Mixed monolayers of dimyristoylphosphatidylcholine (DMPC) and quercetin palmitate (QP) in a molar ratio of 25/75 have been transferred on mica and oxygen plasma cleaned silicon by the Langmuir-Blodgett (LB) technique at different subphase temperatures. Scanning Force Microscopy (SFM) in height, phase and lateral force modes has been employed to investigate the structural and mechanical features at nanoscopic level of these samples. Although the two molecules show a wide range of miscibility at 37 °C, they give rise to phase separation at 10 °C. This last system provides a new example of nanometric scale self-organization. In particular spiral shaped domains rising from the wrapping-up of nanoscopic fiber-like structures have been observed. The high resolution achieved by the use of the dynamic scanning force microscopy operating in the net attractive regime allow to visualize characteristic nanoscopic rupture points along the supramolecular fibers. High mass resolution Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) spectra showed DMPC- as well as QP-related peaks. The ToF-SIMS spectra from the nanostructured samples (10 °C) have been compared with those from the homogeneous ones (37 °C). The phase separated samples provides interesting secondary ions that highlight the QP supramolecular condensation within the fiber-like structures.

We have performed nanoindentations using the tip of an AFM cantilever. Experiments have been made on a freshly etched hydrogen terminated Silicon (111) surface, yielding penetrations of less than 1 nm so that the onset of the plastic region(or yield threshold) determination have been carefully investigated. Furthermore, other nanomechanical properties such as hardness have been also investigated. The energy involved in such indentation processes where a nanometric deformation of the surface takes place, has been for the first time calculated by calibration against a non deformable surface, and a correlation with the atomic structure of the indented single crystal is inferred.

In this study, we have demonstrated successful site-specific cross-sectioning of carbon-nanotube - metal junctions which provided samples suitable for high resolution transmission electron microscopy and electron energy loss spectroscopy. For the cross-sectioning, we have suggested a modified technique based on combination of the Focused Ion Beam (FIB) lift-out and the conventional Ar+ ion milling techniques. Electron-transparent cross-sections of multiwall carbon nanotubes showing no significant surface amorphization or Ga contamination (typical artifacts of conventional FIB lift-out technique) were obtained. High-resolution transmission electron microscopy and electron energy loss spectroscopy of a multi-wall carbon nanotube cross-section have been carried out.

Metallic nanowires represent very interesting systems due to new phenomena such as quantum conductance and unexpected long interatomic distances attaining 0.3–0.5 nm. These large distances represent a challenge for physical interpretation. In this work we present experimental data from transmission electron microscopy and results from ab initio density functional calculations for suspended gold chains. We show that large distances as 0.5 nm can be easily explained by the presence of carbon atoms as contaminants, while distances ranging from 0.29 up to 0.36 nm might be explained as resulting of a mixture of clean stressed and contaminated linear chains.

Scanning capacitance force microscopy is used to localise Sn nanometer sized structures embedded in a silicon oxide thin film. The capacitance variation occurring between probe and sample in presence of a metallic cluster modifies the oscillation amplitude of the AFM probe at twice the frequency of the applied voltage. The extreme localisation of the interaction due to the small geometries involved allows a lateral resolution of few nm. Issues related to the contrast mechanism are discussed with the support 2D finite element calculation of the electric field distribution between probe and sample.

We demonstrate Magnetic Force Microscopy (MFM) imaging, at room temperature in air, of a 0.25mA DC current path in a 140nm-wide gold nanowire. The nanowire was created by focused ion beam milling of a 12μm wide Cr/Au line of 20nm/110nm Cr/Au thickness. Iterative fitting of the MFM data to an idealized model of the structure yielded a nanowire resistivity a factor of 3.5 higher than that of a control Cr/Au region which was unaffected by the ion beam processing. MFM imaging of an ion-implant patterned line shows current deflection around the implant region.

In this paper, we describe confocal optoelectronic holography microscopy (COEHM) technique specifically being developed for characterizing the shape of MEMS and microelectronics. This is particularly important because shape is directly related to the functionality, performance, and integrity of the microstructures of interest. A specific feature of COEHM is that it allows characterization of high aspect ratio MEMS and microelectronics. Representative applications demonstrating the capabilities of COEHM are presented. It is shown that measurement resolution is highly dependent on the numerical aperture (NA) of the optical components comprising COEHM and on the quality of image digitization. By utilizing optical components characterized by a magnification factor of 50x and a NA of 0.45, measurement resolution of 25 nm is achieved. The resolution is increased to 8 nm when utilizing optical components characterized by a magnification factor of 100x and a NA of 0.73.

We have constructed an advanced electric probing system, which is a triple-probe atomic force microscope (T-AFM). The T-AFM consists of “Nanotweezers” and an AFM with a carbon nanotube probe. Using this system, we fabricated a single-walled carbon nanotubes (SWNTs)/deoxyribonucleic acid (DNA) three-terminal device and measured the current-voltage (I-V) curves of this device. In this three-terminal device, DNA strands were entangled with the SWNT bundle, and behaved as a gate-insulator-layer. This three-terminal device worked as a metal-insulator-semiconductor field effect transistor (MIS-FET) with depletion switching behavior.

