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1
Rand, Peder. "NanoRisc." Thesis, Norwegian University of Science and Technology, Department of Computer and Information Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9213.
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This report gives a short introduction of the Norwegian wireless electronics company Chipcon AS, and goes on to account for the state of the art of small IP processor cores. It then describes the NanoRisc, a powerful processor developed in this project to replace hardware logic modules in future Chipcon designs. The architecture and a VHDL implementation of the NanoRisc is described and discussed, as well as an assembler and instruction set simulator developed for the NanoRisc. The results of this development work are promising; synthesis shows that the NanoRisc is capable of powerful 16-bit data moving and processing at 50 MHz in an 18nm process while requiring less than 4500 gates. The report concludes that the NanoRisc, and none of the existing IP cores studied, satisfies the requirements for hardware logic replacement in Chipcon transceivers.
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Tan, Bertha. "Nanorod solar cell." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42160.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.Includes bibliographical references (p. 68-70).
The crude oil supply crisis the world is facing today along with the disastrous global warming caused primarily as a result the green house gases, has heightened the need for an eco-friendly and renewable energy technology. Solar cells, with their ability to convert the free and gigantic energy supply of the sun into electricity, are one such attractive choice. In this thesis, a study of the use of new technologies for enhanced solar cell performance based on conversion efficiency is carried out by first understanding the mechanism of selected major solar cell types, followed by an analysis of external or internal factors that affect their performance. One new technology under investigation to boost solar cell efficiency is the introduction of nanorod/wire structures into existing designs. This report discusses this approach in detail, highlighting beneficial characteristics offered and also looking into the structure realization through advanced nanostructure processing techniques. Finally, having a complete technology background at hand, various potential markets for new solar cell technologies are examined.
by Bertha Tan.
M.Eng.
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Friedrich, Wiebke [Verfasser], and Horst [Akademischer Betreuer] Weller. "Semiconductor Nanorods in the Vicinity of Ordered Gold Nanorods / Wiebke Friedrich. Betreuer: Horst Weller." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2015. http://d-nb.info/1073248232/34.
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Lee, Ming-Tao. "Plasmonic Enhanced Fluorescence using Gold Nanorods." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57680.
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The aims of this study are to first immobilize positively charged gold nanorods to negatively charged cell culture surfaces. Second, to use polyelectrolytes for controlling the distance between gold nanorods and fluorophores. This is used to optimally determine the distance, of which maximum fluorescence enhancement is achieved, between gold nanorods and fluorophores. In order to approach these aims, we use UV/VIS absorption spectroscopy, fluorescence spectroscopy, atomic force microscopy, and ellipsometry. The results show that we could control the immobilization of gold nanorods on plastic microwell plates and create reproducible polyelectrolyte layers, in order to control the distance between the gold nanorods and fluorophores. In addition, the localized surface plasmon resonance wavelength red shifted as the PELs increased. In conclusion, we found that the maximum fluorescence enhancement of the fluorophores (Cy7) is about 2.3 times at a fluorophores-nanoparticles separation of approximately 9-12 nm. This work contributes some research information towards the design of optical biochip platforms based on plasmon-enhanced fluorescence.
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Jalali, Nimra. "ZnO nanorods-based piezoelectric energy harvesters." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8948.
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Piezoelectric nanostructures of ZnO were employed for development of vibration energy harvesters. Columnar nanorod structures of ZnO, incorporated into various heterojunction-based device prototypes, were strained to generate voltage signals. The fabricated devices’ prototypes were based on different top electrodes such as: p-n junction-type Poly(3,4-ethylenedioxythiophene) Polystyrene sulfonate (PEDOT:PSS)/ZnO devices, metal-insulator-semiconductor type Poly(methyl methacrylate) (PMMA)/ZnO devices. Similarly, various bottom electrode materials based prototypes were also assembled: ZnO/indium tin oxide (ITO), ZnO/silver (Ag) and ZnO/zinc (Zn). The overall device design was based on flexible electrodes and substrates, due to which low temperature (below 100 °C) fabrication processes were implemented. Device performance measurement and characterisation techniques were explored and implemented to improve the reliability of results. These techniques included open-circuit voltage and short-circuit current output measurement, resistive load matching and impedance analysis. The analysed performance of energy harvester was assessed in relation to its constituent material properties. The parameters which affect the energy harvester performance were investigated and for this p-n junction-based (PEDOT:PSS/ZnO) devices were used. It was analysed that devices with optimum shunt (Rsh) and series resistance (Rs), which were in the ranges of 0.08 – 0.17 kΩ and 0.5 – 1.65 kΩ respectively, generated the highest peak open-circuit voltage (Voc) and peak power density (PL) of 90 – 225 mV and 36 – 54 μW cm-2. However, the p-n junction-based devices with low shunt resistance (Rsh), ranged between 0.2 – 0.3 kΩ, were considered to be affected with leakage losses, such as short-circuits. Therefore, these devices generated lower Voc and PL in the range of 20 - 60 mV and 2 - 16 μW cm-2. Similarly, the p-n junction-based devices with higher Rs, ranged between 0.3 – 0.6 kΩ, were adversely affected by I2R losses and therefore their generated power density was also dropped to 0.22 - 0.25 μW cm-2. In addition to parasitic resistance losses, the most significant phenomenon investigated in ZnO energy harvesters was, screening of polarisation ii charges in ZnO. The polarisation screening effects were observed to be related to the electrical properties of device components like electrode material type and conductivity of ZnO. Hence, the effect of electrode electrical properties on electric field screening was investigated. In this regard, device electrodes were varied and their effect on energy harvesting efficiency was studied. A comparison based on the performance of bottom electrodes like indium tin oxide (ITO), silver (Ag) and zinc foil on device performance was made. It was observed that due to lower screening effects of ITO, the ITO-based devices generated voltage output which was two orders of magnitude higher than the zinc foil-based devices. Similarly, the screening effects of top electrode materials, like PEDOT:PSS and PMMA, on device output generation were investigated. The PMMA-based devices generated average 135 mV which was higher than average 100 mV generation of PEDOT:PSS-based devices; which indicated that the PMMA-based devices had slower screening rate. On the contrary, the PMMA-based devices’ 7 times higher series resistance than PEDOT:PSS-based devices caused the PL of PMMA-based devices to be 0.4 μW cm-2, which was two orders of magnitude lower than 54 μW cm-2 generated by PEDOT:PSS-based devices. Further to electrode materials study, polarisation screening caused by electrical properties of ZnO was also anaylsed. In this regard, the surface-induced conductivity of ZnO was decreased by using surface coating of copper thiocyanate (CuSCN). The reduction in ZnO conductivity was considered to reduce the screening of polarisation charges. Consequently, the power density of ZnO devices was enhanced from 54 μW cm-2 to 434 μW cm-2.
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Vukicevic, Uros. "TiO2 nanorod polymer composite materials." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/7669.
