A biomimetic approach is employed to deposit ceramic films on organic self-assembled monolayers (SAMs) coated substrates. Specifically, zirconia (ZrO2) films are grown in a zirconium sulfate precursor solution at near room temperatures (∼70°C). This process, directed by the nanoscale organic template, mimics the controlled nucleation and growth of the biominerals such as bones and teeth. The resultant zirconia films consist of nanosized particles (5-10 nm) that are precipitated out in a supersaturated precursor solution. Cross-sectional TEM and STEM works were performed to quantitatively analyze the film structure and chemistry, as well as interfacial region of the ceramic-SAM films. A stepwise deposition process was developed to avoid excessive formation of aggregation. Further, the dynamic nanoindentation testing was employed to assess the thickness and film-only intrinsic mechanical properties for direct comparison among the films processed with different processing parameters and microstructures. The films with finer particulate structure displayed higher intrinsic modulus than did those with coarser structure.

Fabrication strategies based on mechanisms of self-assembly are now widely being recognized as inevitable tools in nanotechnology. Self-organized construction of advanced materials and devices may be done starting with tailor made nanoparticles as building blocks. Multilayer thin films of gold, zinc sulphide and manganese doped zinc Sulfide nanoparticles were fabricated by a modified polyelectrolyte deposition process. A prerequisite to utilization of colloids for the fabrication of uniform layers is that they remain in suspension and resist unwanted agglomeration. The stability of colloids is generally achieved either by electrostatic stabilization, involving the creation of an electrical double layers arising from ions intentionally adsorbed on the surface of the particle and associated counter ions that surround the particle, or by steric hindrance that is achieved by the adsorption of macromolecules on the surface of the particles. The inherent necessity to introduce electrostatic or steric hindrance to avoid colloidal agglomeration was utilized to induce self-assembly of multilayers applying similar concept used for the layering of polyelectrolytes. Polyacrylic acid was used as the polyanion and chitosan as the polycation for the deposition process. Upto 100 layers of nanoparticles were constructed and films that were found to be stable and uniform over the substrate. The layer-by-layer deposition of multilayers of several different structures was prepared and devices showing resistive and capacitive electrical characteristics have been fabricated. The onset of electrical conduction in the resistive devices could be varied by introducing a dielectric interlayer between gold nanoparticles and by introducing a gold overlayer on the zinc sulphide nanoparticle devices.

In this paper we report the effects of strain on the electronic properties of single wall carbon nanotubes and its consequence on the resonant Raman cross section. A quantum interference effect has been predicted for the radial breathing mode spectra for metallic tubes. For metallic tubes, the lower and upper components of Eii resulting from the trigonal warping effect are affected differently and for low chiral angle they cross for some strain value. Near (at) the crossing point, the resonant Raman spectra profile exhibits a maximum (minimum) value due to a quantum interference in the Raman cross section. This Raman cross section interference effect was observed in Raman experiments carried out on isolated SWNTs. The Raman experiment performed on an isolated strained metallic SWNT supports our modeling predictions.

By combining scanning tunneling microscopy (STM) and the optical pump-probe technique using a femtosecond pulse laser, we have developed a new microscopy, shaken pulse-pair-excited STM (SPPX-STM), that enables us to observe the dynamics of electronic structures with the ultimate spatial and temporal resolutions.

Silicon nanowires (SiNWs) were fabricated directly from the Si source gas into pre-fabricated permanent nanochannel templates by our self-assembling “grow-in-place” approach. The size, shape, position, orientation, and number of the SiNWs can be precisely controlled by the pre-fabricated nanochannel templates. Our approach is environmentally benign and friendly since only the exact number of SiNWs needed was grown and the SiNWs were always confined in the nanochannel templates. In addition, the templates can be fabricated with built-in contacts and integrated into the final devices, providing contacts, interconnects, and passivation/encapsulation. We are developing a variety of built-in ohmic and rectifying contact structures and approaches for the “grow-in-place” methodology. Some initial results will be discussed here.

Self-assembled gadolinium silicide (GdSi2) nanostructures grown on Si(001) were studied by transmission electron microscopy (TEM) and scanning tunneling microscopy (STM). Cross-sectional TEM and plan-view TEM moiré fringe pattern analyses show that the GdSi2 nanostructures can be divided into two classes: elongated nanowires with hexagonal crystal structure and rectangular islands with orthorhombic or tetragonal crystal structure.

