Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Controlled Synthesis And Understanding Of Growth Mechanism Parameters For Atmospheric Pressure Hydrothermal Synthesis Of Ultrathin Secondary Zno Nanowires
Download Controlled Synthesis And Understanding Of Growth Mechanism Parameters For Atmospheric Pressure Hydrothermal Synthesis Of Ultrathin Secondary Zno Nanowires full books in PDF, epub, and Kindle. Read online Controlled Synthesis And Understanding Of Growth Mechanism Parameters For Atmospheric Pressure Hydrothermal Synthesis Of Ultrathin Secondary Zno Nanowires ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Controlled Synthesis and Understanding of Growth Mechanism - Parameters for Atmospheric Pressure Hydrothermal Synthesis of Ultrathin Secondary ZnO Nanowires by :
Download or read book Controlled Synthesis and Understanding of Growth Mechanism - Parameters for Atmospheric Pressure Hydrothermal Synthesis of Ultrathin Secondary ZnO Nanowires written by and published by . This book was released on 2015 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: We measured luminescence and scintillation in ZnO single crystals by photoluminescence and X-ray-induced luminescence (XRIL). XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. In the origin of green emission, the dominant trap emission in ZnO, was investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials or the surroundings. Moreover, the measurements showed the absence of positron traps in the crystals and yielded a bulk positron lifetime value that is in complete agreement with the predicted theoretical value = thereby confirming the advantage of the GIPS method. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE.
Book Synopsis Controlled Synthesis and Understanding of Growth Mechanism {u2013} Parameters for Atmospheric Pressure Hydrothermal Synthesis of Ultrathin Secondary ZnO Nanowires by :
Download or read book Controlled Synthesis and Understanding of Growth Mechanism {u2013} Parameters for Atmospheric Pressure Hydrothermal Synthesis of Ultrathin Secondary ZnO Nanowires written by and published by . This book was released on 2015 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: We measured luminescence and scintillation in ZnO single crystals by photoluminescence and X-ray-induced luminescence (XRIL). XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. In the origin of green emission, the dominant trap emission in ZnO, was investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials or the surroundings. Moreover, the measurements showed the absence of positron traps in the crystals and yielded a bulk positron lifetime value that is in complete agreement with the predicted theoretical value = thereby confirming the advantage of the GIPS method. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE.
Book Synopsis Hydrothermal Synthesis of Zinc Oxide Nanowire Arrays for Photovoltaic Applications by : Jian Wei Jayce Cheng
Download or read book Hydrothermal Synthesis of Zinc Oxide Nanowire Arrays for Photovoltaic Applications written by Jian Wei Jayce Cheng and published by . This book was released on 2016 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) nanowires with excellent crystal quality can be grown vertically aligned from a substrate using hydrothermal synthesis, a low-cost, scalable process that is compatible with many semiconductor processing techniques. However, precise control over nanowire array dimensions such as nanowire spacing, diameter, length, and alignment, which is important for optoelectronic device applications, has proven elusive due to lack of understanding regarding fundamental aqueous growth mechanisms at the nanoscale. Here, we utilize electron-beam lithography to template ZnO seed layers, demonstrating that seed layer engineering via judicious choice of seed deposition conditions and annealing can yield well-aligned nanowire arrays with single nanowire spatial precision on a variety of device relevant substrates. Subsequently, we use bottom-up patterning techniques and investigate the competition between diffusive transport and surface reaction in hydrothermal growth to achieve control over nanowire spacing and enhanced nanowire array uniformity over length scales suitable for photovoltaic (PV) device fabrication. By analyzing the role of temperature, concentration, and areal seed density on the balance between diffusion vs. reaction rates at the solution-nanowire interface, we show that the c-facet grows via the direct incorporation mechanism. With this knowledge, we use additives to shift the nanowire growth system into a reaction-limited regime, making nanowire growth rate independent of the patterned template. As a consequence, we achieve ZnO nanowire array uniformity that is critical for device applications.