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The remarkable characteristics of Ti02 are widely used, from everyday life applications (pigments, food/cosmetics additives) to more specialised systems, including photovoltaics and structural composites. Use in polymers is substantial (25% of all Ti02 produced), but most applications and research focus on commercial powders. A new generation of Ti02 nanoparticles has emerged, based on very small, single-crystals, with well-defined morphology and phase. A limited number of papers report the use of this new nanoscale Ti02 in polymer nanocomposites, and indicate improved properties. Although the synthesis of anisotropic nanoparticles (e. g. nanorods) has been well-reported, use in polymer nanocomposites remains largely unreported. This thesis broadly covers three topics: (1) synthesis of Ti02 nanorods using different sol-gel routes in presence of structure directing agents, (2) modification of the nanorod surface chemistry in order to control dispersion and surface properties and (3) fabrication of titania nanorod-polymer composites. Singlecrystal anatase nanorods were produced with variable aspect ratio (3-12), depending on the specific structure directing agent (SDA) used during synthesis. Due to organic functionalisation at the nanorod surface, nanorods could be well dispersed in chloroform. A new procedure, based on the self-cleaning ability of Ti02 under UV, was developed for removal of organics from the nanorod surface, without compromising the nanorod morphology, crystallinity or dispersibility. This powerful tool can be used to change the surface character of the nanorods to generate aqueous TNR dispersions. Stable dispersions were achieved using quaternary ammonium hydroxides to modify the surface electrostatically and sterically. Once dispersed individually, the surface can be further modified by sol-gel chemistry. Composite work involved blending both organic and water-soluble polymers with nanorod dispersions in chloroform and water, respectively, to produce composite films of exceptional optical transparency, even for nanorod loadings up to 30 wt%. The films possess very strong, wavelength-tuneable UV absorbance, which could be used in UV filters and optical limiting. The presence of SDAs or dispersants at the nanorodpolymer interface hinders strong adhesion, as evidenced by marginally lower tensile strength and thermal stability of the nanocomposites. The photo-stability of the nanorod composites is comparable to that of the pure polymer and better than that of composites with commercial equiaxed TiO2 nanoparticles.
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Garcia, Marisol. "TRULY NON INVASIVE GLUCOSE OPTICAL SENSOR BASED ON METAL NANOPARTICLES GENERATION." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2260.
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Diabetes is a disease that causes many complications in human normal function. This disease represents the sixth-leading cause of death in USA. Prevention of diabetes-related complications can be accomplished through tight control of glucose levels in blood. In the last decades many different glucose sensors have been developed, however, none of them are really non invasive. Herein, we present the study of the application of gold and silver nanoparticles with different shapes and aspect ratios to detect glucose traces in human fluids such as tears and sweat. This is to our knowledge the first truly non invasive glucose optical sensor, with extraordinary limit of detection and selectivity. The best proven nanoparticles for this application were gold nanospheres. Gold nanospheres were synthesized using chloroauric acid tri-hydrated (HAuCl4.3H2O) in solution, in the presence of glucose and ammonia hydroxide. The higher the glucose concentration, the higher the number of nanoparticles generated, thus the higher the extinction efficiency of the solution. The linear dependence of the extinction efficiency of the gold nanoparticles solution with glucose concentration makes of this new sensor suitable for direct applications in biomedical sensing. Our approach is based on the well known Tollens test.M.S.
Department of Chemistry
Arts and Sciences
Industrial Chemistry
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Murali, Shanthi Davis Virginia A. "Coupled self-assembly and flow alignment of silver nanorods." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/FALL/Chemical_Engineering/Thesis/Murali_Shanthi_47.pdf.
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Subedi, Kamal. "Synthesis and Characterization of PbS Nano Sheets." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1403097151.
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Kandel, Shreedhar R. "Control of Shape Change of PbSe Nano Structure by Chloroalkane." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1435056285.
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Rihtnesberg, David Boban. "Investigation of ZnO nanorods for UV detection." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-46704.
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In recent years, there has been increasing interest in ZnO semiconductors for optoelectronic application in the UV wavelength region due to its large exciton binding energy of 60 meV and wide bandgap energy of 3,37 eV at room temperature. One-dimensional ZnO nanostructures such as nanorods or nanowires have been considered as promising candidates for UV sensing and detecting applications owing to its high surface to volume ratio. In this thesis work 5 different types of UV photodetectors based on ZnO nanorods were fabricated successfully. The basic technique is to utilize a chemical solution synthesis method for forming ZnO nanorods on different types of substrate, and then fabricate simple metal semiconductor metal (MSM) and P-doped/N- doped (PN) photodetectors using the nanorods as UV detecting material. The MSM photodetectors are accomplished using interdigitated electrodes forming by the thin gold fingers on the desired substrates, while the PN photodetector were fabricated using ZnO nanorods sandwiched between a top metal contact and a heavy P-doped Si substrate. So far various lateral and vertical ZnO nanorods/nanowires with different dimensions (60 nm to 80 nm in diameter) and length (1 μm to 7 μm) have been synthesized. Also, the ZnO nanoflower (about 5 μm in height) arrays based on ZnO nanorods were demonstrated. The nanoflowers were mainly formed by three process steps. First a seed layer was spin coated on Si substrate, and then a positive photoresist layer with thickness of 1.5 μm was patterned for allowing the growth of ZnO nanorods precisely in desired locations. Finally the photoresist was stripped away. The structural and composition properties of the ZnO nanostructures (seed, nanorods and nanoflowers) were inspected and characterized by implement of optical microscope, atomic force microscopy (AFM), scanning electron microscope (SEM), x-ray photoelectron spectroscopy (XPS). The device performance was characterized by current-voltage (I-V) characteristics in the dark, visible light and UV light, spectral photoresponse and time response as UV light switching on and off. Demonstration of cost-effective ZnO nanorods UV photodetectors through this work reveals a promising potential for extending nano- and micro-technologies beyond the lab bench for future commercialization of such components, thus facilitate entry to new markets.
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Thomas, Michael. "Liquid crystal induced ordering of gold nanorods." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633257.
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The main themes of this work cover the preparation, suspension and analysis of functionalised gold nanorods in small molecule nematic liquid crystal solvents as archetypal systems to further the understanding of anisotropic nanoparticle suspensions in anisotropic molecular solvents. The analysis has focussed on the stability of these suspensions towards aggregation and sedimentation as well as their response to electric fields of varying strength and frequency, monitored by Synchrotron Radiation Small Angle X-ray Scattering. The influence of surface functionalities (including short n-alkylthiol monolayers, functionalised silica encapsulation and polar and non-polar polymeric brushes) upon nanorod behaviour has been reported. In doing so, it has been demonstrated that when thin steric layers are employed, nanorods form well-ordered, assembled nanostructures that display excellent orientational ordering upon inclusion in small molecule nematics under the influence of an electric field. If the steric layer is sufficiently thick, the interparticle van der Waals attractive forces can be mediated yielding highly stable dispersed gold nanorods in non-aqueous isotropic solvents. The stability of these nanorod 'inclusions in the nematic phase has been shown to be strongly influenced by both the thickness and the chemical composition of the steric layer. The orientational response of individually dispersed nanorods (modified with polar, covalently ' bound polyethylene glycol brush layers) has been shown to be influenced by aspect ratio and polymer length. Their response to flow and magnetic fields, as well as simulations of the effect of anisotropic dielectric solvents on particle alignment in electric fields, have been used to develop an understanding of the strong orientational response these suspensions. In addition, nanorod fractions that were not freely-dispersed have been characterised, providing insight into the design of future materials that can utilise the extensive understanding developed from these diversely modified nanorod archetypes.
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Hsu, Yuk-fan, and 許玉芬. "Zinc oxide nanorods and tetrapods: propertiesand applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40687600.
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Ng, Man-ching Alan, and 吳文政. "Light emitting diodes based on ZnO nanorods." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B43572005.
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Ng, Man-ching Alan. "Light emitting diodes based on ZnO nanorods." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43572005.
