Conventional top-down lithographic processes approach their practical and theoretical limits at dimensional scales less than 100 nm. Alternative bottom-up methods are being investigated to build nanoscale architectures, including the use of biomolecules whose functional groups bind inorganic particles. In this study, the fabrication and alignment of microtubule-based nanowires are investigated. Microtubules (MT) are fibrous proteins found in nearly all eukaryotes. Our work was carried out using polymerized alpha- and beta-tubulins, which were cross-linked with glutaraldehyde to stabilize the protein structure. Ni coated microtubules were fabricated by reducing Ni2+ to Ni0 on Pd activated microtubule surface. Focus Ion Beam was used to write metal contacts on these Ni microtubule nanowires and DC conductivity values were measured. Au deposition on MT was performed by both electroless deposition and electrodeposition, by reducing HAuCl4 onto MT prebound with 2 nm Au colloids. Although most MTs exhibited discontinuous Au binding, a fraction of MTs were covered completely by Au. Preliminary electrical measurements for these materials are reported. Alignment of microtubules was also achieved by injecting MTs into microfluidic devices over amine-coated substrate surfaces. These biotemplating approaches are the first steps towards constructing more complicated 2D and 3D architectures.

Novel meso-/macroporous SiO2 monoliths have been reached by applying a nanotectonic pathway within a confined geometry, i.e. a non-static air-liquid foam patterning process. Final scaffolds are a very close transcription of the tailored periodic air-liquid foam template while coalesced silica particles are texturing the as-synthesized foam walls. The interconnected nanoparticles and associated void space between adjacent particles allow generating intrinsic mesopores, thereby defining hierarchically organized porous scaffolds. The good control over both the air-liquid foam’s water volume fraction and the bubble size allow a rational tuning of the macropore shape (diameter, Plateau border’s width). In contrast with previous study, closed-cell structures can be reached, while the opal like scaffold structure is maintained with thermal treatment, avoiding thus strong shrinkage associated to the sintering effect.

In this paper, we report clear evidence for the growth of carbon nanotubes and nanostructures at low substrate temperatures, using direct-current plasma-enhanced chemical vapour deposition. The catalyst particles are mounted on a titanium layer which acts as a thermal barrier, and allows for a larger temperature gradient between the Ni catalyst surface and the substrate. A simple thermodynamic simulation shows that the temperature differential between the substrate growth surface and the growth electrode is determined by the thickness of the titanium layer. This facilitates the growth of nanotubes, as opposed to nanofibres with herring-bone or amorphous structures. The growth properties are discussed as a function of the bias voltage and hydrocarbon concentration. The heating during growth provided solely by the plasma is below 400°C and is dependent on the process conditions and the electrode configuration in the growth chamber. These conditions need to be taken into account when comparing processes across different growth methods and instruments. The novel approach based on the use of a thermal barrier ensures the synthesis of carbon nanotubes at room temperature substrate conditions, which can be attained with a suitable cooling scheme.

Selectively grown carbon nanotubes (CNTs) and/or vertically aligned CNTs (VACNTs) on patterned metal electrodes have been prepared for applications to a novel electronic-measuring nano-probe. We propose newly a position-controlling method of CNTs by controlling not only a position of catalysts but also the thickness of metal underlayers for the catalysts. The selective growth of CNTs was achieved at edges of the metal pattern by thermal chemical vapor deposition. The width of selectively grown CNTs was minimized, about 2.6 µm. The width was about 80 times as small as that of the metal pattern. VACNTs were synthesized by a plasma enhanced CVD method in which the high electric field in a cathode dark space was applied to the substrates. The VACNTs grew up, however, all over the metal pattern.

Formation process of nanosized cap structures on a thermally treated 6H-SiC(000-1) substrate was investigated using atomic-resolution ultrahigh-vacuum scanning tunneling microscopy (UHV-STM). After formation of clusters of carobon particles 1-2 nanometer in diameter at 1150°C, these nanoparticles merged, forming nanosized cap structures. Hexagonal carbon networks, partly composed of pentagons, were clearly observed on the surface of the cap structures for a sample annealed above 1200°C. A model for the formation of carbon nanocaps on 6H-SiC(000-1) was proposed.

