Carbon capsules with hollow macroporous core/mesoporous shell were synthesized using sacrificial submicrometer-size solid core/mesoporous shell (SCMS) silica spheres as templates. Size of the hollow macroporous core and thickness of the mesoporous shell can be easily controlled by the choice of silica spheres and the amount of TEOS/C18-TMS mixture, respectively.

Inherently strained bilayers of In(Ga)As/GaAs, Epitaxially grown on top of an AlAs sacrificial buffer layer roll-up into free-standing nanotubes if they are released from their substrate by selective underetching, Here, we preseant a systematic study of the tube diameter as a function of total bilayer thickness and the ratio between the two layer thinknesses. We show that the diameters of the tubes are well described by a continous mechanical model.

The functional oxide thin films of electrochromic WO3-x and colossal magnetoresistive La0.8Sr0.2MnO3 were prepared by a KrF excimer pulsed laser deposition technique. Optical transparency and electrical conductivity of the WO3-x film were changed by the oxygen content in the lattice. Triclinic, tetragonal and amorphous WO3-x films were prepared by adjusting the oxygen atmosphere during the deposition. We revealed the relationship between the crystal structure and the gas sensing property of the films. The triclinic WO3-x film (1 μm) showed the high sensitivity to NO (60 ppm) gas at an operating temperature of 150°C. The colossal magnetoresistive La0.8Sr0.2MnO3 thin film having the MR ratio of 15 % (H=7 kG) was deposited under the conditions of the laser energy density of 2 J/cm2 (5Hz), substrate temperature of 850°C and oxygen pressure of 500 mTorr. The magnetic sensor composing of the La0.8Sr0.2MnO3 thin film responded to the AC magnetic field (1 kHz).

Two new inorganic-organic hybrid II-VI semiconductor nanostructures have been synthesized by solvothermal reactions. These nanostructures consist of inorganic 2∞[ZnSe] layers and organic bridging diamine molecules as spacers. The crystal structures of [ZnSe(dbn)1/2](1, dbn = 1,4-diaminobutane) and [ZnSe(hda)1/2](2, hda = 1,6-hexanediamine) have been determined by the powder X-ray diffraction method. They are isostructural and crystallize in the orthorhombic crystal system, space group Pbca(No.62), Z = 4. Crystal data for 1: a = 6.646(3), b = 6.473(3), c = 22.31(1) Å, V = 961.2(13) Å3, for 2: a = 6.6252(18), b = 6.4505(17), c = 27.138(7) Å, V = 1159.8(9) Å3. The optical absorption experiments show that both 1 and 2 generate a very large blue shift in the absorption edge (1.5-1.6 eV) due to a strong quantum confinement effect (QCE). Thermogravimetric behavior of both compounds has also been investigated.

The deterministic growth of ZnO nanorods using molecular beam epitaxy is reported. The process is catalyst-driven, as single crystal ZnO nanorod growth is realized via nucleation on Ag islands that are distributed on a SiO2-terminated Si substrate surface. Growth occurs at substrate temperatures on the order of 300-500°C. The nanorods exhibit diameters of 15-40 nm and lengths in excess of 1 μm. Nanorod placement can be predefined via location of metal catalyst islands or particles. This, coupled with the relatively low growth temperatures needed, suggests that ZnO nanorods could be integrated on device platforms for numerous applications, including chemical sensors and nanoelectronics.

Experimental investigations are presented regarding the surface-selective molecular selfassembly of fluorinated monochloroalkylsilane of the type (heptadecafluoro-1,1,2,2-tetrahydrodecyl) dimethylchlorosilane (denoted F17) on silicon dioxide (SiO2) and silicon nitride (Si3N4) surfaces. The goal is to investigate the controlled and selective surface self-assembly of these molecules as a potential route for substrate-selective covalent bonding of complex molecular assemblies to semiconductor substrates for on-chip interconnect and device applications. X-ray photoelectron spectroscopy (XPS), x-ray reflectivity (XRR) and atomic force microscopy (AFM) have been used to investigate the selectivity of the F17 self-assembly. Contrary to previous reported results, a high degree of F17 monolayer attachment selectivity is consistently observed between SiO2 and Si3N4 substrates for all three of the aforementioned monolayer characterization methods.