Carbon nanotubes have the potential of being used as interconnects and active semiconducting material in future electronic circuits. It is necessary to study such nano-scale circuits with probes that can make measurements with molecular precision. We describe results using two nanoprobe techniques, namely scanning surface potential microscopy (SSPM), and conductive tip atomic force microscopy (CT-AFM), in the investigation of electrical properties of nanotube circuits. Vertical arrays of multi-walled nanotubes, grown in a porous alumina template with a metal back contact were analyzed. Current mapping confirmed that the nanotubes were electrically connected to the back contact. Isolated single-walled nanotube bundles deposited on an oxidized silicon wafer, and contacted electrically through chromium electrodes were also studied. Contact potential differences between the metal and nanotubes, and the current in some connected nanotubes were measured. Measurements of contact potential with different metals, and the nature of microscopic transport is crucial. Contact potential measurements can also provide fast and reliable characterization of junctions between metallic and semiconducting nanotubes and metals electrodes.

Degradation due to electron beam irradiation is a significant problem for ZnS based phosphors, particularly for flat panel displays. In this study, ZnS:Ag phosphor particles were coated by nanoparticles of ZnO:Al by pulsed laser deposition (PLD), to suppress the cathodoluminescence (CL) degradation process under electron bombardment at 15 k V. The pressure of the vacuum chamber and the deposition time were changed to control the morphology of the coating, i.e. thickness, continuity, and uniformity. CL degradation of the phosphors was slowed down for all cases by the nanocoating. The relationship between the CL degradation and the morphology of the coating material was examined by an SEM combined with a simultaneous CL measurement device. Degradation mechanisms were elucidated in terms of the morphology of the coating material and the change in the surface atomic species during irradiation of the electron beam.

Interfaces, contacts, and homo- or hetero-junctions are critical components in nanometer dynamic random access memory (DRAM) semiconductor devices. With shrinkage in device dimensions, interfacial analysis by TEM becomes more and more challenging, especially in the case of investigating failure mechanisms for nanoscale FRACTURED INTERFACES where electronic signatures found to be open. In this article, fractured interfaces at several C1-type contacts (a path between a Bitline and a Metal 1 interconnector) in a deep-subquarter-micron 256Mbit DRAM device were investigated by a JEOL 2010F analytical transmission electron microscope (TEM) with field-emission gun (FEG) running at 200KV. Considering the difficulty to exactly focus the fractured nano-scale interfaces at sufficiently high magnifications, high-resolution TEM (HR-TEM) and analytical scanning transmission electron microscopy (STEM) coupled with x-ray energy dispersive spectroscopy (XEDS) elemental linescan techniques were employed to provide supplemental information from difference prospects. An in-depth understanding for the nanoscale interfacial fracture mechanisms was established, and a simple model is initiated accordingly.

The primary deflection due to the chemical reaction between the analyte molecules and the receptor coating, which produces surface stresses on the receptor side is analyzed. The resonance frequency of microcantilevers is very sensitive to the properties of the microcantilever surface. Biosensing experiments based on resonance frequency shift are presented, which show that the results strongly depend on the interaction of specific analyte molecules with the receptor surface.

While self-assembled monolayer (SAM) systems have been intensively investigated since the seminal work of Nuzzo and others in the later 1980s, the detailed nature of the interactions between thiol and gold in terms of surface bonding and ligand motion, a central theme crucial for any further advancements in the field of SAMs, is still elusive and subject to controversy. Nuclear magnetic resonance (NMR) spectroscopy, a canonical technique of chemistry and physics, has the unique ability of providing insightful chemical bonding and ligand motional information. Recent advances in wet chemistry in terms of synthesizing alkanethiol-protected, very stable and almost monodispersed, gold nanoparticles, due to Schriffin and co-workers, enable this feature of NMR to be harnessed in the study of thiol-metal bonding and ligand motions on gold surfaces. Here, we report a detailed 13C NMR shift and relaxation investigation of monolayer-protected gold nanoparticles as a function of metal particle size, by using selectively 13C1-labelled octanethiol. Several interesting results are obtained for the first time: as the gold particle size increases from ca. 1.5 to 4.0 nm, the 13C1 NMR shift moves down-field from ca. 39 to 50 ppm (with respect to TMS), the spin-lattice relaxation rate 1/T1 decreases, and the spin-spin relaxation rate 1/T2 increases. For a given particle size, the 1/T2 varies across the heterogeneously broadened line shape, being higher at the lower field, while there is no clear trend shown in 1/T1. All these results suggest that while particle tumbling may be the dominant spin-lattice relaxation mechanism, the physical properties of the metal core, i.e., more metallic vs. less metallic, are most probably the dominant factors influencing the 13C1 NMR shift and spin-spin relaxation. Now new doors are opened up for more detailed NMR investigations of metal-ligand interactions in SAM systems.

