple growth phases. The study provided infonnation that can be used to classify growth kinetic parameters, substrate mass transfer and liquid medium momentum transfer effects in continuous secondary metabolite production studies. P. chrysosporium strain BKMF 1767 (ATCC 24725) was grown at 37 QC in single fibre capillary membrane bioreactors (SFCMBR) made of glass. The SFCMBR systems with working volumes of 20.4 ml and active membrane length of 160 mm were positioned vertically. Dry biofilm density was determined by using a helium pycnometer. Biofilm differentiation was detennined by taking samples for image analysis, using a Scanning Electron Microscope at various phases of the biofilm growth. Substrate consumption was detennined by using relevant test kits to quantify the amount, which was consumed at different times, using a varying amount of spore concentrations. Growth kinetic constants were detennined by using the substrate consumption and the dry biofilm density model. Oxygen mass transfer parameters were determined by using the Clark type oxygen microsensors. Pressure transducers were used to measure the pressure, which was needed to model the liquid medium momentum transfer in the lumen of the polysulphone membranes. An attempt was made to measure the glucose mass transfer across the biofilm, which was made by using a hydrogen peroxide microsensor, but without success.
49
Mony, Madeleine. "Reprogrammable optical phase array." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103276.
Full textAbstract:
The evolving needs of network carriers are changing the design of optical networks. In order to reduce cost, latency, and power consumption, electrical switches are being replaced with optical switching fabrics at the core of the networks. An example of such a network is an Agile All-Photonic Network (AAPN).This thesis presents a novel device that was designed to operate as an optical switch within the context of an AAPN network. The device is a Reprogrammable Optical Phase Array (ROPA), and the design consists of applying multiple electric fields of different magnitudes across an electro-optic material in order to create a diffractive optical element. The configuration of the electric fields can change to modify the properties of the diffractive device.
Such a device has a wide range of potential applications, and two different ROPA designs are presented. Both designs are optimized to function as 1xN optical switches. The switches are wavelength tunable and have switching times on the order of microseconds. The ROPA devices consist of two parts: a bulk electro-optic crystal, and a high-voltage CMOS chip for the electrical control of the device. The design, simulation, fabrication and testing of both the electrical and optical components of the devices are presented.
50
Constantin, Nicolas 1964. "Analysis and design of a gated envelope feedback technique for automatic hardware reconfiguration of RFIC power amplifiers, with full on-chip implementation in gallium arsenide heterojunction bipolar transistor technology." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115666.
Full textAbstract:
In this doctoral dissertation, the author presents the theoretical foundation, the analysis and design of analog and RF circuits, the chip level implementation, and the experimental validation pertaining to a new radio frequency integrated circuit (RFIC) power amplifier (PA) architecture that is intended for wireless portable transceivers.A method called Gated Envelope Feedback is proposed to allow the automatic hardware reconfiguration of a stand-alone RFIC PA in multiple states for power efficiency improvement purposes. The method uses self-operating and fully integrated circuitry comprising RF power detection, switching and sequential logic, and RF envelope feedback in conjunction with a hardware gating function for triggering and activating current reduction mechanisms as a function of the transmitted RF power level. Because of the critical role that RFIC PA components occupy in modern wireless transceivers, and given the major impact that these components have on the overall RF performances and energy consumption in wireless transceivers, very significant benefits stem from the underlying innovations.
The method has been validated through the successful design of a 1.88GHz COMA RFIC PA with automatic hardware reconfiguration capability, using an industry renowned state-of-the-art GaAs HBT semiconductor process developed and owned by Skyworks Solutions, Inc., USA. The circuit techniques that have enabled the successful and full on-chip embodiment of the technique are analyzed in details. The IC implementation is discussed, and experimental results showing significant current reduction upon automatic hardware reconfiguration, gain regulation performances, and compliance with the stringent linearity requirements for COMA transmission demonstrate that the gated envelope feedback method is a viable and promising approach to automatic hardware reconfiguration of RFIC PA's for current reduction purposes. Moreover, in regard to on-chip integration of advanced PA control functions, it is demonstrated that the method is better positioning GaAs HBT technologies, which are known to offer very competitive RF performances but inherently have limited integration capabilities.
Finally, an analytical approach for the evaluation of inter-modulation distortion (IMD) in envelope feedback architectures is introduced, and the proposed design equations and methodology for IMD analysis may prove very helpful for theoretical analyses, for simulation tasks, and for experimental work.