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De, Puig Guixé Helena. "Control of blood clotting using gold nanorods." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81734.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
We have developed a method to externally control blood clotting using gold nanoparticles. Gold nanorods (NRs) have unique size and shape-dependent optical properties that can be used for externally controlled release of biomolecules by laser excitation. Femtosecond pulsed laser irradiation at the NR longitudinal surface plasmon resonance peak (LSPR) can excite the NRs and induce melting, and thus cause release of drug or biomolecular payload on the NR. Because the peak wavelength of the LSPR changes with NR aspect ratio, NRs with different aspect ratios can be independently excited at different wavelengths to release different payloads in a mutually exclusive fashion. This approach can be used to create a biological switch for blood clotting by releasing a single stranded (ssDNA) thrombin binding aptamer (TBA) upon laser irradiation. It is possible to control blood clotting by releasing TBA that binds and inhibits thrombin, and an antidote consisting of a complementary ssDNA sequence that binds to TBA and restores thrombin activity. Both the TBA and the antidote are loaded onto NRs with different aspect ratios. This enables us to use laser excitation at one wavelength to deliver the TBA and inhibit thrombin and consequently blood clotting. We then use a different wavelength to deliver the antidote and reverse the effect of the TBA. We use covalent attachment techniques (thiol-gold binding) for loading the ssDNA on the NRs and study the interface between the NRs and the biomolecules. We also take advantage of serum protein coronas for loading, which enable enhanced loading capacities. This localized, selective and externally controlled release of biomolecules represents an advance that could impact a number of biological applications, where the current practice is systemically administering drugs though the whole bloodstream and relying on physiological clearance to restore the system.
by Helena de Puig Guixé.
S.M.
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Chiluwal, Shailendra. "Understanding The Growth Mechanism Of PbSe Nanorods." Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1466432317.
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Ghopry, Samar A. "Magnetic Properties of Hematite (α-Fe2O3) Nanorods." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3662.
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At this study three samples of hematite nanorods were deposited on the silicon substrates with different varieties of glancing angle deposition techniques. One sample (S1) was prepared by using thermal deposition with partially ionized beam (PIB) and substrate rotation. The second sample (S2) was synthesized by using thermal deposition with PIB and no substrate rotation. The third sample (S3) was obtained by using E-beam deposition, PIB and rotating substrate. In addition, one sample of magnetite nanorods (S4) has been prepared in order to compare the magnetic properties of the two different iron oxides. S4 was prepared by using thermal deposition and fixed glancing angle deposition, but no PIB was applied. The hysteresis loop has been studied for all samples and the temperature dependent magnetic properties of one of the hematite samples and the magnetite been studied, too. The studies of the magnetic hysteresis for S1, S2, S3 and S4 showed that all of the samples have hysteresis loops but with dissimilar values of the saturation magnetization Ms, remanence MR, and coercivity HC. Furthermore, the hysteresis loops of all four samples showed different behaviors as the nanorods of the samples change the orientation with respect to the magnetic field. In addition to that fact, the hysteresis loop demonstrated that samples that have similar morphology have like behavior of the hysteresis loop. Also, it has found that S2 has the largest hysteresis loop of all hematite samples and it has large hysteresis loop in the perpendicular and parallel directions with the field as well. However, the magnetite hysteresis loops are significant larger than the ones of the hematite. Likewise, the studies of the temperature dependence magnetic properties of S2 and S4 showed that the ZFC and FC M-T curves of S1and S4 behaved differently when the direction of the nanorods changed from perpendicular to parallel with the field. In addition, the ZFC and FC M-T curves of hematite were different than the ZFC and FC M-T curves of magnetite.
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Auer, Mathias. "Preferentially Orienting Ag Nanoparticles Using CaF2 Nanorods." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2730.
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A study was done to examine the effect of surface orientation as well as heterogeneous epitaxy at an interface between two materials with a large lattice mismatch. Silver nanoparticles of different diameters were grown in an effort to study methods of preferentially orienting the geometry of metal nanoparticles. Arrays of calcium fluoride nanorods were grown on silicon substrates using oblique angle thermal vapor deposition. The chamber operated at an ultra high vacuum pressure of 10^-10 Torr during the deposition of the rods and an oblique angle of 75° was kept between the silicon substrate normal and the direction of incident flux. A method was then developed to grow silver nanoparticles exclusively on the (111) facet of the calcium fluoride tips. This was accomplished by once again using oblique angle deposition with an angle of 75° along with the larger size of the (111) calcium fluoride tip facet. Cross sectional scanning electron microscopy and transmission electron microscopy imaging was used to verify that the nanoparticles adhered exclusively to the desired facet of the tip. Using selected area diffraction, (SAED) and dark field in the TEM, it was shown that the nanoparticles did grow at a (111) orientation at the interface between them and the calcium fluoride rods. Different thicknesses and diameters of nanoparticles were then grown to determine what an ideal size was to achieve the most (111) orientation of the nanoparticles. Thicknesses of the particles varied between 5 nanometers and 15 nanometers. Through characterization it was shown that all three of the different thicknesses grown exhibited (111) orientation of the silver nanoparticles, both at the interface and in the overall nanoparticle as well with the 10 nanometer sample being the most ideal in terms of the desired result. Lattice straining of the silver nanoparticles was also observed by characterization through diffraction and SAED.
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Mbulanga, Crispin Munyelele. "Defect-related photoluminescence of zinc oxide nanorods." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/10318.
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In this dissertation, Zinc oxide (ZnO) nanorods grown by a two-step chemical bath deposition method on Si substrate is characterized. Research was conducted on ZnO nanorods for the understanding of their optical properties at room temperature (RT), with the emphasis on the visible luminescence. To this end, controlled thermal treatments of as-grown ZnO nanorods were conducted under different conditions, such as annealing time and environment, at atmospheric pressure. Results related to the following studies are reported: an investigation of the structure of ZnO nanorods, an analysis of the chemical composition of the surface, an investigation of the surface stoichiometry of the rods, and a study of defect-related photoluminescence of ZnO nanorods upon thermal treatment in different ambients.To achieve this, the samples were investigated by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and room temperature (RT) photoluminescence Spectroscopy (PL). As-grown ZnO nanorods exhibit a hexagonal shape and have the wurtzite structure; they have, respectively, an average length and diameter of ~900 nm and ~50 nm, and most of the rods are perpendicular to the substrate. The main extrinsic species found in as-grown nanostructures are C, H, F, S, and Cl. ToF-SIMS and XPS confirmed the presence of H related-defects, and the oxygen 1 S XPS peak at 531.5 eV is therefore assigned to oxygen bound to H-related defects. Based on stoichiometry studies, it is found that the near surface regions of as-grown ZnO nanorods (2 to 10 monolayers) are rich in Zn. The RT luminescence of as-grown ZnO nanorods exhibits a near band edge emission centered at ~379.5 nm and deep level emission extending from ~450 nm to ~850 nm. When these nanorods are thermally treated at high temperatures (>850 oC), it is found that even though their crystalline quality is preserved, their morphology is significantly affected, regardless of annealing ambient. Furthermore, in the near surface regions of annealed ZnO nanorods it is found that the Zn/O stoichiometric ratios deviate from unity. Specifically, oxygen vacancies form within the first 100 nm from the sample surface. Further from the surface, the material is deficient in Zn. It is deduced from XPS and AES that the ambient affects the activation rate of intrinsic defects. Furthermore, the only extrinsic defects that are affected by thermal treatment are found to be H-related defects. At high annealing temperatures (300 oC to ~700 oC), H-related defects are removed, and this removal process is found to affect significantly the RT luminescence properties of ZnO nanorods. Specifically, hydrogen passivates vacancy-related defects, depending on the thermal treatment. PL spectroscopy is used to follow this passivation effect as a function of annealing temperature, which causes an initial quenching followed by an enhancement of the green and the red luminescence, regardless of the ambient. Finally, the green luminescence that arises following annealing above ~800 oC is assigned to Zn vacancy-related defects, while the red luminescence that dominates the visible band of ZnO nanorods upon annealing between 400 oC and 600 oC is suggested to be due to oxygen vacancy-related defects.