Book Synopsis Rational Control of Hydrothermal Nanowire Synthesis and Its Applications by : Jaebum Joo
Download or read book Rational Control of Hydrothermal Nanowire Synthesis and Its Applications written by Jaebum Joo and published by . This book was released on 2010 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrothermal nanowire synthesis is a rapidly emerging nanowire discipline that enables low temperature growth and batch process. It has a major impact on the development of novel energy conversion devices, high density electronics, and optical devices. However, detailed growth mechanism is still in early stage of its development. This thesis presents the fundamental understanding of controlled zinc oxide nanowire synthesis in a hydrothermal system based on thermodynamic / kinetic analysis of heterogeneous chemical reactions. Governing parameters of hydrothermal growth were evaluated with experimental growth rates and calculated solubility plots. Supersaturation was shown to be a key parameter for the hydrothermal nanowire synthesis. Morphology control of the nanowire synthesis was tested with various additional cations during synthesis. Changes in morphology and aspect ratio with different cations were explained by electrostatic competing ion model. Based on experimental results and complex ion charge distribution, the growth direction was biased via electrostatic competition from cation-complexes that adsorb to the crystal in a face-specific manner, thereby reducing zinc ion-complex adsorption and suppressing growth along that face. Dynamic control of nanowire synthesis was investigated under microfluidic environment with continuous flow. Microfluidic growth conditions were analyzed with the parametric experiments and finite element modeling. Nanowire growth under complex geometry was also evaluated. This rational control of hydrothermal nanowire synthesis was applied to fabricate high efficiency alternative current electroluminescent devices, in-situ fabricated light emitting diodes, photovoltaic devices, and field emission devices.
Download or read book Nanowires written by Simas Rackauskas and published by BoD – Books on Demand. This book was released on 2019-04-10 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanowires are attracting wide scientific interest due to the unique properties associated with their one-dimensional geometry. Developments in the understanding of the fundamental principles of the nanowire growth mechanisms and mastering functionalization provide tools to control crystal structure, morphology, and the interactions at the material interface, and create characteristics that are superior to those of planar geometries. This book provides a comprehensive overview of the most important developments in the field of nanowires, starting from their synthesis, discussing properties, and finalizing with nanowire applications. The book consists of two parts: the first is devoted to the synthesis of nanowires and characterization, and the second investigates the properties of nanowires and their applications in future devices.
Book Synopsis Nanoengineering of ZnO Electrical and Optical Characteristics by Controlling Its Morphology and Defects Via Reaction Kinetics, Fluid Dynamics, and Stoichiometry in Low-pressure CVD Synthesis by : Taehoon Lim
Download or read book Nanoengineering of ZnO Electrical and Optical Characteristics by Controlling Its Morphology and Defects Via Reaction Kinetics, Fluid Dynamics, and Stoichiometry in Low-pressure CVD Synthesis written by Taehoon Lim and published by . This book was released on 2016 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: LPCVD synthesis and characterization of ZnO with diverse morphology for semiconducting applications are studied and discussed in this dissertation. Because nanoscale ZnO shows variant characteristics depending on its physical dimensions, morphology, and impurity concentration, the focus of this work is to control the structure and composition of ZnO by adjusting synthesis parameters and methods. In Chapter 2, the synthesis of ZnO with optimized concentration of oxygen vacancies and physical dimensions are discussed. Opaqueness of ZnO is derived from scattering due to its physical dimensions, but visible transparency for the photocatalytic application of ZnO for solar cell devices is required. By controlling the concentration of oxygen vacancies and physical dimensions, fluorescent and transparent ZnO is successfully synthesized. In Chapter 3, a method to stabilize precursor supply and to lower the reaction temperature is discussed. In CVD synthesis, the stable and continuous growth of ZnO is inhibited by the premature oxidation of Zn, and the formation of a zinc oxide layer that blocks the evaporation of Zn precursor. By controlling the fluid dynamics of precursor vapors, a low temperature synthesis method with higher product uniformity is developed. Using this method, a stable synthesis technique for producing high quality ZnO under low temperature is successfully achieved. In Chapter 4, the synthesis of ZnO under relatively low temperature is discussed. During LPCVD synthesis it is observed that as the distance from the source increases, the partial vapor pressure of Zn near the surface of the deposition substrate is drastically decreased (along the axis of gas flow), forming a dimensional gradient on a single substrate. The changing reactant ratio near the surface drives the non-uniformity of product in terms of morphology, physical dimensions, and impurity concentration. In Chapter 5, a novel template-free self-catalyzed synthesis technique for achieving ultra-thin ZnO nanowires is discussed. From the tip of synthesized hexagonal cone ZnO, ultra-thin ZnO nanowires are grown by self-catalysis.
