Union between top-down and bottom-up assembly is inevitable when scaling down physical, chemical, and biological sensors and probes. Current sensor/probe-based technologies are firmly founded on top-down manufacturing, with limitations in cost of production, manufacturing methods, and material constraints. As an alternative to such limitations, contemporary synthesis techniques for one-dimensional nanostructures have been combined with established methods of micro-fabrication for the development of novel tools and techniques for nanotechnology. More specifically, this dissertation is a systematic study of the synthesis and characterization of ZnO nanostructures for piezoelectric applications. Within this study the following goals have been achieved: (1) rational design and control of a diversity of novel ZnO nanostructures, (2) improved understanding of polar-surface-dominated (PSD) phenomena among Wurtzite crystal structures, (3) confirmation of Tasker's Rule via the synthesis, characterization, and modeling of polar-surface-dominated nanostructures, (4) measurement of the surface-charge density for real polar surfaces of ZnO, (5) confirmation of the electrostatic polar-charge model used to describe polar-surface-dominated phenomena, (6) dispersion of ZnO nanobelts onto the selective layers of surface acoustic wave (SAW) devices for gas sensing applications, (7) manipulation of ZnO nanostructures using an atomic force microscope (AFM) for the development of piezoelectric devices, (8) fabrication of bulk acoustic resonator (BAR) and film bulk acoustic resonator (FBAR) devices based on the integrity of individual ZnO belts, (9) electrical characterization of a ZnO belt BAR device, (10) prediction and confirmation of the electrical response from a BAR device using a one-dimensional Krimholt-Leedom-Matthaei (KLM) model, and (11) development of a finite element model (FEM) to accurately predict the electrical response from ZnO belt BAR and FBAR devices in 3D.

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.

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

As wide band semiconductors with rich morphologies and interesting electric, optical, mechanical and piezoelectric properties, ZnO nanostructures have great potential in applications, such as strain sensors, UV detectors, blue LED, nano generators, and biosensors. ZnO Nanostructures: Fabrication and Applications covers the controllable synthesis and property optimization of ZnO nanostructures through to the preparation and performance of nanodevices for various applications. The book also includes recent progress in property modulation of ZnO nanomaterials and new types of devices as well as the latest research on self-powered devices and performance modulation of ZnO nanodevices by multi-field coupled effects. Authored by a leading researcher working within the field, this volume is applicable for those working in nanostructure fabrication and device application in industry and academia and is appropriate from advanced undergraduate level upwards.

Over the past decade, ZnO as an important II-VI semiconductor has attracted much attention within the scientific community over the world owing to its numerous unique and prosperous properties. This material, considered as a “future material”, especially in nanostructural format, has aroused many interesting research works due to its large range of applications in electronics, photonics, acoustics, energy and sensing. The bio-compatibility, piezoelectricity & low cost fabrication make ZnO nanostructure a very promising material for energy harvesting.

This book is a printed edition of the Special Issue "Zinc Oxide Nanostructures: Synthesis and Characterization" that was published in Materials