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Sonochemical Synthesis And Growth Kinetics Of Zinc Oxide Nanowires And Zinc Oxide Nanowalls For Sensor Applications
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Book Synopsis Sonochemical Synthesis and Growth Kinetics of Zinc Oxide Nanowires and Zinc Oxide Nanowalls for Sensor Applications by : Avinash Pradeep Nayak
Download or read book Sonochemical Synthesis and Growth Kinetics of Zinc Oxide Nanowires and Zinc Oxide Nanowalls for Sensor Applications written by Avinash Pradeep Nayak and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sonochemical growth of zinc oxide (ZnO) nanowires and nanowalls is a relatively new synthetic technique that allows for room ambient growth and large scale production. This synthesis technique allows for services ranging from gas sensors and UV switches. In comparison to the widely used hydrothermal method of growth at low-temperatures, the sonochemical technique is found to be advantageous from the environmental impact, scalability, process time and production cost viewpoints. Using the sonochemical method, ZnO thin films, nanowires, and nanowalls, were synthesized. Although many applications can result from these nano-materials, we focus on ultraviolet (UV) photo-detectors and gas sensors. This method promises a mass-manufacturable process for fast and inexpensive ZnO nanowire production for practical low cost electronics, photonics and energy conversion applications.
Book Synopsis Zinc Oxide Nanostructures: Synthesis and Characterization by : Sotirios Baskoutas
Download or read book Zinc Oxide Nanostructures: Synthesis and Characterization written by Sotirios Baskoutas and published by MDPI. This book was released on 2018-12-04 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Zinc Oxide Nanostructures: Synthesis and Characterization" that was published in Materials
Book Synopsis Synthesis and Surface Chemistry of Zinc Oxide Nanowires for Chemical Sensor Applications by : Anurag Gupta
Download or read book Synthesis and Surface Chemistry of Zinc Oxide Nanowires for Chemical Sensor Applications written by Anurag Gupta and published by . This book was released on 2014 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research work in this dissertation comprises of synthesis and functionalization of high quality ZnO nanowires for highly sensitive and selective p-nitrophenol vapor sensor. High-quality ZnO nanowires were synthesized through a vapor-liquid-solid process in a customized chemical vapor deposition furnace. Scanning electron microscopy, transmission electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy were used to characterize morphology, crystal structure and composition. Surface functionalization behavior of pristine ZnO nanowires was tested by oleic acid as a model compound and the surface modification was studied using surface sensitive techniques of Raman and FT-IR spectroscopies. Surface functionalization of ZnO nanowires with optically active 1-pyrenebutyric acid was investigated. A 1-pyrenebutyric acid compound was grafted on a solid-state ZnO nanowires backbone. Optical and electrical properties of this heterostructure were determined through fluorescence and I-V measurements, respectively. Two distinct approaches for device fabrication were tested for integrated system development and validation of sensor operation. A single nanowire device and a multi-nanowire array device were successfully fabricated.