Book Synopsis Study of Growth Kinetics in One Dimensional and Two Dimensional ZnO Nanostructures by : Xin Yin
Download or read book Study of Growth Kinetics in One Dimensional and Two Dimensional ZnO Nanostructures written by Xin Yin and published by . This book was released on 2017 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of the merits arising from the unique geometry, nanostructure materials have been an essential class of materials, which have shown great potentials in the fields of electronics, photonics, and biology. With various nanostructures being intensively investigated and successfully complemented into device applications, there has been one increasing demand to the investigation of the growth mechanism devoted to the controlled nanostructure synthesis. Motivated by this situation, this thesis is focused on the fundamental understanding of the nanostructure growth. Specifically, by taking zinc oxide as an example material, through controlling the basic driving force, that is, the supersaturation, I have rationally designed and synthesized various of nanostructures, and further applied the classical layer-by-layer growth mechanism to the understanding on the formation of these nanostructures, they are, the convex-plate-capped nanowires, the concave-plate-capped nanowires, the facet evolution at the tip of the nanowires, and the ultrathin 2D nanosheets.
Book Synopsis Synthesis, Integration and Application of ZnO Nanowires by : Lei Luo
Download or read book Synthesis, Integration and Application of ZnO Nanowires written by Lei Luo and published by . This book was released on 2007 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Controlling The Growth of ZnO Nanowires by Hydrothermal Method by : 林鴻偉
Download or read book Controlling The Growth of ZnO Nanowires by Hydrothermal Method written by 林鴻偉 and published by . This book was released on 2008 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Controlled Synthesis of ZnO Nanowires Towards the Fabrication of Solar Cells by : Dongshan Yu
Download or read book Controlled Synthesis of ZnO Nanowires Towards the Fabrication of Solar Cells written by Dongshan Yu and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, quasi-one-dimensional materials have attracted a lot of research attention due to their remarkable properties, and their potential as building blocks for nanoscale electronic and optoelectronic devices. A modified chemical vapor deposition (CVD) method has been used to synthesize ZnO nanowires. Electron microscopy and other characterization techniques show that nanowires having distinct morphologies when grown under different conditions. The effects of reaction parameters including reaction time, temperature, carrier gas flow rate, substrates and catalyst material upon the size, shape, and density of ZnO nanowire arrays have been investigated. Excitonic solar cells -including Gratzel-type cells, organic and hybrid organic/inorganic solar cells- are promising devices for inexpensive, large-scale solar energy conversion. Hybrid organic/inorganic solar cells are made from composites of conjugated polymers with nanostructure metal oxides, in which the polymer component serves the function of both light absorber and hole conductor, and the ZnO nanowire arrays act as the electron conductors. Organic solar cells have been fabricated from environmentally friendly water-soluble polymers and ZnO nanowire arrays.