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Dobson, Stephen Robert. "Development of polymer templates for ZnO nanorods." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/d1020805.
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One of the biggest challenges for the semiconductor industry is the development of nanofabrication techniques that allow for the fabrication of structures on a scale tens of nanometers in size. This provides greater potential functionality at reduced costs. Established conventional techniques, such as photolithography, are unable to achieve features below 30 nm due to the inherent limitations of the wavelength of light sources currently available. For this reason block copolymers received considerable attention in order to overcome these challenges in lithographic technology. Block copolymers have an inherent processing advantage of self assembling into various nanoscopic structures such as spheres, cylinders and lamellae amongst others on a scale below 50 nm. The dimensions and structures are readily tuneable based on molecular weights (Mw) and compositions of the copolymers. However, to be usable within industry a great deal more research still needs to be conducted on the use and nature of block copolymers. In this study the block copolymer of poly(styrene-block-methylmethacrylate) (PS-b-PMMA) was investigated as a potential nano-mask for semiconductor growth. Research was conducted on thin films of PS-b-PMMA by altering the parameters influencing the kinetics and thermodynamic effects on the thin films, in order to produce a structure of cylinders of PMMA perpendicular to the substrate within a PS matrix on a silicon (Si) substrate. It is shown that thermally annealing the PS-b-PMMA thin films under conditions where there is no preferential interaction of the substrate or open surface with either components of the block copolymer (i.e. PS or PMMA with Si or ambient) and at an appropriate thin film thickness, perpendicular cylinders of PMMA within a PS matrix form in the thin films. The determined ideal thin film thickness is 32 nm, with non-preferential interaction attained between block and substrate by coating a poly(styrene-random-methylmethacrylate) (PS-r-PMMA) on the Si substrate and annealing within a vacuum. Additionally, acetic acid, as a known selective solvent of PMMA, is used to further process the thin film of PS-b-PMMA. Thus a final PS nano-mask containing pores with a diameter tens of nanometers in size is produced. The pores are shown to have an average diameter of 13.5 nm. Measurements were taken throughout the investigation using a scanning probe microscope (SPM) to determine surface topography and phase morphology of the PS-b-PMMA thin films. X-ray reflectometry (XRR) is used to measure film thickness. The research in this study shows that thin films of PS containing hexagonally arranged pores can be produced and could find potential use as a nano-mask for semiconductor growth.
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Alrashid, Ebtihaj Jr. "Premelting Study of Nickel Nanorod Arrays." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3037.
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In this study, samples of nanoscale structures of nickel (Ni) nanorods were prepared using the glancing angle deposition (GLAD) technique. Annealing was done using a split- top tube furnace at high vacuum chamber pressure. The pre-melting of the nanorods was maintained at 500 °C for 30 minutes in all the samples. Using the samples with 90 minutes of GLAD time, the annealing behavior of the nanorods was studied at 300 °C, 400 °C, 500 °C and 600 °C. The nanorods were then imaged using scanning electron microscopy. Using X-ray diffraction, the crystalline microstructures of the nanorods were studied. It was found that with increasing annealing temperatures, the intensity of peaks for both Ni (111) and Ni (200) increased, which indicates that better crystals were formed. The results indicate that re-crystallization occurs after annealing, leading to the formation of larger grain sizes compared to as-deposited grain sizes. Annealing substantially changed the structure of the nanorods, leading to different smoother, more connected crystal structures for the annealed nanorods compared to as-deposited ones.
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Peruch, Silvia. "Ultrafast properties of plasmonic nanorod metamaterial." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/ultrafast-properties-of-plasmonic-nanorod-metamaterial(d981b5e4-b959-4193-8cf1-219b68de08d6).html.
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Plasmonic metamaterials have customized linear and nonlinear optical properties. This thesis investigates the properties of an anisotropic plasmonic metamaterial, consisting of aligned, interacting gold nanorods, to perform ultrafast light modulation, exploiting the intrinsic Kerr nonlinearity of gold. This e ect is based on an illumination-intensity-dependent change in the gold's permittivity, which takes place on ultrafast timescales and induces the intensity-dependent change of the metamaterial's re ection and transmission. A comprehensive theoretical and numerical analysis of the linear and nonlinear response of various con gurations of the metamaterial is performed and compared to experimental results. A new family of hyperbolic waveguided modes above the e ective plasma frequency, enabled by spatial dispersion, is identi ed. The strong nonlinear response and the dynamic modulation capabilities associated with the excitation of the waveguided modes is investigated. The presence of strong electron temperature gradients in the nanorods induced by a control light is shown to determine a stronger nonlinear modulation and to in uence the dynamic response, leading to subpicosecond time recovery components of the nonlinearity. Weak and strong coupling between molecular excitons and the metamaterial's modes can be achieved using core-shell nanorod geometries. The coherent interaction of molecular J-aggregates with coreshell nanorod arrays is analyzed in both the weak and strong coupling regimes. Subpicosecond components of the modulation are determined in the strong coupling conditions. The design of the optical response of the gold nanorod and core-shell metamaterials is studied through the near- to mid- Infrared, key spectral regions for molecular ngerprinting in chemical sensing and absorption spectroscopy. The applicability limits of the analytic approaches using the quasi-static and e ective medium approximations is tested. The results show great potential of the plasmonic nanorod metamaterial for ultrafast nonlinear optics in free-space and integrated applications, in a broad spectral range.
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Tam, Kai-hang. "Zinc oxide nanorods hydrothermal growth, properties and applications /." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557340.
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Almeida, Trevor P. "Hydrothermal synthesis and characterisation of α-Fe2O3 nanorods." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11685/.
Full textAbstract:
The hydrothermal synthesis (HS) of α-Fe2O3 nanorods (NRs) is investigated using a combination of complementary analytical techniques. The construction of an HS ‘process map’ as a function of temperature, time and phosphate (PO43-) concentration provides insight into the nature of intermediate β-FeOOH NR precipitation, dissolution and subsequent α-Fe2O3 growth, along with the effect of PO43- anion concentration on the development of α-Fe2O3 particle shape. An HS processing temperature of 200˚C and an Fe3+ : PO43- molar ratio of 31.5 yielded crystalline acicular α-Fe2O3 NRs with an aspect ratio of ~ 7 (~ 420 nm long, ~ 60 nm wide). The additional effects of FeCl3 concentration, pH, stage of phosphate addition and α-Fe2O3 seed content on the growth of α-Fe2O3 NRs is investigated. The development of a novel valve-assisted pressure autoclave is described, facilitating the rapid quenching of hydrothermal suspensions into liquid nitrogen, providing ‘snapshots’ closely representative of the in situ physical state of the synthesis reaction products. Examination of the samples acquired as a function of reaction time and known reaction temperature provides fundamental insight into the anisotropic crystal growth mechanism of the acicular α-Fe2O3 NRs. It is considered that the release of Fe3+ ions back into solution through intermediate β-FeOOH dissolution supplies the nucleation and growth of primary α-Fe2O3 nanoparticles (NPs) (< 10 nm) which subsequently coalescence through a mechanism of oriented attachment (OA) with increasing temperature, into larger, acicular α-Fe2O3 NRs. Fourier transform infra-red spectroscopy investigation of the quenched reaction products provides evidence for PO43- absorption on the α-Fe2O3 NPs, in the form of mono or bi-dentate (bridging) surface complexes, on surfaces normal and parallel to the crystallographic α-Fe2O3 c-axis, respectively. The balance between bi-dentate and mono-dentate phosphate absorption is considered to be critical in mediating the acicular shape of the α-Fe2O3 NRs. A feasibility study on the incorporation of ferromagnetic cobalt, Co3O¬4 NPs or CoFe2O4 NPs into α-Fe2O3 NRs during HS is presented. In all cases, there is no evidence for the incorporation of cobalt within the α-Fe2O3 NRs or the formation of hetero-nanostructures with the Co3O4 or CoFe2O4 NPs. The overall growth mechanism of single crystalline acicular α-Fe2O3 NRs involves the anisotropic growth and dissolution of intermediate β-FeOOH NRs, governed by its crystallographic structure, and the OA of primary α-Fe2O3 NPs, mediated by the preferential absorption of phosphate surfactant.