The hybrid assembly of inorganic nanomaterials upon chemical and biological bonding has occupied attentions to yield manifold optical and electromagnetic properties. Nanomaterials that can be virtually conjugated with any other nanomaterials by ligand-receptor / antigen-antibody reactions, polymer tethering, and DNA hybridization are of importance for fundamental comprehension of electronic process in nano-scale regime as well as for development of advanced sensing and imaging devices. Semiconducting nanoparticles(NPs)/ nanowires(NWs) like CdTe that have compatibly narrow range of strong photoluminescence (PL) with broad range of absorbance band stand in the spotlight of imaging and sensing materials. Optical effects in noble metallic NPs such as Au and Ag have been worth noticing due to localized surface plasmons. These optical modes lead to highly localized electromagnetic fields outside the particles that take advantage of the development of novel system such as surface enhanced Raman spectroscopy (SERS) and highly compacted optoelectronic devices and sensors. In particular, it is known that metallic NPs has stronger plasmon field than the surface of bulky metals, leading to potent interactions to adjacent materials in secured conjugated superstructures that induce non-linear optical properties. In this report, we review on a novel biological / polymeric inspired hybrid superstructures between semiconducting CdTe nanowires and Au or Ag nanoparticles. This superstructure demonstrates remarkable optical effects i.e., PL en-hancement of NWs, sensing application for temperature and solvents stemming from SERS-like collective interactions of NPs and NWs., and light harvest from Förster resonance energy tra-nsfer (FRET).

It is possible to make perfect conical carbon nanostructures fundamentally different from the other nanocarbon materials, notably buckyballs and nanotubes. Carbon cones are realized in five distinctly different forms. They consist of curved graphite sheets formed as open cones with one to five carbon pentagons at the tip with successively smaller cone angles, respectively. The nucleation and physics of nanocones has been relatively little explored until now. We present here the key facts and latest results on this “5’th form of carbon”.

Mask patterns for XY-type magnetic patterned media using phase separation of polystyrene-polymethylmethacrylate (PS-PMMA) block copolymer were fabricated. Parallelogram guides molded by the nanoimprint lithography controlled the PS-PMMA self-assembling pattern that formed in the guide area. 45nm-pitch defect-free PS-PMMA dot patterns were obtained within a 1μm × 1μm area by optimizing the PS-PMMA film thickness.

The liquid/solid interface provides an ideal environment to investigate self-assembly phenomena and scanning tunneling microscopy (STM) is the preferred methodology to probe the structure and the properties of physisorbed monolayers on the nanoscale. Physisorbed monolayers are of relevance in areas such as lubrication, patterning of surfaces on the nanoscale, and thin film based organic electronic devices, to name a few. It's important to gain insight in the factors which control the ordering of molecules at the liquid/solid interface in view of the targeted properties. STM provides detailed insight into the importance of molecule-substrate (epitaxy) and molecule-molecule interactions to direct the ordering of both achiral and chiral molecules on the atomically flat surface. The electronic properties of the self-assembled physisorbed molecules can be probed by taking advantage of the operation principle of STM, revealing spatially resolved intramolecular differences within these physisorbed molecules.

We have investigated the Sb surfactant-mediated growth of Ge on Si(113) over the temperature range from 500°C to 700°C. The surface morphology, film thickness, interface roughness and strain state of the films have been determined by the use of scanning electron microscopy, atomic force microscopy and grazing incidence x-ray diffraction. After growth at temperatures between 500°C and 600°C smooth Ge films have been observed, which show a partial strain relaxation. However, increasing the temperature to 700°C, a rough surface with a high density of three-dimensional islands has been found.