Book Synopsis Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications by : Hatim Alnoor
Download or read book Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications written by Hatim Alnoor and published by Linköping University Electronic Press. This book was released on 2017-10-06 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: One-dimensional (1D) nanostructures (NSs) of Zinc Oxide (ZnO) such as nanorods (NRs) have recently attracted considerable research attention due to their potential for the development of optoelectronic devices such as ultraviolet (UV) photodetectors and light-emitting diodes (LEDs). The potential of ZnO NRs in all these applications, however, would require synthesis of high crystal quality ZnO NRs with precise control over the optical and electronic properties. It is known that the optical and electronic properties of ZnO NRs are mostly influenced by the presence of native (intrinsic) and impurities (extrinsic) defects. Therefore, understanding the nature of these intrinsic and extrinsic defects and their spatial distribution is critical for optimizing the optical and electronic properties of ZnO NRs. However, identifying the origin of such defects is a complicated matter, especially for NSs, where the information on anisotropy is usually lost due to the lack of coherent orientation. Thus, the aim of this thesis is towards the optimization of the lowtemperature solution-based synthesis of ZnO NRs for device applications. In this connection, we first started with investigating the effect of the precursor solution stirring durations on the deep level defects concentration and their spatial distribution along the ZnO NRs. Then, by choosing the optimal stirring time, we studied the influence of ZnO seeding layer precursor’s types, and its molar ratios on the density of interface defects. The findings of these investigations were used to demonstrate ZnO NRs-based heterojunction LEDs. The ability to tune the point defects along the NRs enabled us further to incorporate cobalt (Co) ions into the ZnO NRs crystal lattice, where these ions could occupy the vacancies or interstitial defects through substitutional or interstitial doping. Following this, high crystal quality vertically welloriented ZnO NRs have been demonstrated by incorporating a small amount of Co into the ZnO crystal lattice. Finally, the influence of Co ions incorporation on the reduction of core-defects (CDs) in ZnO NRs was systematically examined using electron paramagnetic resonance (EPR).
Book Synopsis Piezoelectric Nanostructures of Zinc Oxide: Synthesis, Characterization and Devices by : Puxian Gao
Download or read book Piezoelectric Nanostructures of Zinc Oxide: Synthesis, Characterization and Devices written by Puxian Gao and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, a systematic study has been carried out on the synthesis, characterization and device fabrication of piezoelectric ZnO nanstructures. The achieved results are composed of the following four parts. Firstly, through a systematic investigation on the Sn-catalyzed ZnO nanostructure, an improved understanding of the chemical and physical process occurring during the growth of hierarchical nanostructures has been achieved. Decomposed Sn from SnO2 has been successfully demonstrated and proved to be an effective catalyst guiding the growth of not only aligned ZnO nanowires, but also the hierarchical nanowire-nanoribbon junction arrays and nanopropeller arrays. During the vapor-liquid-solid (VLS) catalyzing growth process at high temperature, Sn in the liquid state has been proved to be able to guide the growth of nanowires and nanoribbons in terms of growth directions, side facets, and crystallographic interfaces between Sn and ZnO nanostructures. Secondly, using pure ZnO as the only source material, by precisely tuning and controlling the growth kinetics, a variety of hierarchical polar surface dominated nanostructures have been achieved, such as single crystal nanorings, nanobows, nanosprings and superlattice nanohelices. High yield synthesis of ZnO nanosprings over 50% has been successfully obtained by mainly controlling the pre-pumping level associated with the partial pressure of residual oxygen during the vapor-solid growth process. The rigid superlattice nanohelices of ZnO have been discovered, which is a result of minimization of the electrostatic energy induced by polar surfaces. The formation process of the nanohelix has been systematically characterized. Thirdly, two new strategies have been successfully developed for fabricating ZnO quantum dots and synthesis of ZnO nanodiskettes and nanotubes. The formation process is based on a common concept of self-assembly. Finally, a series of devices and applications studies based on several piezoelectric ZnO nanostructures, such as nanobelts, nanopropellers and nanohelices, have been carried out utilizing the electro-mechanical resonance, bio-surface functionalization, devices fabrication and electrical characterization. Individual nanobelt and nanohelix based nanodevices have been successfully fabricated for applications in chemical and biological sensing. The study opens a few new areas in oxide nanostructures and applications.
Book Synopsis Zinc Oxide Based Nano Materials and Devices by : , Prof. Dr. Ahmed Nahhas
Download or read book Zinc Oxide Based Nano Materials and Devices written by , Prof. Dr. Ahmed Nahhas and published by BoD – Books on Demand. This book was released on 2019-10-09 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a review of recent advances in ZnO-based nanomaterials and devices. ZnO as a nanomaterial has gained substantial interest in the research area of wide bandgap semiconductors and is considered to be one of the major candidates for electronic and photonic applications. ZnO has distinguished and interesting electrical and optical properties and is considered to be a potential material in optoelectronic applications such as solar cells, surface acoustic wave devices, and UV emitters. ZnO's unique properties have attracted several researchers to study its electrical and optical properties. As a nanostructured material, ZnO exhibits many advantages for nanodevices. Moreover, it has the ability to absorb the UV radiation.