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Tam, Kai-hang, and 譚啟鏗. "Zinc oxide nanorods: hydrothermal growth, properties and applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557340.
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Asif, Muhammad. "Electrochemical Biosensors Based on Functionalized Zinc Oxide Nanorods." Licentiate thesis, Norrköping : Department of Science and Technology, Linköping University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-19573.
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Hsu, Yuk-fan. "Zinc oxide nanorods and tetrapods properties and applications /." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40687600.
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Wang, Tianyi 1982. "Development and application of optical imaging techniques in diagnosing cardiovascular disease." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5215.
Full textAbstract:
Atherosclerosis and specifically rupture of vulnerable plaques account for 23% of all deaths worldwide, far surpassing both infectious diseases and cancer. Plaque-based macrophages, often associated with lipid deposits, contribute to atherogenesis from initiation through progression, plaque rupture and ultimately, thrombosis. Therefore, the macrophage is an important early cellular marker related to vulnerability of atherosclerotic plaques. The objective of my research is to assess the ability of multiple optical imaging modalities to detect, and further characterize the distribution of macrophages (having taken up plasmonic gold nanoparticles as a contrast agent) and lipid deposits in atherosclerotic plaques.
Tissue phantoms and macrophage cell cultures were used to investigate the capability of nanorose as an imaging contrast agent to target macrophages. Ex vivo aorta segments from a rabbit model of atherosclerosis after intravenous nanorose injection were imaged by optical coherence tomography (OCT), photothermal imaging (PTW) and two-photon luminescence microscopy (TPLM), respectively. OCT images depicted detailed surface structure of atherosclerotic plaques. PTW images identified nanorose-loaded macrophages (confirmed by co-registration of a TPLM image and corresponding RAM-11 stain on a histological section) associated with lipid deposits at multiple depths. TPLM images showed three-dimensional distribution of nanorose-loaded macrophages with a high spatial resolution. Imaging results suggest that superficial nanorose-loaded macrophages are distributed at shoulders on the upstream side of atherosclerotic plaques at the edges of lipid deposits. Combination of OCT with PTW or TPLM can simultaneously reveal plaque structure and composition, permitting assessment of plaque vulnerability during cardiovascular interventions.text
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Wang, Ying-Jhe, and 王英哲. "Mechanism and Properties of Selective-grown ZnO Nanorods on Periodic Si Nanorod Arrays." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/z4g377.
Full textAbstract:
碩士國立中正大學
光機電整合工程研究所
102
Periodic Si nanorod (NR) arrays were fabricated by nanosphere lithography as described in the previous work.1 Self-assembled monolayer of PS sphere was first prepared on Si substrate. Subsequently, plasma etcher was used to reduce the diameter of the PS sphere. Si NRs arrays were etched obtained by metal-assisted chemical etching method, using mixed HF and H2O2 solution. The lengths of Si NRs can be controlled from few to tens micrometer by different etching times. The periodic Si NR arrays exhibit the hydrophobic property, which are used to selectively deposit the ZnO seeds on the top of the Si NRs by dropping the Zn(NO3)2 solution on Si NR arrays. Then, n-ZnO NRs/p-Si NR arrays heterostructure was achieved by the hydrothermal growth of ZnO NRs on the top of seeded Si NRs, the results showed the ZnO NRs grown uniformly on the Si NRs. The proposed nano-heterostructures have advantages in low equipment requirements, low material waste and mass production. Compared to n-ZnO NRs/p-Si substrate heterostructures, the electrical characteristics and photorespones exhibit lower current leakage and higher sensitivity to UV light, respectively.
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Lo, Wen-Fu, and 羅文甫. "Synthesis and characterization of gold nanorods and Au/CdSe core-shell nanorods." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/18559184039700376608.
Full textAbstract:
碩士國立清華大學
化學工程學系
99
Abstract In this study,we use the silver-assisted method to synthesis gold nanorods and control the aspect ratio. Under this kind of seed-mediated growth, we can tune the aspect ratio from 1.8 to 5. Among those gold nanorods we synethsis, we choose gold nanorods with longitudinal surface resonance wavelength between 750nm to 800nm as the seed for synthesizing Au-CdSe core-shell nanorods.In order to adapt cation exchange process, we have to control three major steps：(1)Au-Ag core-shell nanorods synthesis (2) Au-Ag2Se core-shell nanorods synthesis (3) Au-CdSe core-shell nanorods synthesis. In step (1), To get well coverage of Ag shell, we choose PVP and C16TAB as the ligand for synthsizing Au-Ag core-shell nanorods. As the result, we can control the shell thickness at about 3 nm for next step synthesis. In step(2), we choose selenourea as the source for producing Ag2Se shell,meanwhile in the expect of maintain the shell structure, we also control the amount of selenourea we use. By characterizing with HR-TEM and XRD, we finally confirm the heterostructure we produce is Au-Ag2Se core-shell nanorod. In last step, we perform the cation exchange process for transforming Ag2Se shell to CdSe, also increasing the CdSe shell thickness.
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Chen, Hung-Ying, and 陳虹穎. "Optical properties of GaN nanorods." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/38460473922214984360.
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博士國立清華大學
物理學系
97
Based on our optical measurements results, we confirm that PAMBE-grown wurtzite GaN nanorods are completely relaxed, strain-free single crystals. The high emission efficiency and excitonic properties of GaN nanorods have been demonstrated. Moreover, vertically aligned GaN nanorod arrays can act as subwavelength low-refractive-index optical media in both transparent and opaque regions. We have also found that the optical confinement effects dominate the linearly polarized properties of GaN nanorods with diameters in the subwavelength regime of 30−90 nm. We believe that the polarized luminescence reported here for GaN can also be found for other semiconductor materials and for other optical measurements, such as electroluminescence and cathodoluminescence. Because of the superior material properties of GaN nanorods in terms of optical transparency, availability of n- and p-type conductivity, and excellent thermal and chemical stabilities, these results could have important implications for nanophotonics and optoelectronics applications.
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Huang, Lan Jung, and 藍榮煌. "Synthesis of Cadmium Selenide Nanorods." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/46680359366466864106.
Full textAbstract:
碩士國立中正大學
化學研究所
88
We have successfully synthesized water-soluble CdSe nanorods in aqueous CTAB micellar solution using oxidation-reduction method and electrolytic reaction technique. In oxidation-reduction method, we have systematically studied the changes of the morphologic changes of the resulting CdSe samples related to the concentration of solubilizate molecules, cyclohexane, acetone, TDAB and sodium chloride. On the basis of the results from absorption spectra and TEM images, we found that adding certain amount of cyclohexane to the micellar solution can result in rod-like morphology of CdSe with mean aspect ratio 3. We synthesized larger nanoparticles of CdSe by adding few amounts of sodium chloride or TDAB to aqueous CTAB micellar solution. In electrolytic reaction system, the synthesized cadmium selenide nanorods with mean aspect ratio 1.44 were reacted from an electrochemical reaction of selenium anion and cadmium cation. In addition, we added hydrochloric acid to synthesize CdSe nanorods with mean aspect ratio 2.59. Electron diffraction patterns of CdSe nanorods showed that the nanorods exhibited a wurtzite structure. The selected-area energy-dispersive X-ray analyses confirmed that CdSe nanorods contained both cadmium and selenium atoms (Cd : Se = 1 : 1).