Oxide composites have been produced by means of mechanical milling and sintering. Such materials consist of magnetic particles embedded in an insulating oxide matrix, which can have application as magnetic wave absorbers. Different systems have been investigated including MgO-MgFe2O4, FeO-Fe3O4 and other more complex ferrites. Milling induces the formation of a solid solution of cations and oxygen. Depending on temperature and system, sintering can produce a particle dispersion or simply the starting of the corresponding phase transformation. Spark plasma sintering was performed between 773 and 1373 K in order to reduce both processing time and temperature. High resolution (HREM) and conventional transmission electron microscopy show that an spinodal decomposition takes place in the system FeO-Fe3O4 during transformation from the solid solution.

Generally the oxygen lattice is unique throughout the material but there is a distinctive distribution of cations giving rise to a particle dispersioGn having an spinel structure in a insulating matrix with a NaCl cubic structure.

We present very high-resolution thermal microscopy using the technique of thermoreflectance, a non-contact measurement of the temperature in and around active semiconductor devices. By measuring the local change in reflectivity and comparing to the optical index versus temperature for the interface materials, thermoreflectance can determine the local temperature distribution. Thermoreflectance allows us to work at wavelengths much smaller than those used in typical blackbody imaging, and thus the spatial resolution is significantly improved over that of traditional thermal microscopy. In our experimental setup, we have a confocal scanning optical microscope with a tunable laser, where reflected light is detected by a silicon photodiode in a heterodyne scheme. The sample consists of a 600 nm wide poly-silicon wire embedded in silicon dioxide on top of a silicon substrate. Varying the amount and temporal shape of the current through the poly-silicon wire, we generate a controlled thermal profile to test the imaging capability. Our preliminary results indicate sub-micron thermal resolution.

We demonstrate ultrafast dynamical imaging of surfaces using a scanning tunneling microscope with a low-temperature-grown GaAs tip photoexcited by 100-fs, 800-nm pulses. We detect picosecond transients on a coplanar stripline and demonstrate a temporal resolution (full-width at half maximum) of 1.7 ps. By dynamically imaging the stripline, we demonstrate that the local conductivity in the sample is reflected in the transient correlated current and that 20-nm spatial resolution is achievable for a 2 ps transient, correlated signal. We apply this technique of photoconductively-gated ultrafast scanning tunneling microscopy to study carrier dynamics in InAs/GaAs self-assembled quantum dot samples at T=300 K. The initial carrier relaxation proceeds via Auger carrier capture from the InAs wetting layer (WL) on a timescale of 1–2 ps, followed by recombination of carriers on a 900 ps timescale. Finally, we demonstrate junction-mixing ultrafast STM (JM-USTM) using picosecond voltage pulses propagating on a patterned metal-on-metal (Ti/Pt). Using JM-USTM we have achieved a spatio/temporal resolution of 1 nm/8 ps.

To investigate the role of grain boundaries and other growth related microstructure in manganite films, a scanning tunneling microscope is used to simultaneously probe surface topography and local potential distribution under current flow at nanometer level in films of epitaxial thin films of La0.7Ca0.3MnO3 deposited on single crystal SrTiO3 and NdGaO3 substrate by laser ablation. We have studied two types of films strained and strain relaxed. Thin (50nm) films (strained due to lattice mismatch between substrate and the film) show step growth (unit cell steps) and have very smooth surfaces. Relatively thicker films (strain relaxed, thickness 200nm) do not have these step growths and show rather smooth well connected grains. Charge transport in these films is not uniform on the nanometer level and is accompanied by potential jumps at the internal surfaces. In particular scattering from grain boundaries results in large variations in the local potential resulting in fields as high as 104-105V/cm located near the grain boundaries. We discuss the role of local strain and strain inhomogeneties in determining the current transport in these films and their resistance and magnetoresistivity. In this paper we attempt to correlate between bulk electronic properties with microscopic electronic conduction using scanning tunneling microscopy and scanning tunneling potentiometry.

The nanometer-scale plastic behavior of two low thermal expansion glasses (ULE® and Zerodur®) was determined through a combination of nanoindentation experiments and finite element modeling. The finite element models were then extended to investigate aspects of the performance of these materials as extreme ultraviolet lithography reticles.

Electrically active regions of nanocrystalline silicon (nc-Si) films as well as of a p-type crystalline silicon (c-Si) wafer have been investigated by using a scanning electron microscope/scanning tunneling microscope (SEM/STM) combined instrument. The nc-Si films were obtained by boron implantation of amorphous silicon layers with an average nanocrystal size of about 10 nm. STM current constant images reveal a cell structure in the nc-Si films which was also revealed in the STM remote electron beam induced current (REBIC) images with a resolution of up to 20 nm. The contrast in the STM-REBIC images indicate the existence of space charge regions at the boundaries. The influence of the thermal treatment on the cell structure was studied. For comparison, SEM-REBIC and STM-REBIC images from c-Si wafer were obtained.

In this paper we present results on transmission-energy and current-voltage curves for a Scanning Tunneling Microscopy probe in the presence of an atomic chain, operating in spectroscopy mode. We compare the results with independently calculated density of sates. Finally, we propose algorithms to process this experimental information to obtain chemical specificity and position of impurities in the chain.