Book Synopsis Zinc Oxide Bulk, Thin Films and Nanostructures by : Chennupati Jagadish
Download or read book Zinc Oxide Bulk, Thin Films and Nanostructures written by Chennupati Jagadish and published by Elsevier. This book was released on 2011-10-10 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: With an in-depth exploration of the following topics, this book covers the broad uses of zinc oxide within the fields of materials science and engineering: - Recent advances in bulk , thin film and nanowire growth of ZnO (including MBE, MOCVD and PLD), - The characterization of the resulting material (including the related ternary systems ZgMgO and ZnCdO), - Improvements in device processing modules (including ion implantation for doping and isolation ,Ohmic and Schottky contacts , wet and dry etching), - The role of impurities and defects on materials properties - Applications of ZnO in UV light emitters/detectors, gas, biological and chemical-sensing, transparent electronics, spintronics and thin film
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:
Download or read book Nanowires written by Luke J. Wilson and published by Nova Science Publishers. This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc Oxide (ZnO) is a metal oxide semiconductor of group II-IV whose nature resides at the borderline between covalent and ionic semiconductors. In the last decade it has raised several attention in the research field since it possesses promising catalytic, electrical, electronic and optical properties. It can be easily prepared in different shapes and sizes at both the micrometric and nanometric scale, including the forms of micro- and nanowires, nanobelts, nanotubes, micro- and nanoparticles, multipods, tetrapods, and flower-like microstructures. This different variety of morphologies has thus attracted considerable attention for potential application in solar cells, nanogenerators, field effect transistors, gas sensors and other electronic micro- and nanodevices. This book discusses the synthesis and the electrical properties of ZnO nanowires. It also discusses rough silver nanowires, nanobuds and nanoparticle substrates; the synthesis and properties of Ni nanowires in porous silicon templates; and phonon scattering and elastic energy propagation in nanowires.
Book Synopsis Nanostructured Zinc Oxide by : Kamlendra Awasthi
Download or read book Nanostructured Zinc Oxide written by Kamlendra Awasthi and published by Elsevier. This book was released on 2021-08-10 with total page 781 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured Zinc Oxide covers the various routes for the synthesis of different types of nanostructured zinc oxide including; 1D (nanorods, nanowires etc.), 2D and 3D (nanosheets, nanoparticles, nanospheres etc.). This comprehensive overview provides readers with a clear understanding of the various parameters controlling morphologies. The book also reviews key properties of ZnO including optical, electronic, thermal, piezoelectric and surface properties and techniques in order to tailor key properties. There is a large emphasis in the book on ZnO nanostructures and their role in optoelectronics. ZnO is very interesting and widely investigated material for a number of applications. This book presents up-to-date information about the ZnO nanostructures-based applications such as gas sensing, pH sensing, photocatalysis, antibacterial activity, drug delivery, and electrodes for optoelectronics. Reviews methods to synthesize, tailor, and characterize 1D, 2D, and 3D zinc oxide nanostructured materials Discusses key properties of zinc oxide nanostructured materials including optical, electronic, thermal, piezoelectric, and surface properties Addresses most relevant zinc oxide applications in optoelectronics such as light-emitting diodes, solar cells, and sensors
Book Synopsis Zinc Oxide Nanostructures by : Magnus Willander
Download or read book Zinc Oxide Nanostructures written by Magnus Willander and published by CRC Press. This book was released on 2014-07-22 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) in its nanostructured form is emerging as a promising material with great potential for the development of many smart electronic devices. This book presents up-to-date information about various synthesis methods to obtain device-quality ZnO nanostructures. It describes both high-temperature (over 100° C) and low-temperature (under 100° C) approaches to synthesizing ZnO nanostructures; device applications for technical and medical devices, light-emitting diodes, electrochemical sensors, nanogenerators, and photodynamic therapy; and the concept of self-powered devices and systems using ZnO nanostructures. The book emphasizes the utilization of non-conventional substrates such as plastic, paper, and textile as new platforms for developing electronics.