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Chao, Chih-Yao, and 趙之堯. "Syntheses of Cadmium Sulfide nanorods." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/85224626101130964244.
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碩士國立中正大學
化學研究所
87
Abstract We have successfully synthesized water-soluble CdS nanorods in aqueous CTAB (hexadecyltrimethyl ammounium bromide) micellar solution using sodium sulfide and cadmium chloride as the reactants. The mean aspect ratio (length/diameter) of the nanorods was controlled by varying the experimental conditions such as the concentration of CdCl2, reaction temperature, and amount of solubilizate molecules. The nanorods were characterized using UV-vis absorption spectroscopy and transmission electron microscopy. The absorption spectra suggested that the band edges of the resulting nanorods are shifted to higher energy than that of the bulk CdS crystals. The TEM images show that the CdS nanorods are single crystalline with a wurtzite structure and strength cylindrical shapes. In addition, we have systematically studied the changes of the morphologic changes of the resulting CdS samples related to the concentrations of solubilizate molecules, cyclohexane, acetone, TOAB (tetra-n-octyl ammounium bromide) and silver nitrate. We found that adding different amount of cyclohexane to the micellar solution can result in different morphologies from spherical, rod to square shape. A model will be proposed to explain these morphologic changes.
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Lee, Cheng-Yu, and 李承諭. "Optical Properties of Gold Nanorods." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/70299964995018441684.
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碩士國立臺灣大學
應用力學研究所
98
If a fluorescence molecule is placed in the proximity of gold nanoparticles and impinged by a plane wave, the surface plasmon resonance will be produced. The gold nanoparticles will excite very strong electric field by the surface plasmon resonance effect. The strong excited electric field will cause fluorescence enhancement effect on the fluorescence molecule. This research primarily emphasizes on studying the difference in fluorescence enhancements between different geometric structures of gold nanoparticles. This study is based on Maxwell electromagnetic theory. By using the method of multiple multipole expansion, this study focuses on the electromagnetic fields of three dimensional gold nanorods. Absorption cross section, scattering cross section, extinction cross section, radiative decay rate, nonradiative decay rate, quantum yield, and fluorescence enhancement factor of gold nanorods are then calculated. The structures considered in this thesis include: single gold nanorod (and nano-ellipsoid), aligned gold nanorods (and nano-ellipsoids), nonaligned gold nanorods and Y-shaped gold nanorods. The result shows that when the size and aspect ratio of gold nanorods and gold nano ellipsoids are the same, the efficiency of gold nanorods is better. The fluorescence enhancement factor of aligned gold nanorods is five times the single. The absorption cross section, scattering cross section and extinction cross section of Y-shaped gold nanorods are almost unchanged when the polarization of planewave changes. While in the weakest case, the fluorescence enhancement factor of Y-shaped gold nanorods is still more than one time.
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JIAN, ZHE-AN, and 簡哲安. "Size effect of NdMn2O5 nanorods." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/61476652639253812008.
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碩士中原大學
物理研究所
101
Six pure NdMn2O5 nanorod samples were fabricated by hydrothermal method. The size of six nanorod samples can be identified as 68(36) nm × 31(14) nm、73(35) nm × 32(12) nm、78(30) nm × 33(8) nm、95(36) nm × 40(12) nm、122(48) nm × 54(16) nm、249(46) nm × 142(36) nm. The orientation of all axial directions of all samples is parallel to c axis of the crystal. To labeled samples in short, the axial length are used and named the sample as
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Lai, Kun-Ting, and 賴坤廷. "Flexible photonic crystal nanorods laser." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/03880142803864208694.
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碩士國立交通大學
影像與生醫光電研究所
100
In recent years, the micro-scale photonic crystal structures have been developed for a variety of optical applications. One of the important topics is the compact laser light source in the photonic integrated circuit. Specific wavelengths and operation modes for applications could be achieved by fine-tuning the geometry of the photonic crystal structure. However, the lasing wavelength would hard to be altered once the laser structure was fabricated. On the other hand, the organic/polymer based devices have advantages such as application flexibility and low cost. We combine the features of compactness in photonic crystal and flexibility in flexible materials. In this thesis, a flexible photonic crystal nanorods laser was demonstrated with InGaAsP nanorods on a polydimethylsiloxane (PDMS) substrate. The InGaAsP nanorods content 4 quantum wells which are designed for 1.55 μm communication wavelength. The lasing action was observed around 1550nm which is a band-edge emission at high-symmetry Γ-point of photonic crystals. One of advantages of the flexible laser is the fine-tuning of optical properties by manipulating its geometry. In this work, we observed the lasing wavelength can be controlled by increasing photonic crystal lattice extension. The lasing wavelength was linearly red-shift up to 26.4 nm as the lattice extension percentage increased to 8.88 %. The wavelength tuning rate is approximately 3 nm for 1 % lattice extension. Those geometric fine-tuning properties indicate the flexible photonic crystal laser can be applied as a compact tunable light source in photonic crystal integrated circuits.
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Jhou, Huang-Wei, and 周黃蔚. "Optical characterization of ZnO nanorods." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/6meqg8.
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碩士國立東華大學
材料科學與工程學系
95
The band-edge excitonic transitions of vertical- and lateral-growth ZnO nanorods on sapphire as well as the vertical-growth ZnO nanorods on Si have been characterized using thermoreflectance (TR) and photoluminescence(PL) measurements in the temperature range between 30 and 300 K. The TR spectra of the nanorods with the largely {0001} planes show considerable difference in energy and lineshape with respect to those of the other sample with the largely side planes of {10 0}. The experimental TR result at each temperature clearly indicates the band-edge excitons(A, B, and C) measured from the largely {0001} planes of the rods are lower in energy with respect to those obtained from the other sample dominated by the side planes of {10 0}. Optical anisotropy in the transition amplitudes of the TR spectra for the vertical- and lateral-growth ZnO nanorods is found. Temperature dependence of transition energies of the ZnO nanorods is analyzed. The optical anisotropic behavior for the vertical- and lateral-growth ZnO nanorods is discussed. The PL spectra show the A、B transitions are the dominant luminescence excitons in the ZnO nanorods. Besides, ZnO/Si and ZnO/Sapphire have some defect enrgy levels inside the crystals. The defect levels may result in a strong luminescence of ~1.6eV present in the PL spectra of both ZnO/Si and ZnO/Sapphire samples.
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Liu, Han-Chun, and 劉漢鈞. "Optical characteristics of InN nanorods." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/gp6mar.
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碩士國立中央大學
物理研究所
94
We present results of Raman spectra and PL spectra to analyze the optical properties of InN nanorods. We find that the raman peak energy of InN nanorods is almost the same as InN thin film, and when the diameter of InN nanorods decrease, raman spectra will asymmetric, this is phonon confinement effect, and we use this model to fit our raman spectra, try to fit the diameter of InN nanorods. Finally, we find that the PL peak energy of InN nanorods will blue shift by decreasing the diameter of InN nanorods, this is quantum confinement effect.
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Liu, Cheng-Chung, and 劉誠洲. "Photodetectors based on the composites consisting of ZnO nanorods, CdTe quantum dots and Au nanorods." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/33902322347870828015.
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碩士國立臺灣大學
物理研究所
99
In this thesis a new ultraviolet (UV) photodetectors based on the composites consisting of ZnO nanorods, CdTe quantum dots and Au nanorods are fabricated and studied. The photodetectors were fabricated with a novel way by shorting the distance of electrodes to get better photoresponsivity. An obvious enhancement of photocurrent had been observed after CdTe quantum dots and Au nanorods deposited on the ZnO nanorods. The mechanism can be attributed to the type II band alignment between ZnO and CdTe. Additional Au nanorods deposited on the photodetectors can be used to intensify the absorbance of CdTe under 514-nm wavelength light. Considering the spectrum of photoresponse about ZnO and CdTe, this photodetectors show high efficiency and wide-range response.