Development of UV blocking thin films with effective cut-off features with steep edges and high transmission in the visible and IR region have been developed. The unique optical, mechanical and chemical properties of silica and ceria nanocomposites with surface functional groups making them most promising candidate for applications in opto-electronic, automotive, and aeronautic industries. On the other hand, highly hydro and oleophobic films are being actively considered in optical, automotive and aeronautic industries to increase adhesion and scratch, abrasion resistance properties. In order to fill the gap, and fulfill the requirements to meet both ends, it could be proved that morphological changes in the nanometer range influences the water contact angles and their hystersis of low energy materials. Nanocomposite films of SiO2 and CeO2 with surface functionalisation with decafluorooctly-triethoxy silane itself forms nano-hemispheres (similar to lotus leaf) at and above 100°C favoring an increase in water contact angle from 122° (25°C) to 145°(400°C). The structural, optical, and hydrophobic properties have been examined by employing X-ray diffraction, UV-visible spectroscopy, contact angle techniques, respectively. The cut-off behavior of the deposited and annealed nanocomposite thin films have been tuned by varying different amounts of CeO2 in SiO2.

Highly selective and repeatable delamination of thermal oxide films from Si(100) substrates has been performed using single and multiple femtosecond laser pulses forming bubbles or blisters. By overlapping the bubbles laterally, tubes or capillaries can be formed with a range of volumes suitable for nanofluidics. By scanning the sample through the laser using an automated translation stage, patterns of tubes with arbitrary complexity can be formed, while the scan velocity can easily control the volume of the tubes. The production time for capillaries in this fashion is considerably less than with other lithographic techniques, while the proximity of the tubes to the underlying silicon substrate yields the possibility for integrated devices. The mechanism responsible for the delamination will be discussed and the optimal laser and sample translation conditions will be presented which provide the most uniform tubes. Atomic force microscopy and optical microscopy of capillaries with a range of volumes will be presented.

Long, straight self-assembled nanolines of Bismuth are used as an atomic-scale non-lithographic template for the deposition of different metals. The Bi nanolines are 15 Å wide and can grow to lengths exceeding 1μm, limited only by the substrate terraces. We describe the method of formation of these templates, and demonstrate strongly preferential adsorption of different metals. We observe both wetting behaviour, in which elongated metal islands form nanowires along the template, and nonwetting behaviour, in which arrays of metal clusters of uniform size are produced.

A nano-structured beta-gallia-rutile (BGR) substrate capable of binding DNA was synthesized. Beta-gallia groups diffuse into [001] single crystal rutile along {210}r planes, generating hexagonally shaped tunnel sites between the beta-gallia subunits (repeating ∼1 nm). The tunnel sites, approximately 2.5 Å in diameter, are preferred regions for cation incorporation. Divalent cations have been used previously to adsorb DNA to mica surfaces. For the BGR system, the site selectivity of the cations for tunnel sites could lead to controllable / tailor-able DNA adsorption. DNA buffers containing Cu (II), Fe (II), and Ni (II) cations were deposited on BGR substrates. The DNA adsorption was investigated with tapping mode atomic force microscopy (AFM) to determine the suitability of using BGR substrates as a means to self assemble DNA constructs for nano-electronic applications. At the concentrations tested, only solutions containing Ni (II) ions were capable of binding DNA sufficiently for AFM imaging; there was no evidence of site specific attachment.

There has been considerable interest in the properties of rare earth metal nanostructures grown epitaxially on Si(001) surfaces. The questions arises as to what extent the nanometer scale lateral dimensions (width and thickness) affect the material properties. We compare thin film Gd silicide samples with Gd nanostructures grown on Si(001) using high resolution transmission electron microscopy (HRTEM). The nanostructures have the same orthorhombic crystal structure as the thicker silicide films. Electron energy loss spectroscopy measurements from metallic Gd and the thin film silicides are also shown as references for similar measurements on the nanostructures.

The mechanical properties of Au nanowires under a uniaxial load are investigated by molecular-dynamics simulation. The modified embedded-atom method (MEAM) potential is employed to calculate the interactions between Au atoms. Ten kinds of model nanowires with different cross-sections and axis directions are prepaired. The structural dependence and size effect of the Young’s moduli of Au nanowires are discussed.

This paper discusses a kinetically-driven patterning scheme to marry top-down and bottom-up assembly of nanoparticle arrays. We explain how Ge atoms interact with different dielectric surfaces to either etch the surface or to accumulate and self assemble into nanocrystals during chemical vapor deposition. By exploiting the different reactivity of these dielectrics, the accumulation of adatoms is controlled and thus subsequent self assembly of nanocrystals is controlled. Scanning electron microscopy and atomic force microscopy are used to determine particle densities. We have achieved dense (>1011 cm-2) arrays of self-assembled Ge nanocrystals within ∼100 µm sized features (defined by optical lithography) with no Ge deposition on the adjacent SiO2 sacrificial mask region. Electron beam lithography was used to pattern smaller (100 µm to 500 nm) features in which to direct the self assembly. As features shrink below 10 µm, nanoparticle nucleation within the feature is sharply affected. Finally, diblock copolymers are used to pattern 20 nm features to template self assembly of nanoparticles at a scale useful for device applications.