Single-walled carbon nanotubes (SWNTs) have been chemically attached with high density onto a patterned substrate. To form the SWNT pattern, the substrate was treated with acid-labile group protected amine, and an amine prepattern was formed using a photolithographic process with a polymeric photo acid generator. The SWNT monolayer pattern was then formed through the amidation reaction between the carboxylic acid groups of carboxylated SWNTs (ca-SWNTs) and the prepatterned amino groups. A high-density multilayer was fabricated via further repeated reaction between the carboxylic acid groups of the ca-SWNTs and the amino groups of the linker with the aid of a condensation agent. Scanning electron microscopy results show that the patterned SWNT films have uniform coverage with high surface density.

The Packing of submicrometer-sized polystyrene particle within micro-boxes; micrometer-sized squarely recessed pits, was achieved using silicon microfabricated substrates and a simple dipping and pulling-up process. A special phenomenon, cubic packing structures of the particles, was observed when using a micro-box substrate with a few times larger side-length than the particle diameters. Several particle packing structures within different sized micro-boxes were demonstrated, and the relationship between the particle packing structures and micro-box sizes were discussed.

The peak energy of photoluminescence (PL) from an undecylenic acid functionalized porous Si demonstrated a large PL red-shift (∼ 75 nm) during 2.5 hours of protein incubation in our previous work. [1] Here we present a similar in-situ PL study of surface functionalized planar Si (Si:COOH). The PL of Si:COOH exhibited a 5 nm red-shift in its peak frequency and an approximately 10% drop in its intensity after incubation in a protein solution. Vibrational spectroscopic characterization was carried out upon the Si:COOH sample for which we observed the PL red-shift. The infrared absorption spectra showed clear evidence of protein adsorption on Si:COOH. This correlation study between the PL peak energy and the vibrational spectrum provided strong evidence that the observed red-shift was due to the formation of semiconductor-protein (Si:COOH:BSA) complexes.

In this paper, we present examples of the use of photochemical metal organic deposition to form nanostructured metal oxide films. In the first example, we use two reactions with very different reaction rates to control the nanostructuring, utilizing tantalum (V) tetraethoxide acetylacetonate (as a thermally reactive source of tantalum oxide) and manganese (II) 2-ethylhexanoate (as a photochemically reactive source of manganese oxide). We prepare homogeneous precursor films of tantalum (V) tetraethoxide acetylacetonate and manganese (II) 2-ethylhexanoate and in the dark allow the tantalum complex to react forming tantalum oxide regions. The film is then exposed and the manganese complex is converted to a matrix surrounding the tantalum regions. The resultant structures are characterized by electron microscopy, energy dispersive X-ray spectroscopy and Auger spectroscopy. In the second example, we use two immiscible precursors, zirconium (IV) 2-ethylhexanoate and yttrium nitrate hexahydrate to form nanostructured precursor films. The nanostructuring of these films is apparent from SEM studies. Exposure of these films results in the formation of nanostructured films consisting of a zirconium oxide matrix with encapsulated yttrium oxide.

The fabrication of 3D nanostructures, which have tunable, sub-100 nm dimensions in all three directions, is a key issue of nanotechnology. Here we describe the integration of top-down nanoimprint lithography (NIL) and bottom-up layer-by-layer (LBL) assembly for the preparation of 3D hybrid nanostructures. NIL provided down to sub-100 nm poly(methylmethacrylate) (PMMA) structures. These were employed to fabricate patterned self-assembled monolayers of cyclodextrin (CD) host molecules on silicon oxide . The consecutive LBL assembly with adamantyl guest-functionalized dendrimers and CD-modified gold nanoparticles resulted in patterned multilayer structures with thicknesses of 3-30 nm. The x,y control by NIL and the z control by LBL assembly ultimately allowed the fabrication of circular structures with a radius of 25 nm and a thickness of 20 nm. The integration of the two methods has thus yielded a versatile 3D nanofabrication methodology comprising of 10-40 process steps.

