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Scanning probe microscopy (SPM) is unique among the imaging
techniques in which it provides three-dimensional (3-D) real-space
images and among surface analysis techniques in which it allows
spatially localized measurements of structure and properties. Under
optimum conditions, subatomic spatial resolution is achieved. The
development given has not been only because of its ability to obtain
topographic and structural images of the surface at micro and nano
scale, but also for the possibility of performing analysis of
superficial properties such as local adhesion properties, chemical
heterogeneity, and local mechanical properties [1]. The SPM has
different variations depending on the interaction between the tip and
the sample surface, such as AFM, which has the ability of showing
topographic characteristics at atomic scale, LFM, which measures local
friction differences, FMM and PDM that measure differences of local
elasticity. The instrument counts with the spectroscopy mode and with
this it is possible to obtain Force — distance (F-d) curves that give
information about the local elastic properties of the sample surface. In
this work, TiN and ZrN thin films grown by the PAPVD by pulsed arc
technique were studied, using the AFM, LFM, FMM, PDM and spectroscopy F
vs. d techniques.
Silicon based devices are expected to achieve the limit of possible
downscaling in 10 to 15 years. Thus, the search of new materials to
construct smaller, faster and more energy efficient devices has been a
very active research area. Carbon nanotubes (CNTs) are very good
candidates to construct nanoelectronic and nanophotonic devices [1,2,3]
due to unique physical properties, such as its metallic or
semiconducting characteristics depending only its diameter and chirality
[4,5] and capability of caring high current densities (up to 1010A/cm2).
In this work we develop nanofabrication techniques of single-walled
carbon nanotubes (SWNTs) based devices using a combination of electron
beam and optical lithography with Atomic Force Microscopy (AFM). We used
both CVD-grown nanotubes [6] and HipCO-NTs [7] suspended on aqueous
solution and deposited on the substrate. Atomic Force Microscopy (AFM)
in tapping mode (Multimode Nanoscope IV, Digital Instruments) was used
to CVD sample characterization, study of CNT deposition and to localize
and index the nanotubes on substrate using lithography patterns as
references, making possible to selectively construct metallic contacts
on the CNTs.
Stable and defect-free films are required for many technological
applications, while controlled dewetting processes are important for
producing thin film microstructuring for microelectronics, optical
devices and biochip technology. In this work, we study the dewetting
features formed by drying an aqueous solution of a charged polymer
deposited on a mica substrate. A rich variety of morphologies can be
formed, including holes, polygonal networks, droplets and elongated
structures. The dewetting behavior depends on film thickness and on the
charge density on the polymer that can be controlled by surfactant
addition. The various nanoscale morphological patterns that are formed
may be applied as a potential method for surface nanostructuring.
The use of ultrathin polymer films as sensoactive layers in chemical
sensors has received great interest in recent years due to many
advantages such as the wide choice of polymeric system (polymer types
and/or combination, dopants in conducting polymers, etc), and the
possibility of tailoring the properties of these films in terms of
sensitivity and selectivity by an efficient control of the film
formation process [1]. Among the techniques used for ultrathin films
formation, self-assembly (SA) offers several advantages since the
substrate can take any form and size, deposition time is independent of
the substrate area, there are no requirements for additional equipments
and/or clean rooms, and a large quantity of materials can be assembled
into thin films [2-8].
Advances in High-Resolution Electron Microscopy: A Symposium Dedicated to the Memory of John Maxwell Cowley
Tin oxide (TO) or fluorine doped tin oxide (FTO) has been frequently
used as a transparent electrode in our organic opto-electronic devices
[1-3]. In general, these devices are fabricated in a sandwich structure
where an organic thin layer (approx. 100nm thick) stays between two
conducting electrodes, TO or FTO and Al. Due to higher conductivity FTO
is normally our choice. The morphology of the electrodes influences the
morphology of the organic layer, mainly when the deposition of the
organic layer is done electrochemically.
Call for nomination of individuals to be considered for major awards
by the Microscopy Society of America. Awards include Distinguished Scientist
awards, the Burton Medal, Outstanding Technologist awards, the Morton D Maser
Distinguished Service Award, and MSA citations.
Polymer blends are of increasing interest in the field of surface
technology because they can be used to change or tailor the properties
of surfaces for special application. In most cases not only the chemical
nature of the components is important for the physical properties of the
blend but also the components distribution on the blend surface. This
distribution is strongly dependent on the adsorption energy of the
polymers onto the substrate. According to the Flory-Huggins theory, the
criterion for polymer miscibility in blends is that the average
interaction parameter for a binary mixture of polymers, 12, must be less
than a critical value cri, which is calculated from weight-average
degrees of polymerization of the two polymers [1]. This parameter also
describes the difference of the interaction energies between similar and
different monomers. During the spin coating process the system tries to
reach a state of low energy, indicating that the substrate surface and
the vapor phase influence the wetting and dewetting of the substrate by
the resulting polymer films. However, one should notice that spin-coated
film structure may not correspond to the equilibrium one due to the
rapid solvent evaporation during the spin coating process and to solvent
effects [2].