Book Synopsis Hydrothermal Synthesis of Al-doped ZnO Nanowires and Their Application for Photovoltaic Devices by : Hyoungwon Park
Download or read book Hydrothermal Synthesis of Al-doped ZnO Nanowires and Their Application for Photovoltaic Devices written by Hyoungwon Park and published by . This book was released on 2014 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanostructures exhibit distinct properties by virtue of nano-scale dimensionality, resulting in recent interest in semiconducting nanowires for electronic, photonic, and energy applications. Along with nanowires, quantum dots are solution-processable nanocrystals with tunable band gap energies as a function of their size. Based on all of these promising properties that nanostructures exhibit, nanowires and quantum dots are excellent candidates for next-generation optoelectronic devices, including solar cells and light-emitting diodes. However, the realization of nanostructured materials for solar cell device applications is limited by the fundamental trade-off between light absorption and photocarrier collection. Vertically aligned ZnO nanowire arrays can decouple absorption and collection by acting as highly-conductive channels for extracting photogenerated electrons from deep within the film. This thesis illustrates a scheme for the development of ordered bulk heterojunction photovoltaic devices incorporating solution-based n-type doped ZnO nanowires and PbS quantum dots. In order to improve the electrical properties of ZnO nanowires, Al doping of hydrothermally synthesized ZnO nanowires is studied along with the optimization of doping concentration. The morphology of ZnO nanowire arrays is also studied as a function of the doping concentration in the growth solution. Finally, photovoltaic devices are fabricated and the effect of Al-doping of ZnO nanowires is investigated by device characterization techniques.
Book Synopsis Fundamental Understanding of the Growth, Doping and Characterization of Aligned ZNO Nanowires by : Gang Shen
Download or read book Fundamental Understanding of the Growth, Doping and Characterization of Aligned ZNO Nanowires written by Gang Shen and published by . This book was released on 2014 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) is a II-VI semiconductor whose wide direct bandgap (3.37 eV) and large exciton binding energy (60 meV) make it compelling for optoelectronic devices such as light emitting diodes, lasers, photodetectors, solar cells, and mechanical energy harvesting devices. One dimensional structures of ZnO (nanowires) have become significant due to their unique physical properties arising from quantum confinement, and they are ideal for studying transport mechanisms in one-dimensional systems. In this doctoral research work, ZnO nanowire (NW) arrays were synthesized on sapphire substrates through carbo-thermal reduction of ZnO powders, and the effects of growth parameters on the properties of ZnO NW arrays were studied by scanning and transmission electron microscopy, X-ray diffraction, photoluminescence and Raman spectroscopy. Based on the phonon mode selection rules in wurtzite ZnO, confocal Raman spectroscopy was used to assess the alignment of ZnO NWs in an array, thereby complementing X-ray diffraction. Al doped ZnO NW arrays were achieved by mixing Al powder into the ZnO and graphite source mixture, and the presence of Al was confirmed by Energy-dispersive X-ray spectroscopy. The incorporation of Al had the effects of lowering the electrical resistivity, slightly deteriorating crystal quality and suppressing defect related green emission. Two models of ZnO NW growth were developed by establishing the relationship between NW length and diameter for undoped and Al doped ZnO NWs separately. The growth of undoped ZnO NWs followed the diffusion-induced model which was characterized by thin wires being longer than thick wires, while the growth of Al doped ZnO was controlled by Gibbs-Thomson effect which was characterized by thin wires being shorter than thin wires. Local electrode atom probe analysis of ZnO NWs was carried out to study the crystal stoichiometry and Al incorporation. Undoped ZnO NWs were found to be high purity with no detectable impurities. Possible Al incorporation related peaks were observed in the mass spectrum of Al doped ZnO NWs. Further work on Al doped ZnO LEAP analysis is needed to better understand the Al dopant.