Book Synopsis Synthesis of Zinc Oxide by Sol–Gel Method for Photoelectrochemical Cells by : Siti Salwa Alias
Download or read book Synthesis of Zinc Oxide by Sol–Gel Method for Photoelectrochemical Cells written by Siti Salwa Alias and published by Springer Science & Business Media. This book was released on 2013-11-20 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the study of synthesized ZnO powder using Zn(CH3COO)2∙2H2O precursor, methanol (as solvent), and sodium hydroxide (NaOH) to vary the pH. The successfully synthesized ZnO powder from the sol-gel centrifugation and sol-gel storage methods were characterized and investigated by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, UV–visible spectroscopy, and photoluminescence test to compare the properties of the nanoparticles. The best characteristic of the ZnO powder from both methods was observed when the powders were coated on an ITO glass to fabricate a PEC. The current density–voltage performances of both PECs were investigated under luminescent and dark conditions.
Book Synopsis Synthesis and Functionalization of Zinc Oxide Nanowires by : Jia Xu (Ph.D.)
Download or read book Synthesis and Functionalization of Zinc Oxide Nanowires written by Jia Xu (Ph.D.) and published by . This book was released on 2017 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide nanowires (NWs) have broad applications in various fields such as nanoelectronics, optoelectronics, piezoelectric nanogenerators, chemical/biological sensors, and heterogeneous catalysis. To meet the requirements for broader applications, the growth of high-quality ZnO NWs and functionalization of ZnO NWs are critical. In this work, specific types of functionalized ZnO NWs have been synthesized and correlations between specific structures and properties have been investigated. Deposition of Îþ-Bi2O3 (narrow band gap) epilayers onto ZnO (wide band gap) NWs improves the absorption efficiency of the visible light spectrum by 70%. Furthermore, the deposited Îþ-Bi2O3 grows selectively and epitaxially on the {11-20} but not on the {10-10} facets of the ZnO NWs. The selective epitaxial deposition and the interfacial structure were thoroughly investigated. The morphology and structure of the Bi2O3/ZnO nanocomposites can be tuned by controlling the deposition conditions. Various deposition methods, both physical and chemical, were used to functionalize the ZnO NWs with metal or alloy nanoparticles (NPs) for catalytic transformations of important molecules which are relevant to energy and environment. Cu and PdZn NPs were epitaxially grown on ZnO NWs to make them resistant to sintering at elevated temperatures and thus improved the stability of such catalytic systems for methanol steam reforming (MSR) to produce hydrogen. A series of Pd/ZnO catalysts with different Pd loadings were synthesized and tested for MSR reaction. The CO selectivity was found to be strongly dependent on the size of the Pd: Both PdZn alloy and single Pd atoms yield low CO selectivity while Pd clusters give the highest CO selectivity. By dispersing single Pd atoms onto ZnO NWs, Pd1/ZnO single-atom catalysts (SACs) was synthesized and their catalytic performance was evaluated for selected catalytic reactions. The experimental results show that the Pd1/ZnO SAC is active for CO oxidation and MSR but is not desirable other reactions. We further synthesized ZnO NWs supported noble metal (M1/ZnO; M=Rh, Pd, Pt, Ir) SACs and studied their catalytic performances for CO oxidation. The catalytic test data shows that all the fabricated noble metal SACs are active for CO oxidation but their activity are significantly different. Structure-performance relationships were investigated.
