Nanostructured Semiconductors Synthesized Using High Pressure Chemical Vapor Deposition With Nanoporous Templates
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Nanostructured Semiconductors Synthesized Using High Pressure Chemical Vapor Deposition With Nanoporous Templates
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Author : Briana Laubacker
language : en
Publisher:
Release Date : 2021
Nanostructured Semiconductors Synthesized Using High Pressure Chemical Vapor Deposition With Nanoporous Templates written by Briana Laubacker and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.
In this dissertation, nanostructured germanium and silicon prepared using porous templates with high pressure chemical vapor deposition (HPCVD) have been explored. Metal-organic frameworks (MOFs), mesoporous silicas, and mesoporous nitrogen-doped carbon (MPNC) all were investigated as template materials given their 3D connected structures and well-defined nanometer-sized pores. By depositing silicon or germanium within these templates, a nanostructured semiconductor can be synthesized with feature sizes of 10 nm or below. Silicon and germanium both display size-tunable optical and electronic properties, and are widely used in various devices, so a nanoscale semiconductor framework with features between 2-10 nm could be advantageous. Although there have been a few examples of silicon and germanium nanostructures reported in the literature, at the size range of interest to this work many conventional deposition techniques have mass transport or kinetic limitations that prevent them from fully infiltrating the small, tortuous pores present in mesoporous and microporous materials without the formation of voids or nanoparticles. To address this challenge, high pressure chemical vapor deposition (HPCVD) was developed in the Badding lab and was shown to be capable of completely infiltrating nanoporous templates. Using this process, a structure can be obtained that is periodic, with 3-D order and connectivity derived from the original template. Germanium was deposited within the empty pore networks of KIT-5 mesoporous silica using HPCVD. Characterization by small angle X-ray scattering, wide angle X-ray scattering, and transmission electron microscopy confirm that the resulting nanostructured germanium has well-defined ordered features that are 5 nm in size. To date, this is the smallest template material that has been successfully infiltrated using HPCVD. Additional composite materials were prepared by functionalizing mesoporous carbons and metal-organic frameworks with small amounts of silicon or germanium. A new sample holder was also designed and utilized to scale up processes, facilitating the use of characterization techniques that require larger amounts of material. These advances expand the capabilities of HPCVD by increasing both the potential template materials that can be used and the amount of material that can be synthesized with this technique. This dissertation expands the HPCVD technique for use with microporous and mesoporous templates. Overall, mesoporous materials were the most suitable given their larger pore sizes (2 -- 50 nm). Mesoporous silicas were fully infiltrated, resulting in a nanostructured semiconductor with a high degree of order and consistent feature sizes. A small amount of semiconductor was likely infiltrated within the smaller microporous (
Semiconductor Nanostructures
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Author :
language : en
Publisher:
Release Date : 2008
Semiconductor Nanostructures written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Electronic dissertations categories.
Traditional lithographic method of making microelectronic circuit is approaching the physical limit. Semiconductor nanostructures are possible candidates for building blocks of new generation electrical and optical circuit. In this project, my goal is to fabricate semiconductor-based nanostructures and investigate their structural, electrical and optical properties. For this, a chemical vapor deposition (CVD) system, based on the vapor-liquid-solid (VLS) mechanism, for growing semiconductor nanowires, specifically GaN nanowires has been designed and assembled. Using this CVD system, single crystal GaN wurtzite nanowires has been demonstrated on Ni catalysts deposited on sapphire substrates. The wires exhibit a vertical growth with non-uniform wire diameters. In order to control the wire diameter and spacing of the nanowire growth, nanoporous alumina templates has been used a mask to control catalyst deposition and pattern the substrate. Under such conditions, we demonstrated a new epitaxially grown GaN wire growth in the zing-blende type cubic crystal structure. This is in contrast to the vertically grown wurtzite structure which is typically obtained. We have studied the detailed structural properties (using scanning and transmission electron microscopy and atomic force microscopy) for both kinds of wires has been studied. Raman spectroscopy, photoluminescence, current-voltage measurements for the nanowires are studied and possible device applications such as in transistors are investigated in this thesis.
Nanostructured Titanium Dioxide In Photocatalysis
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Author : It-Meng Low
language : en
Publisher: CRC Press
Release Date : 2021-06-18
Nanostructured Titanium Dioxide In Photocatalysis written by It-Meng Low and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-06-18 with Technology & Engineering categories.
Titanium dioxide (TiO2) has drawn considerable attention as an attractive inorganic raw material for various applications due to its inexpensiveness, nontoxic nature, stability, and excellent photocatalytic activity. Photocatalysis is one of the most promising route for sustainable chemistry of the 21st century. It can contribute to solving environmental, global energy, and chemical problems, as well as to the sustainable production of commodities in the near future. This book presents the fundamentals of photocatalysis in nanostructured TiO2 and describes the factors affecting the photocatalytic activity, design, and synthesis of various forms of nanostructured TiO2. It highlights the use of ion-doping and inert-atmosphere annealing to extend the light-absorption range of photocatalysts and reduce recombination between electrons and holes. It discusses numerous applications in the fields of energy and environment, such as water purification, gas sensing, storage and delivery, and energy generation. The book is an invaluable resource and useful guide for a broad readership in various fields of catalysis, materials science, environment, and energy.