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Schuster, Matthew. "Optical Antenna Photovoltaics & Making Metallic Nano-rods." Thesis, 2013. http://hdl.handle.net/1974/7727.
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Solar power is a clean, renewable source of energy. There is a growing demand for cheap, high efficiency photovoltaic cells. Of the many emerging solar harvesting technologies, a concept that has not been widely explored is that of optical antennas.
In 1972 Bailey et al.[1] explored scaling down of antenna technology to match the solar spectrum. A recent review was given by Lukas Novotny et al.[2], in which they outline the major hurdles as being the lack of reliable nano-fabrication and an inability to rectify into the Tera-hertz frequencies band.
Presently we aim to fabricate photovoltaic cells that incorporate an array of vertically aligned metallic nano-rods (MNR). Porous aluminum oxide (PAO) is used as a nano-structured template for growth of the MNR. PAO exhibit vertically aligned pores (D = 20 - 200nm) in a densely packed hexagonal arrangement. MNR fabrication is achieved through templated electrochemical deposition, and investigated with SEM and VIS-IR spectroscopy.
MNR samples have been specifically designed to be incorporated as a photoactive material for a novel photovoltaic cell. Through fine control of their length, the
MNR excitation energy can be tuned to the visible spectrum. Excitation of the MNR leads to energy transfer with localized acceptor molecules, creating a rectification of the field. The fabrication of MNR helps progress the development of the proposed antenna photovoltaic device.
[1] R. L. Bailey, “A Proposed New Concept for a Solar-Energy Converter," Journal
of Engineering for Power, pp. 73-77, Apr. 1972.
[2] P. Bharadwaj, B. Deutsch, and L. Novotny, “Optical Antennas," Advances in
Optics and Photonics, vol. 1, pp. 438-483, May 2009.Thesis (Master, Chemistry) -- Queen's University, 2013-01-07 12:36:57.17
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Fournier-Bidoz, Sebastien. "The nanochemist's toolbox: Nanospheres, nanorods, nanorings." 2005. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=232716&T=F.
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MO, ZH-YU, and 莫智羽. "Size effect study of DyMn2O5 nanorods." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/53899004961614738039.
Full textAbstract:
碩士中原大學
物理研究所
100
Two series of DyMn2O5 nanorods were synthesized by hydrothermal method in different time. They have different length by long axis with different annealing temperature. X-ray diffraction revealed the crystal structures are formed as orthorhombic Pbam phase for each sample. SAED results show that the long side of nanorods is parallel to c axis for all three samples. Magnetic ac susceptibility measurements were used to determinate magnetic properties. Curie-Weiss law is employed to analysis the ac magnetic susceptibility curves. It is found that Néel temperature is increased with increasing length. Antiferromagnetic peaks at around 38 and 43 K were only observed as length longer than 46 nm, which implied a critical length of magnetic ordering at around 50 nm.
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Yu-ChunChen and 陳郁鈞. "Exploration of TiO2 nanorods using sputtering." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/12054738303820943892.
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碩士國立成功大學
材料科學及工程學系碩博士班
100
In this study, two methods to grow the TiO2 nanorod structures were investigated: the RIE (reactive ion etching) approach and a seed layer approach using sputtering. For the RIE study, different RIE conditions were explored to make different degree of roughness on the Si substrates to see how it affects the growth of TiO2 thin films. We found the surface morphology of the substrate not only influences the structures but also the crystallinity of the TiO2 film. Although nanorod structures were not yet obtained, nanostructured TiO2 such as nanoflowers was grown, which constitutes an area for future research. For the seed layer approach, different structures of seed layers with varied thicknesses using hydrothermal was adopted. Then, sputtering was employed to deposit a TiO2 film directly on top of the seed layers. We found the features of the seed layers will significantly affect the growth of the sputtered TiO2 films. The sputtering deposition power changes the growth mechanism of the TiO2 films as well due to the varied mobility of the sputtered atoms depositing on the substrate. We have studied a variety of combinations of different seed layers and deposition powers and found that higher density of the nanoparticles in the seed layers with lower deposition power is promising to get TiO2 nanorods.
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Huang, Chun-Hui, and 黃駿惠. "Surface Plasmon Resonance Mode of Nanorods." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/93915588101360868097.
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碩士國立臺灣大學
應用力學研究所
100
This thesis discussed plasmon phenomena of various nano-structures, especially plasmonic modes, including a single gold nanorod, a single silver nanorod and gold nanorod-dimer structures, excited by electromagnetic plane wave and/or electrical dipoles. Maxwell theory together with the multiple-multipole (MMP) method is used to analyze the near-field surface plasmon resonance (SPR) and the far-field radiation patterns as well as the local field enhancement factor. Results show that as the aspect ratio (AR) increases the corresponding wavelengths of plasmonic modes increase. For the case of normal incidence plane waves or symmetric bi-dipole, only odd modes are excited; while for the case of oblique incidence plane wave or asymmetry bi-dipole, both odd and even modes appeared. When dipole at the tip of nanorod, it can transfer energy to far end of nano-particle, in silver nanorods, the enhancement factors keep at 0.8. For the case of gold nanorod dimer structures, for dimer with two identical nanorods, the bandwidth of dipole mode increases, while the peak of quadrupole mode weakens. For dimer with two different nanorods, if the wavelength of the quadrupole of long rod is close to that of the dipole mode of short rod, there is also a Fano resonance associated with a Fano dip due to a strong coupling between two nanorods.
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Tu, Hao-Wei, and 塗浩瑋. "Size effect on multiferroics LuMn2O5 nanorods." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/11993388976154126665.
Full textAbstract:
碩士中原大學
物理研究所
101
Abstract Series of multiferroics LuMn2O5 nanorods were synthesized by hydrothermal method. Different sizes of nanorods were obtained by various annealing temperatures. X-ray diffraction, FE-TEM, and SAED techniques were employed to determine the crystal structure, composition, and purity. The SQUID was used to study magnetic properties. Varied temperature x-ray powder diffraction and Raman spectroscopy were employed to analyze the interplay between structure and magnetic properties. The sizes of nanorods were first determinate by counting the axial and radial lengths in TEM images. The average axial and radial lengths were labeled in the format of length × width. Four sizes of nanorod, 66(22) nm×18(5) nm, 78(38) nm×22(9) nm, 102(44) nm×23(8) nm and 91(35) nm×20(7) nm were thus obtained. High resolution images and SAED patterns indicated that the c-axis is parallel to the axial direction in all samples. In the brief, the axial length of all samples was used to label and write as
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Li, Dung-Lin, and 李東林. "ZnO nanorods as a pressure sensor." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/91380597642422748909.
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碩士國立暨南國際大學
電機工程學系
102
ZnO is one of the piezoelectric materials in which a voltage can be generated when a mechanical forces is applied. In this work, attempt was made to find out the feasibility of using ZnO nanorods as a pressure sensor. The ZnO nanorods used in this work were grown by hydrothermal method on Si substrate. Mechanical force applied to the ZnO nanorods array was achieved by pressing the nanorods with human fingers .Piezoelectric effect of ZnO nanorods prepared with different growth times and post-growth annealings was studied. We also investigated the effect of the distance between probes as well as the fingers’ position with respect to the probe. Our experimental results show that more voltage was generated when the distance between probes is farther separated, while the generated voltage becomes smaller as the fingers’ position was placed farther from the probe, Interestingly, the polarity of the generated voltage reverse when the ZnO nanorods were subjected to post-growth annealing. In this thesis, the experimental results observed were explained by the existing theory.