Book Synopsis Growth and Characterization of ZnO Nanowires by : Dong Sik Kim
Download or read book Growth and Characterization of ZnO Nanowires written by Dong Sik Kim and published by . This book was released on 2009 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fundamental aspects of growth and physical characteristic of the ZnO in the form of one-dimensional nanostructures are studied. In Au-assisted ZnO nanowire growth, Au nanoparticles are sometimes observed at the root of wires after growth and in other cases at the tip of the wires. A selection mechanism is proposed defining whether the Au particle remains on the substrate at the root of the nanowire serving as an initial template for wire nucleation or is lifted up from the substrate, catalyzing wire growth at the tip. In addition, it is demonstrated that the surface migration of Au atoms on a lattice matched substrate limits the position-controlled growth of ZnO nanowires. Based on the understanding of such nanowire growth behavior epitaxial grown ZnO nanowire arrays on GaN substrates are demonstrated which is important for device applications. By the use of laser interference lithography for patterning of Au nanodots, well arranged ZnO nanowires over larger area are fabricated. Since device applications based on ZnO nanowires require reliable p-type ZnO materials attempts to grow phosphorus-doped nanowires are made based on a single source precursor, Zn2P3. Single-crystalline phosphorus-doped ZnO nanowires are produced in a reproducible way. Low temperature PL spectra show that the presence of phosphorus strongly enhances a peak at 3.316 eV. However, the amphoteric nature of compensating native defects makes it difficult to realize stable and reliable p-type doping in ZnO nanowires. ZnO shows n-type conductivity without any intentional doping due to intrinsic native point defects. The influence of the relative content of residual oxygen during wire growth on the physical properties of the nanowire is studied by means of electrical transport as well as by photoluminescence. It is disclosed that the relatively high density of n-type defect density is observed in the ZnO nanowires grown under comparably oxygen poor conditions, which is attributed to the low formation energy of oxygen vacancies. Furthermore the relative free carrier densities are roughly estimated based on the intensity ratio between the surface exciton (SX) emission and the bound exciton emission.
Book Synopsis Synthesis of ZnO Nanowire by MOCVD Technique: Effect of Substrate and Growth Parameter by : Sachindra Nath Das
Download or read book Synthesis of ZnO Nanowire by MOCVD Technique: Effect of Substrate and Growth Parameter written by Sachindra Nath Das and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nanowires written by Xihong Peng and published by IntechOpen. This book was released on 2012-12-19 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: One dimensional nanoscale structures such as nanowires have drawn extensive research interests in recent years. The size miniature brings unique properties to nanowires due to quantum confinement. The large surface-to-volume ratio renders nanowires with high sensitivity to surface effects. The unique geometrical advantages and properties facilitate the utilization of nanowires in nano-electronics. InTech scientific publisher has initialized a series of books focusing on fundamental research in nanowires, which largely boosted the widespread of knowledge among the research society. This book is intended to provide an updated review on the applications of various nanowires and the associated advancements in synthesis and properties characterization. The topics include recent progress in metal oxide nanowires, silicon nanowires, carbon based nanotubes and nanowires.
Book Synopsis Growth of Zinc Oxide Nanowires on Various Semiconductor Wafers by Using Hydrothermal Synthesis by : Mounika Kodali
Download or read book Growth of Zinc Oxide Nanowires on Various Semiconductor Wafers by Using Hydrothermal Synthesis written by Mounika Kodali and published by . This book was released on 2018 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our aim is to grow zinc oxide (ZnO) nanowires on various semiconductor substrates by hydrothermal synthesis. To obtain porous silicon, electrochemical etching on the silicon substrate was performed. Electrochemical etching is the process of etching where a cathode, anode and an electrolyte are used. Here, we etch the samples using 1:3 HF: Acetonitrile and 1:3 HF: Ethanol. No nanowire growth is observed on the samples etched with HF: Acetonitrile. Very few nanowires are formed on the samples etched with HF: Ethanol. Very dense growth of nanowires is observed on non-porous silicon substrates. An equimolar mixture of Hexamethylenetetramine and Zinc Nitrate Hexahydrate is prepared and constantly stirred for about 5--10 min to obtain a pH ranging from 6.5--6.85. The samples are then dipped in the equimolar mixture of Hexamethylenetetramine and Zinc Nitrate Hexahydrate maintained at a constant temperature. At a longer growth rate, i.e. at after 16 hours we could grow nanowires on the porous silicon samples. The samples were then characterized using Scanning Electron Microscopy (SEM) and a uniform growth of Nanowires was obtained.
Book Synopsis Growth, Doping, and Characterization of ZnO Nanowires by : Svetlana Spitsina
Download or read book Growth, Doping, and Characterization of ZnO Nanowires written by Svetlana Spitsina and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