High Pressure Confined Chemical Vapor Deposition Of Electronic Metalattices And Semiconductors In Extreme Geometries
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Author : Hiu Cheng
language : en
Publisher:
Release Date : 2018
High Pressure Confined Chemical Vapor Deposition Of Electronic Metalattices And Semiconductors In Extreme Geometries written by Hiu Cheng and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
New materials design with tunable physical properties has been the dream of many. Well-ordered nanometer-scale materials with 3-dimensional structural order could interact with electronic, magnetic and vibrational degrees of freedom of materials to engineer new properties into well developed semiconductor platforms such as silicon and germanium. The synthetic realization of such structures, which we define as metalattices with periodicity from 1 60 nm highlights the possibility of continuous tuning of properties. Ordered, electrically continuous 3D structural modulations of quantum confinement and interfacial physics could lead to new physical phenomena with new electrical, thermal, magnetic and acoustic responses.This dissertation focus on the synthesis of electronic metalattice structures and other functional materials using high pressure confined chemical vapor deposition (HPcCVD). The synthetic route presented here allows for control over metalattices periodicity, size, symmetry, chemical composition, topology and surface chemistries. The strategy used to fabricate metalattices is to deposit semiconductors such as silicon, germanium and zinc selenide into the pores of nano-templates using HPcCVD. High pressure (up to 70 MPa), allows for void free infiltration of high quality electronic grade materials into nano-pores. A series of templates, including silica colloidal crystals of different sizes, zeolites, mesoporous silica and metal-organic frameworks were examined for tuning periodicities, symmetries and sizes of metalattices. The first silicon and germanium metalattices with 14 nm, 30 nm and 60 nm were made possible with HPcCVD infiltration. A variety of characterization techniques, including Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and x-ray diffraction were used to assess the as deposited materials quality. Post processing methods were developed to remove the nano-template and prepared the sample for advanced characterization and to increase the crystallinity of the synthesized metalattices.
Nanoparticles And Nanostructured Films
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Author : Janos H. Fendler
language : en
Publisher: John Wiley & Sons
Release Date : 2008-11-21
Nanoparticles And Nanostructured Films written by Janos H. Fendler and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-11-21 with Science categories.
In this concise handbook leading experts give a broad overview of the latest developments in this emerging and fascinating field of nano-sized materials. Coverage includes new techniques for the synthesis of nanoparticles as well as an in-depth treatment of their characterization and chemical and physical properties. The future applications of these advanced materials are also discussed. The wealth of information included makes this an invaluable guide for graduate students as well as scientists in materials science, chemistry or physics - looking for a comprehensive treatment of the topic.
Handbook Of Humidity Measurement Volume 3
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Author : Ghenadii Korotcenkov
language : en
Publisher: CRC Press
Release Date : 2020-01-24
Handbook Of Humidity Measurement Volume 3 written by Ghenadii Korotcenkov and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-01-24 with Science categories.
Because of unique water properties, humidity affects materials and many living organisms, including humans. Humidity control is important in various fields, from production management to creating a comfortable living environment. The range of materials that can be used in the development of humidity sensors is very broad, and the third volume of the Handbook of Humidity Measurement offers an analysis on various humidity-sensitive materials and sensor technologies used in the fabrication of humidity sensors and methods acceptable for their testing. Additional features include: numerous strategies for the fabrication and characterization of humidity-sensitive materials and sensing structures used in sensor applications, methods and properties to develop smaller, cheaper, more robust, and accurate devices with better sensitivity and stability, a guide to sensor selection and an overview of the humidity sensor market, and new technology solutions for integration, miniaturization, and specificity of the humidity sensor calibration. Handbook of Humidity Measurement, Volume 3: Sensing Materials and Technologies provides valuable information for practicing engineers, measurement experts, laboratory technicians, project managers in industries and national laboratories, and university students and professors interested in solutions to humidity measurement tasks. Despite the fact that this book is devoted to the humidity sensors, it can be used as a basis for understanding fundamentals of any gas sensor operation and development.