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Lee, Chien-Liang, and 李建良. "Syntheses and Properties of Gold Nanorods." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/67368438960692090669.
Full textAbstract:
碩士國立中正大學
化學研究所
86
Aqueous solutions containing a high yield of suspended gold nanorods have beensuccessfully synthesized via an electrochemical method. By controlling silverfilm area and the amount of AgNO3﹙aq﹚in electrolysis can prepare different aspect ratio gold nanorods. As increasing silver film area gold nanorod absorption band can be tuned effectively to near Ir region. The absorptionspectral features show a dominant surface plasma band corresponding to the changing of aspect ratio and its λmax shifts markedly to the red as the aspect ratio is increased. Meanwhile, the dependence of λmax on the meanaspect ratio coincides with the classical electrostatic model prediction beforemean aspect ratios around 7.By controlling MPTMS （(3-Mercaptopropyl)trimethoxysilane） and sodium silicate solution concentration, we also havesuccessfully synthesized gold nanorods and nanospheres coated with nanoscale thickness silica. As thickness of silica coated on gold nanospheres increases,the absorption band shifts continuously to the red and the absorbance at thecorresponding *max increases. However, the absorption band of gold nanorods coated with silica red shifts and the absorbance decreases which the thicknessof silica is increased.Besides, we study the optical properties of silica glass with dispersed gold nanorods and nanospheres embedded inside.We find the absorption bands for both gold nanospheres and nanorods implantedn silica glass is also red-shifted compared to the case for those dispersed in water.
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Yang, Li-Hong, and 楊立宏. "Transparent ZnO nanorods thin film transistors." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/992a34.
Full textAbstract:
碩士中原大學
電子工程研究所
107
Zinc oxide (ZnO) is a very important material for transparent thin film transistors. It has high energy gap, high mechanical properties, and thermal stability. It can also be prepared in many ways, such as chemical vapor deposition, sol-gel method, and hydrothermal method. Well-aligned vertically oriented zinc oxide (ZnO) nanorod arrays on polymethylmethacrylate (PMMA) thin film were fabricated by sol-gel and hydrothermal method. Solution-processed ZnO thin films not only possess low resistivity but also high transmission. Following, transparent thin film transistors (TFT) were fabricated by using ZnO nanorod arrays as channel layer. In addition, in order to make the PMMA dielectric layer have good contact with the ZnO channel layer, we used a UV ozone lamp to modify the surface of the PMMA dielectric layer. This study were carried out in a low temperature aqueous solution method, so the production cost was quite low and it was suitable for a large-area process. Moreover, we successfully controlled the growth of ZnO nanorad arrays by changing the growth time of the hydrothermal method. Therefore, it can be applied to flexible substrates in the future.
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"Growth and characterization of ZnO nanorods." 2004. http://library.cuhk.edu.hk/record=b5892037.
Full textAbstract:
Hung Ngar Chun = 氧化鋅納米棒的生長和表徵 / 洪雅真.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references.
Text in English; abstracts in English and Chinese.
Hung Ngar Chun = Yang hua xin na mi bang de sheng zhang he biao zheng / Hong Yazhen.
Acknowledgements --- p.i
Abstract --- p.ii
摘要 --- p.iii
List of Tables --- p.iv
List of Figures --- p.v
Table of contents --- p.vii
Chapter Chapter 1 --- Introduction
Chapter 1.1. --- Objectives --- p.1-1
Chapter 1.2. --- Background --- p.1-1
Chapter 1.2.1. --- Nanomaterials --- p.1-1
Chapter 1.2.1.1. --- From three-dimensional to one-dimensional --- p.1-1
Chapter 1.2.1.2. --- One-dimensional nanomaterials --- p.1-2
Chapter 1.2.2. --- Characteristics and potential applications --- p.1-2
Chapter 1.2.3. --- Growth mechanisms --- p.1-4
Chapter 1.2.3.1. --- The VLS growth --- p.1-4
Chapter 1.2.3.2. --- The VS growth --- p.1-5
Chapter 1.2.4. --- ZnO --- p.1-6
Chapter 1.2.4.1. --- Characteristics and potential applications --- p.1-6
Chapter 1.2.4.2. --- Recent works performed by the others --- p.1-7
Chapter 1.2.4.2.1. --- Different fabrication systems --- p.1-7
Chapter 1.2.4.2.2. --- Different morphologies and shapes --- p.1-8
Chapter 1.3. --- Our work --- p.1-9
Chapter 1.3.1. --- Advantages of our fabrication method --- p.1-9
Chapter 1.4. --- Thesis layout --- p.1-9
References --- p.1-10
Figures --- p.1-13
Tables --- p.1-14
Chapter Chapter 2 --- Methodology and Experiments
Chapter 2.1. --- Introduction --- p.2-1
Chapter 2.2. --- The setup --- p.2-1
Chapter 2.2.1. --- Preparation of substrate --- p.2-1
Chapter 2.2.2. --- Chamber pressure and gas flow rate --- p.2-2
Chapter 2.2.3. --- Heating profile --- p.2-2
Chapter 2.3. --- The two important growth parameters --- p.2-3
Chapter 2.3.1. --- Substrate compositions --- p.2-3
Chapter 2.3.2. --- Temperature --- p.2-3
Chapter 2.4. --- Methods of characterizations --- p.2-4
Chapter 2.4.1. --- Morphology --- p.2-4
Chapter 2.4.1.1. --- SEM --- p.2-4
Chapter 2.4.1.2. --- TEM --- p.2-5
Chapter 2.4.2. --- Phases and Microstructures --- p.2-5
Chapter 2.4.2.1. --- XRD --- p.2-5
Chapter 2.4.2.2. --- HRTEM --- p.2-5
Chapter 2.4.3. --- Cathodoluminescence --- p.2-6
References --- p.2-7
Figures --- p.2-8
Chapter Chapter 3 --- Results
Chapter 3.1. --- Introduction --- p.3-1
Chapter 3.2. --- General Morphologies --- p.3-1
Chapter 3.3. --- Microstructural analysis --- p.3-2
Chapter 3.4. --- Samples sintered using substrate of different composition --- p.3-2
Chapter 3.5. --- Samples sintered at different temperatures --- p.3-4
Chapter 3.6. --- The cathodoluminescence of the ZnO nanorods --- p.3-4
References --- p.3-6
Figures --- p.3-7
Chapter Chapter 4 --- Discussions
Chapter 4.1. --- Introduction --- p.4-1
Chapter 4.2. --- Proposed growth model --- p.4-1
Chapter 4.2.1. --- Chemical reactions --- p.4-1
Chapter 4.2.2. --- Justification on the effect of residue oxygen and leakage --- p.4-2
Chapter 4.2.3. --- Justification on the possibility of VLS growth --- p.4-3
Chapter 4.2.4. --- Coarsening mechanisms --- p.4-3
Chapter 4.2.4.1. --- Oswald Ripening --- p.4-4
Chapter 4.2.4.2. --- Preferential growth direction --- p.4-4
Chapter 4.3. --- The effects of substrate composition --- p.4-5
Chapter 4.3.1. --- Roles of Si and Si02 --- p.4-5
Chapter 4.4. --- The effects of temperature --- p.4-6
Chapter 4.4.1. --- Range of sintering temperature --- p.4-6
Chapter 4.4.2. --- Diameter of the rods --- p.4-7
Chapter 4.4.3. --- Luminescence behavior --- p.4-7
References --- p.4-10
Figures --- p.4-11
Chapter Chapter 5 --- Conclusions and future works