Nanostructured ferroelectric materials
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Date
2012-12
Authors
Varghese, Justin M.
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Publisher
University College Cork
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Abstract
Nanostructured materials are central to the evolution of future electronics and
information technologies. Ferroelectrics have already been established as a
dominant branch in the electronics sector because of their diverse application range
such as ferroelectric memories, ferroelectric tunnel junctions, etc. The on-going
dimensional downscaling of materials to allow packing of increased numbers of
components onto integrated circuits provides the momentum for the evolution of
nanostructured ferroelectric materials and devices. Nanoscaling of ferroelectric
materials can result in a modification of their functionality, such as phase transition
temperature or Curie temperature (TC), domain dynamics, dielectric constant,
coercive field, spontaneous polarisation and piezoelectric response. Furthermore,
nanoscaling can be used to form high density arrays of monodomain ferroelectric
nanostructures, which is desirable for the miniaturisation of memory devices.
This thesis details the use of various types of nanostructuring approaches to fabricate
arrays of ferroelectric nanostructures, particularly non-oxide based systems. The
introductory chapter reviews some exemplary research breakthroughs in the
synthesis, characterisation and applications of nanoscale ferroelectric materials over
the last decade, with priority given to novel synthetic strategies. Chapter 2 provides
an overview of the experimental methods and characterisation tools used to produce
and probe the properties of nanostructured antimony sulphide (Sb2S3), antimony
sulpho iodide (SbSI) and lead titanate zirconate (PZT). In particular, Chapter 2
details the general principles of piezoresponse microscopy (PFM). Chapter 3
highlights the fabrication of arrays of Sb2S3 nanowires with variable diameters using
newly developed solventless template-based approach. A detailed account of
domain imaging and polarisation switching of these nanowire arrays is also
provided. Chapter 4 details the preparation of vertically aligned arrays of SbSI
nanorods and nanowires using a surface-roughness assisted vapour-phase deposition
method. The qualitative and quantitative nanoscale ferroelectric properties of these
nanostructures are also discussed. Chapter 5 highlights the fabrication of highly
ordered arrays of PZT nanodots using block copolymer self-assembled templates and
their ferroelectric characterisation using PFM. Chapter 6 summarises the
conclusions drawn from the results reported in chapters 3, 4 and 5 and the future
work.
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Keywords
Ferroelectric , Nanostructured , PFM , Template , AAD
Citation
Varghese, J. D. 2012. Nanostructured ferroelectric materials. PhD Thesis, University College Cork.