Book Synopsis Chemically Modified Metal Oxide Nanostructures Electrodes for Sensing and Energy Conversion by : Sami Elhag
Download or read book Chemically Modified Metal Oxide Nanostructures Electrodes for Sensing and Energy Conversion written by Sami Elhag and published by Linköping University Electronic Press. This book was released on 2017-02-02 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this thesis is the development of scalable, low cost synthesis of metal oxide nanostructures based electrodes and to correlate the chemical modifications with their energy conversion performance. Methods in energy conversion in this thesis have focused on two aspects; a potentiometric chemical sensor was used to determine the analytical concentration of some components of the analyte solution such as dopamine, glucose and glutamate molecules. The second aspect is to fabricate a photo-electrochemical (PEC) cell. The biocompatibility, excellent electro-catalytic activities and fast electron transfer kinetics accompanied with a high surface area to volume ratio; are properties of some metal oxide nanostructures that of a potential for their use in energy conversion. Furthermore, metal oxide nanostructures based electrode can effectively be improved by the physical or a chemical modification of electrode surface. Among these metal oxide nanostructures are cobalt oxide (Co3O4), zinc oxide (ZnO), and bismuth-zincvanadate (BiZn2VO6) have all been studied in this thesis. Metal oxide nanostructures based electrodes are fabricated on gold-coated glass substrate by low temperature (< 100 0C) wet chemicalapproach. X-ray diffraction, x-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the electrodes while ultraviolet-visible absorption and photoluminescence were used to investigate the optical properties of the nanostructures. The resultant modified electrodes were tested for their performance as chemical sensors and for their efficiency in PEC activities. Efficient chemically modified electrodes were demonstrated through doping with organic additives like anionic, nonionic or cationic surfactants. The organic additives are showing a crucial role in the growth process of metal oxide nanocrystals and hence can beused to control the morphology. These organic additives act also as impurities that would significantly change the conductivity of the electrodes. However, no organic compounds dependence was observed to modify the crystallographic structure. The findings in this thesis indicate the importance of the use of controlled nanostructures morphology for developing efficient functional materials.
Book Synopsis Zinc Oxide Nanorods by : Kai-Hang Tam
Download or read book Zinc Oxide Nanorods written by Kai-Hang Tam and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Zinc Oxide Nanorods: Hydrothermal Growth, Properties and Applications" by Kai-hang, Tam, 譚啟鏗, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled ZINC OXIDE NANORODS: HYDROTHERMAL GROWTH, PROPERTIES AND APPLICATIONS Submitted by Tam Kai Hang for the degree of Master of Philosophy at The University of Hong Kong in December 2007 One-dimensional wide band-gap semiconductor nanostructures, such as nanorods, nanowires and nanobelts, have recently attracted much attention for their potential use as fundamental building blocks for new generation of electronic and photonic devices. Various semiconducting 1-D nanostructures have been synthesized, such as TiO, SnO, 2 2 GaN, GaAs, Si and ZnO. Among these nanostructures, zinc oxide (ZnO) has became particularly intersting in optoelectronic, field emission, gas sensing and biomedicine applications. ZnO is a wide band-gap (3.37 eV) semiconductor with high excitonic binding energy ( 60 meV), and it is non-toxic and environmentally friendly. Hydrothermal growth of ZnO provides an inexpensive method to fabricate large amounts of ZnO nanorods or nanowires on various substrates. However, the controversies still remain about the native defects in ZnO. In this work, ZnO nanorod arrays were fabricated by a hydrothermal method. The structural properties were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD). Well-oriented nanorods, which exhibited strong defect-related photoluminescence (PL) were obtained. Stimulated UV emission was achieved in forming gas or oxygen annealed nanorods. Change in lasing threshold and defect emission, as well as spontaneous decay time, indicated that yellow defect emission was not caused by interstitial oxygen, which was commonly assumed to be dominant in the yellow emitted ZnO. The origins of defects emissions were investigated by x-ray photoelectron spectroscopy (XPS) and