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1	Integrating Optical Emitters into Silicon Photonic Waveguides Milgram, Joel 04 1900 (has links) <p>This thesis reports work targeting the integration of Si light emitters with optical waveguides. Such integrated devices would find utility in a number of applications including telecommunications, optical interconnects, and biological and chemical sensors. Much research has been directed by others on how to improve the emission efficiency and achieve lasing in VLSI (very large scale integration) compatible sources. Here, the focus is on how such devices can be integrated with planar waveguides. Two enhancement techniques were selected for potential integration; defect engineering (DE), and Si nanocrystals (Si-nc) embedded in Si02• Defect engineered light emitting diodes (LEDs) made on silicon-on-insulator (SOI) and emitting at 1.1 μm were successfully demonstrated. In addition, surface photoluminescence from SOI was analyzed to account for interference from the SOI cavity. However, it was determined that the emission efficiency of defect engineered LEDs studied during the course of this work is below that which was reported previously, and that the fabrication procedure thus suffers from irreproducibility. Barring an enormous advancement in the DE technique, it is concluded that the emission efficiency is too small to make use of its integration potential. </p><p>A more successful approach was obtained from the Si-nc system fabricated using electron-cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD). Optically pumped edge emitting devices were designed, fabricated and characterized. The devices are comprised of Si-ncs emitting at 800 nm, integrated with slab silicon nitride waveguides. This work is the first report of edge emission from Si-ncs integrated with silicon nitride waveguides. Edge emission and waveguide properties were characterized in the ~850 nm emission band of the Si-ncs. The edge emission was well described as a propagating mode, attenuated primarily by the Si-nc film. Propagation losses of a typical air/Si-nc/SiNx/Si02 waveguide were measured to be 11 ± 2 dB/cm and 20 ± 2 dB/cm at 850 nm in the TE and TM polarizations respectively. A wavelength dependent loss of -0.14 ± 0.03 dB/(cm*nm) was found to exist in the material loss of Si-nc films. In addition, the Si-nc films were found to undergo a partially recoverable photo-induced degradation of PL efficiency during exposure to pump light. Processing techniques compatible with both high efficiency Si-nc and low loss silicon nitride were developed and described. A two-sectioned photonic device was also designed, fabricated and characterized. The device contained an optically pumped Si-nc emitting waveguide section integrated with a low loss silicon nitride slab waveguide. The potential for optically pumped Si-nc emitters integrated with silicon nitride photonic circuits thus appears promising.</p> / Thesis / Doctor of Philosophy (PhD) Silicon light emitters optical waveguides planar waveguides integration Edge emission photonic circuits
2	A modular synthesis of processable and thermally stable semi-fluorinated aryl ether polymers via step-growth polymerization of fluoroalkenes Shelar, Ketki Eknath 13 May 2022 (has links) Tailored fluoropolymers remain the leading choice for a wide variety of advanced high-performance applications, including electronic/optical and energy conversion, owing to their unique blend of complementary high-performance properties. Amorphous semi-fluorinated polymers exhibit improved solubility and melt processability when compared to traditional perfluoropolymers. A leading class of semi-fluorinated aryl ether polymers includes perfluorocyclobutyl (PFCB), perfluorocycloalkenyl (PFCA), and fluoroarylene vinylene ether (FAVE) polymers. Monomers containing aromatic trifluorovinyl ethers (TFVE) are used to synthesize PFCB polymers via radical-mediated [2+2] cyclodimerization. On the other hand, FAVE and PFCA polymers are polymerized via base-mediated nucleophilic addition/elimination of bisphenols with TFVE monomers and decafluorocyclohexene respectively. The use of different monomer cores (aromatic, aliphatic, contorted, and renewable) should help to develop general structure/property relationships for this versatile and expanding approach to semi-fluorinated aryl ether polymers. The enchainment of polycyclic aromatic hydrocarbon (PAH) cores with functional fluorocarbon groups (or segments) recently afforded a new class of semi- fluorinated polymers in the continuing quest for novel organic materials for potential applications in optoelectronic, gas-separation, and advanced composites. Chapter 2 details the incorporation of commercially available acenaphthenequinone was achieved to afford PFCB aryl ether polymers with excellent solubility, high thermal stability, and film-forming capability. Chapter 3 represents base-promoted nucleophilic addition/elimination of commercial bisphenols with TFVE-triphenylene monomers affording FAVE aryl ether polymers possessing excellent solution processability, high thermal stability and photostability. In addition, triphenylene-enchained FAVE polymers exhibit extreme thermal-oxidative photostability and emit blue light after heating in air at 250 °C for 24 h. Further, time-dependent density functional theory (TD-DFT) computations were performed to understand electronic polymer structures. In one case, post-polymerization Scholl coupling converted the central triphenylene core to afford a hexabenzocoronene containing semi-fluorinated polymer with new optoelectronic properties. Chapter 4 demonstrates synthesis and characterization of renewable semi-fluorinated polymers obtained using aliphatic diol isosorbide. This renewable diol readily polymerizes with bis-TFVE derivatives of bisphenol A and 6F to provide high molecular weight thermoplastics exhibiting excellent solubility and tough, transparent film-forming capability. Finally, Chapter 5 presents synthesis of TFVE enchained corannulene which gave blue-light emission and outstanding processability. Synthesis and characterization, including the new materials' optical, thermal, and electronic properties, is presented. fluoropolymers renewable polymers blue-light emitters corannulene isosorbide triphenylene thermally stable polymers polycyclic aromatic hydrocarbon polymers poly aryl ethers solution and melt-processable polymers processable 2D-NMR of isosorbide Chemistry Materials Chemistry Organic Chemistry Other Materials Science and Engineering Polymer Chemistry Structural Materials
3	Lanthanide Doped Wide Band Gap Semiconductors: Intra-4f Luminescence and Lattice Location Studies / Lanthanid-dotierte Halbleiter mit großer Bandlücke: Intra-4f Lumineszenz- und Gitterplatzuntersuchungen Vetter, Ulrich 15 July 2003 (has links) No description available. Mathematics and Computer Science Lanthanide Kathodoluminesznez intra-4f Elektronenübergänge Europium Thulium Gadolinium Halbleiter mit großer Bandlücke Aluminiumnitrid kubisches Bornitrid Siliziumkarbid Diamant dünne Schichten tetraedrischer amorpher Kohlenstoff Lichtemitter Starkniveau-Spektroskopie Kristallfeldanalyse Kathodolumineszenz Energiematrix Judd-Ofelt-Theorie Ionenimplantation massenselektierte Ionenstrahldeposition Emissionschanneling Gitterplatz Mössbauerspektroskopie radioaktive Lanthanidisotope 530 Physik lanthanides cathodoluminescence intra-4f electron transitions europium thulium gadolinium wide band gap semiconductors aluminum nitride cubic boron nitride silicon carbide diamond thin films tetrahedral amorphous carbon light emitters Stark level spectroscopy crystal field analysis energy matrix Judd-Ofelt theory ion implantation mass-selected ion beam deposition emission channeling lattice location Mössbauer spectroscopy radioactive lanthanide isotopes 33.60 33.30 33.07 33.06 33.43 33.72 RTF 400: Ionenimplantation {Physik} RTG 400: Anregung von Atomen atomare Energiezustände {Atomphysik} RRJ 000: Emissions- Absorptionsspektroskopie {Physik} RVQ 000: Halbleiter {Physik}

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