We have explored the fabrication of conductive nanowires on different types of substrates by electrochemistry-assisted DPN (E-DPN) with an atomic force microscope. Various parameters of E-DPN were examined systematically including the effects of coating methods and the types of the tips on the electrodeposition behavior. It was found that a chemically-modified Si AFM tip is very suitable for E-DPN. Platinum and polyaniline nanowires with a line width of ca.100 nm to sub- 100 nm were prepared on the metallic (Au) and semiconducting (Si) surfaces. The parameters indispensable for E-DPN of metal and polymer nanowires on an insulating SiO2 surface will also be discussed.

A phase field model is developed to simulate the molecular motion and patterning under the combined actions of dipole moments, intermolecular forces, entropy, and external electric field. The study reveals self-alignment, pattern conformation and the possibility to reduce the domain sizes via a layer by layer approach.

Aqueous synthesis of glutamate functionalized single crystal gold nanoparticles was achieved by reducing a solution of chloroauric acid with monosodium glutamate. Highly uniform size distributions of the nanoparticles can be obtained by having an excess of monosodium glutamate in the starting solution. Similar to the conventional synthesis of gold nanoparticles by reduction of chloroauric acid with trisodium citrate, the obtained particle sizes were varied in the range of 14 – 25 nm without loosing the uniformity in its size distribution by varying the concentration of the reducing agent.

Here is reported, from the theoretical point of view, how a stressor layer included in a nanomesa can modify the growth process of a mismatched material : critical thickness for 2D-3D transition, and optimal location of nucleating dots by means of the induced stress field. This stress field depends on both design parameters and sign of the misfit between the stressor and the mesa material. This is exemplified by the case of InAs deposition on InP mesas which include an InGaAs stressor. A second case in which stress field plays a key role is the capping of dots on top of nanomesas . We investigate the case of Si capping of a system where one Ge dot covers the top of each mesa of a very dense array of Si nanomesas. Upon several basic assumptions, different capping processes are simulated, in order to predict the more stable one. We point out very different behaviors for pure Si capping or SiGe capping. How long it takes for recovering a flat surface strongly depends on the presence of a thin Ge surface layer.

New patterning schemes for a variety of applications including sensors and photonics are explored. We present here a comprehensive study of using focused ion beam (FIB) milling to modify surfaces over millimeter-scale areas with nano-patterns of dimensions down to 30 nm. A typical example of a pattern is 40 nm diameter × 40 nm depth wells with a 200 nm pitch. Typical sample materials are metals, but polymer patterning is possible. We have also evaluated the surface of the patterned materials to ensure there are no negative effects of these patterning schemes on the future device performance.

One area of particular effort recently is the use of colloidal particles as precursors in engineering new materials. Nevertheless, these particles are nearly always spheres. This places limitations on the structures that can be built, especially in making photonic-bandgap materials. Therefore, it is a great challenge to create new colloids with an original shape, i.e. different from the sphere, in a controllable manner.

We present here an original approach to create hybrid organic-inorganic colloidal particles with a perfect controlled shape. The synthetic route of these structures, which are composed of spherical silica spheres surrounded by a varying number of polystyrene beads, consists in the emulsion polymerization of styrene in presence of silica particles, which had been surface-modified by a coupling agent containing polymerizable groups.

The influence of the size of the silica particle and of the nature of the coupling agent on the resulting colloidal particles morphologies was carefully analyzed. We show in particular that the number of growing polystyrene beads varies homogeneously with the diameter of the mineral spheres. A main advantage of this technique is also that we can precisely control the reaction time, allowing us to tune the final morphology of the hybrid structures. These colloidal assemblies are original building blocks for the elaboration of new functional materials.

Analyzing the rolling behavior of micro-object is necessary for the realization of the micro-manipulation technique by mechanical-method. Thus in this paper, we obtain the rolling resistance of an isotropic elastic cylindrical micro-object in adhesive contact to a rigid surface.

In order to estimate the rolling resistance, we assume this adhesive contact to be the plane strain problem, and calculate the total energy of this system as the numerical function of the contact area using finite element method (FEM). The total energy of this system is defined as the sum of the next three terms: the elastic energy of the cylindrical micro-object, the interface energy within the contact area, and the mechanical potential energy that depends on the external moment applied to the cylindrical micro-object. A careful consideration of the energy balance of the system clarifies that the rolling resistance has the value of 0.1 [10-12Nm] for the polystyrene (where a work of adhesion = 0.1[N/m]) cylindrical micro-object with the radius and thickness. Hence, we establish the procedure of the calculation for the rolling resistance of the micro-object based on the principle of the energy balance by finite element method.