positron annihilation spectroscopy (PAS). The results showed that yellow emission of the as-grown nanorods originated from the presence of Zn(OH) on surface, while the green emission which appeared after annealing was due to the defect complex related to zinc vacancy. On the other hand, it was also observed that green emission originated from grain boundary in other ZnO nanostructures, such as nanoshells. The origin of the green emission has not yet been determined, but there was evidence that the emission was surface-related. Heterojunction of n-ZnO nanorod arrays / p-GaN film light-emitting-diodes (LEDs) were fabricated. Influence of annealing conditions on the performance of devices was examined. It was found that the position of recombination zone was shifted after annealing in some cases. Emission wavelength could be controlled through annealing processes. This study could help improve the performance of these heterojunction devices. In order to have more comprehensive studies on applications of these versatile ZnO nanorods, antibacterial properties of the nanorods were investigated. ZnO nanorods coating have exhibited great antibacterial activity. Other ZnO morphologies (nanoparticles and powder) were also studies for comparison. Mechanisms of ZnO against different bacteria were investigated. It was found that damaging of E. coli cell was partly due to the relaxation of hydrogen peroxide (H O ) from the structures. 2 2 DOI: 10.5353/th_b3955734 Subjects: Zinc oxide Nanostructures Nanotechnology
Book Synopsis Fabrication and Characterization of Piezoelectric Zinc Oxide Nanowire Sensor by : Zacharia Tharakan
Download or read book Fabrication and Characterization of Piezoelectric Zinc Oxide Nanowire Sensor written by Zacharia Tharakan and published by . This book was released on 2017 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: The biosensor field is rapidly accelerating in recent years. Among many types of biosensors available today, piezoelectric (PZT) class of materials are becoming very popular. In this thesis, Zinc Oxide nanowire PZT biosensor was fabricated and characterized to detect the presence of fungi which has some huge economic implications in US agriculture industry. Zinc Oxide nanowires were synthesized in a mass scale via wet solution method in a controlled temperature and growth environment. Different substrates including glass, indium tin oxide, and gold coated silicon substrates were utilized to grow the nanowires followed by layering with silane and subsequently etching them. The results show that the nanowires were grown homogenously on gold coated silicon wafers with cylindrical structures. The ideal morphology of the nanowires was found to be dependent on: incubation time, incubation temperature, and substrate material. Substrate catalyst was also varied from Au & Pd to pure Au which showed significant improvement in producing the nanowires. A systematic variation of hours was implemented from: 3, 5, 7, 9, 11, and 13 hours. Zinc Oxide nanowire features such as length, diameter, and aspect ratio were quantified through SEM micrographs. Linear increase in height, diameter, and aspect ratio was observed up to 13 hours along with density. The optimal condition for nanowire growth was determined at: 80 °C and 5 hours. Energy dispersive spectroscopy aided in generating presence of specific elements on the biosensor. Raman helps in verifying chemical composition of the device. Both Raman and EDS spectroscopy aided in enhancement and individualization of the biosensor at different proposed parameters. Keithley readings represented series of current-voltage (I-V) measurements under different forward biased voltages. The response of nanowires from these I-V measurements show a diode-like response. Next, nanowire displacement patterns of fungi, Fusarium proliferatum (F. proliferatum) were studied by I-V measurements. When I-V measurements were conducted on PZT nanowires in the presence of F. proliferatum a strong association from microbe attachment and growth was observed showing an increase in switch-on voltage with a 2V sweep. It is speculated that the observed high resistance is a result of mechanical movement of fungi on the piezoelectric device. Future studies will be designed to investigate this phenomenon. These results indicate that by simply reading the characteristic current-voltage measurement, one can better evaluate microbe pattern of displacement and maturation. Future application of this nanowire platform can characterize distinct displacement signature of disease carrying organism much more efficiently.
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.