On Delveloping Novel Energy Related Nanostructured Matericals By Atomic Layer Depositon
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Author : Xiangbo Meng
language : en
Publisher:
Release Date : 2011
On Delveloping Novel Energy Related Nanostructured Matericals By Atomic Layer Depositon written by Xiangbo Meng and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
This thesis presents the fabrication of a series of novel nanostructured materials using atomic layer deposition (ALD). In contrast to traditional methods including chemical vapor deposition (CVD), physical vapor deposition (PVD), and solution-based processes, ALD benefits the synthesis processes of nanostructures with many unrivalled advantages such as atomic-scale control, low temperature, excellent uniformity and conformality. Depending on the employed precursors, substrates, and temperatures, the ALD processes exhibited different characteristics. In particular, ALD has capabilities in fine-tuning compositions and structural phases. In return, the synthesis and the resultant nanostructured materials show many novelties This thesis covers ALD processes of four different metal oxides including iron oxide, tin oxide, titanium oxide, and lithium titanium oxide. Four different substrates were used in the aforementioned ALD processes, i.e., undoped carbon nanotubes (CNTs), nitrogen doped CNTs (N-CNTs), porous templates of anodic aluminum oxide (AAO), and graphene nanosheets (GNS). In practice, owing to their distinguished properties and structural characters, the substrates contributed to various novel nanostructures including nanotubes, coaxial core-shell nanotubes, and three-dimensional (3D) architectures. In addition, the surface chemistry of the substrates and their interactions with ALD precursors also were considered. The ALD process of iron oxide (ALD-Fe2O3) was the first one studied and it was fulfilled on both undoped CNTs and N-CNTs by using ferrocene and oxygen as precursors. It was found that N-CNTs are better than undoped CNTs for the ALD-Fe2O3, for they provide reactive sites directly due to their inherent properties. In contrast, undoped CNTs need pretreatment via covalent acid oxidation or non-covalent modification to create reactive sites before the ALD-Fe2O3 could proceed on their surface. This work resulted in different CNT-Fe2O3 core-shell structures with controlled growth of crystalline -Fe2O3 Another metal oxide, tin dioxide (SnO2) was performed using tin chloride (SnCl4) and water as ALD precursors. It was synthesized into different nanostructures based on NCNTs, AAO, and GNS. The work on N-CNTs disclosed that the ALD-SnO2 is favored by doped nitrogen atoms but the effects of different nitrogen-doping configurations vary with growth temperatures. In comparison, the ALD-SnO2 on AAO and GNS mainly relies on hydroxyl groups. A common finding from the studies is that growth temperatures influence the resultant SnO2, leading to amorphous, crystalline phase, or the mixtures of the aforementioned two. In addition, the cyclic nature of ALD contributes to controlled growth of SnO2. Based on the results from the ALD-SnO2 on AAO, it was concluded that the ALD-SnO2 experience three different growth modes with temperature, i.e., layer-by-layer, layer-by-particle, and evolutionary particles. The layers are in amorphous phase while the particles are in crystalline rutile phase. The aforementioned understandings on ALD-SnO2 led to pure SnO2 nanotubes based on AAO, CNT-SnO2 core-shell coaxial nanotubes, and GNS-based SnO2 3D architectures with controlled growth and structural phases. The third metal oxide, titanium dioxide (TiO2) was deposited using titanium isopropoxide (TTIP) and water as ALD precursors. It was found that the ALD-TiO2 is tunable from amorphous to crystalline anatase phase with temperature while the resultant deposition is controllable from nanoparticles to nanofilms as well. Based on different substrate, i.e., AAO, acid-pretreated CNTs, and GNS, TiO2 was fabricated with different nanostructures including nanotubes, core-shell coaxial nanotubes, and 3D architectures. In particular, the resultant nanostructures are distinguished with controlled phases and morphologies of TiO2. Different from the above binary metal oxides, the last metal oxide, lithium titanium oxide (Li4Ti5O12, LTO) is a ternary compound. The route for ALD-LTO is based on combining and tuning two sub-ALD systems. One sub-ALD system is for TiO2 using TTIP and water, and another sub-ALD system is for lithium-containing films using lithium tert-butoxide (LTB) and water as precursors. It was revealed that, through suitably matching the ratios of the two sub-ALD systems and annealing the resultant films, LTO is successfully synthesized on N-CNTs. However, this pioneering work shows a bit rutile TiO2 with LTO, and thus further effort is needed in future work.
Environmental Chemical And Medical Sensors
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Author : Shantanu Bhattacharya
language : en
Publisher: Springer
Release Date : 2017-12-22
Environmental Chemical And Medical Sensors written by Shantanu Bhattacharya and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-12-22 with Technology & Engineering categories.
This book covers the fundamentals of sensor technologies as well as the recent research for the development of environmental, chemical and medical sensor technologies. Chapters include current research on microflow cytometry, microfluidic devices, colorimetric sensors, and the development of low-cost optical densitometric sensors and paper based analytical devices for environmental and biomedical applications. Special focus has been given to nanotechnology and nanostructures- their fabrication, uses and utility in different fields of research such as for the design of tools for medical diagnostics, therapeutics, as well as for detection and estimation of pollutant levels in water and air quality monitoring. This book is intended as a resource for researchers working in the field of sensor development across the world.
Journal Of Nanoscience And Nanotechnology
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Author :
language : en
Publisher:
Release Date : 2005
Journal Of Nanoscience And Nanotechnology written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Nanoscience categories.
Nanowires
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Author : Simas Rackauskas
language : en
Publisher: BoD – Books on Demand
Release Date : 2019-04-10
Nanowires written by Simas Rackauskas and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-04-10 with Technology & Engineering categories.
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.