We demonstrated a novel approach to fabricate a self-assembled array of energetic nanocomposites which undergo an exothermic reaction at high temperature. The nanocomposites are a mixture of fuel and oxidizer materials where one of the components (fuel or oxidizer) is in the form of an array of nanowires embedded in the other component (oxidizer or fuel) which is in the form of a thin film. Our fabrication approach allows for a very high packing density of the nanocomposites, precise control of oxidizer-fuel sizes at the nanoscale level and intimate mechanical contact between oxidizer and fuel. Such nanocomposites will have important applications in novel energetic devices, for example MEMS-based fuzes, nanoexplosives and in applications requiring light-weight, single-use energy sources.

Hollow foam spheres are needed for laser fusion experiments on the OMEGA laser facility at the University of Rochester as part of the demonstration of the feasibility of inertial confinement fusion. Previously polymer based foam and aerogel shells have been produced using resorcinol-formaldehyde (R/F) and divinylbenzene (DVB). In this paper we discuss the development of silica aerogel (SAG) shells. SAG may have the increased robustness, which is important in processing these laser targets. SAG shells were fabricated by the microencapsulation method using a triple orifice droplet generator. This technique allows for precise control of the shell diameter and wall thickness. Reduction of the aerogel gelation time is crucial to fabrication of intact shells with high yield. In addition, the proper choice of the components of the different phases of the microencapsulation process is essential for fabrication of intact SAG shells with proper sphericity and wall uniformity. The density of shells fabricated is approximately 100 mg/cc and the diameter ranges from 700–2000 μm, with a wall thickness of 50–200 μm. Development of a full density permeation barrier for retention of the fusion fuel will also be discussed.

The refractive index contrast in dielectric multilayer structures, optical resonators and photonic crystals is an important figure of merit, which creates a strong demand for high quality thin films with a very low refractive index. SiO2 nano-rod layers with low refractive indices n = 1.08, the lowest ever reported in thin-film materials, is grown by oblique-angle e-beam deposition of SiO2 with vapor incident angle 85 degree. Scanning electron micrographs reveal a highly porous columnar structure of the low-refractive-index (low-n) film. The gap between the SiO2 nano-rods is ≤50 nm, i.e. much smaller than the wavelength of visible light, and thus sufficiently small to make scattering very small. Optical micrographs of the low-n film deposited on a Si substrate reveal a uniform specular film with no apparent scattering. The unprecedented low index of the SiO2 nano-rod layer is confirmed by both ellipsometry measurements and thin film interference measurements. A single-pair distributed Bragg reflector (DBR) employing the SiO2 nano-rod layer is demonstrated to have enhanced reflectivity, showing the great potential of low-n films for applications in photonic structures and devices.

The bottom-up wet-chemical synthesis of inorganic materials provides tools for generating nanostructures from particles to one-dimensional structures, but these conventional chemical techniques usually offer little control over the deposition of metals or metal particles into nanosized ring structures although interesting properties and applications, e.g., Aharonov-Bohm rings are expected. Our results provide a straightforward and rapid wet-chemical synthesis to ring-like metal particle arrays. Applying appropriate conditions, tubulin dimers, proteins of 4-5 nm diameter and a length of 8 nm, self-assemble by specific recognitions capabilities into defined superstructures. Ca2+ ions, e.g., direct the assembly of tubulin into 50 nm sized, ring-like structures. In our approach, these ring-like protein assemblies serve as a functionalized scaffold where the metal particles are generated in situ and deposited into spiral-shaped particle arrays, reflecting the arrangement of the protein subunits within the assembly. The resulting size and crystalline structure of the materials were examined using transmission electron microscopy and scanning force microscopy.

Since chemists and materials scientists have been seeking for unconventional routes to synthesize and fabricate novel patterns for applied nanotechnology, we introduced useful functional polymers, which can be patternable on a variety of substrates to fabricate devices with specific functions. We introduce new silicon elastomeric polymers as a stamp material for high fidelity in nano-scale soft lithography. We also fabricated elastic photopatterns by synthesizing photocurable PDMS prepolymers. Photopatternable polymers with specific molecular recognition functions were also employed to fabricate functional patterns with specific functions for our diverse applications.