An automatic film formation system using an enhanced mass-controlled layer-by-layer sequential adsorption process was newly developed for the fabrication of ultra-thin organic films formed by various polymers, monomers, and inorganic materials. This technique can be applied to both water solutions and volatile solvents. In this process, a quartz crystal microbalance (QCM) was attached to the arm of a robot and the frequency shifts during the adsorption of the materials were monitored. By feeding back the data acquired by the QCM from the deposition to the dipping time, a high quality self-assembly film was produced. As a result, the interface roughness between the layers can be controlled within one nanometer. The cross-sectional TEM (transmission electron microscopy) observation of the films formed by the conventional time controlled dipping method and the newly established mass-controlled dipping method reveals that the interface of the heterostructure of the latter was much smoother than the former. In addition, this automatic dipping system can be applied not only for polyelectrolytes, but also for inorganic materials.

The formation of 10 nm self-assembled ZnO nanoparticles on Si and SiO2/Si surfaces, using diblock copolymers, and wet chemical processing compatible with semiconductor manufacturing, is reported. The diblock copolymer, consisting of norbornene and a norbornenedicarboxcylic acid blocks with a 400 to 50 repeat unit ratio, was synthesized by ring opening metathesis polymerization. The microphase separation of the block copolymer was employed to grow spherical self-assembled ZnO nanoparticles The self-assembly of the inorganic nanoparticles was achieved at room temperature in the liquid phase by incorporating ZnCl2 to the carboxylic acid block, or by exposure of a solid film to diethyl zinc vapors. Subsequent room temperature wet chemical processing of the doped films resulted in the formation of zinc oxide, followed by the saturation of double bonds in the polymer backbone. The formation of ZnO was verified by x-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM ) micrographs show the size and distribution of the zinc oxide nanoclusters in the polymer matrix. This study provided information on the formation of zinc oxide structures in a self-assembled polymer matrix, with the intention of controlling the shape and distribution of zinc oxide domains. The doped diblock copolymer was applied on Si and SiO2/Si wafers, by standard spinon techniques, and its photolithographic patterning metalization was developed.

We report about the fabrication of polymeric nanotemplates for the fabrication of regular arrays of nanocylindrical domains. Using combi-like macromolecules obtained by complexation of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) copolymer with a low molecular weight surfactant pentadecylphenol (PDP) we prepared thin polymer films deposited on a neutral substrate. The block-copolymer – PDP complex segregates into cylindrical morphology formed by P4VP-PDP fragments. The PDP molecules were easily removed by selective solvent (methanol) after annealing of the film. The resulting morphology consists of cylindrical channels of 7-8 nm in diameter oriented perpendicular to the substrate and regular packed in the hexagonal lattice with the period of 21 nm. Dry plasma etching, Atomic Force Microscopy (AFM), and Grazing Incidence Small Angle X-ray Scattering (GISAXS) were employed to characterize the films.

This present work deals with the temperature dependence on the growth and structure of CNTs grown by thermal CVD. The vertically aligned CNTs are synthesized on iron (Fe)-deposited silicon oxide (SiO2) substrate by thermal CVD using acetylene gas at temperatures in the range 750-950°C. Configuration and structural characteristics of CNTs have been investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). As the growth temperature increases from 750 to 950°C, the growth rate and the average diameter increase while the density decreases by a factor of about 2. TEM images show that the relative amount of crystalline graphitic sheets increases with increasing the growth temperature and a higher degree of crystalline perfection can be achieved at 950°C. The HRTEM images reveal consistently that the degree of crystalline perfection increases progressively as the growth temperature increases. This result demonstrates that the growth rate, diameter, density, and crystallinity of carbon nanotubes can be controlled with the growth temperature.

This paper demonstrates a new technique to form a patterned metal-oxide film on a silicon wafer using a local electric field. The idea of the technique involves using an interaction between metal-organic molecules dissolved in a non-polar solvent and a local electric potential field on a substrate. In this paper, an alkoxide and a metal-organic complex were used as metalorganic precursors. The precursor molecules were selectively deposited at the electrified region of the substrate. The deposited precursor films were heated with an electric furnace to form oxide films. Patterned TiOx and Sr-Ti oxide films were formed on a SiOx/Si substrate. These patterned thin films are potentially applicable to electric and optical devices. We believe that this new technique provides a new bottom-up process of molecular assembly for nanofabrication.

An efficient route to boron carbide, boron nitride, and silicon carbide ceramic nanofibers and nanotubules has been developed which employs newly developed molecular and polymeric precursors in conjunction with porous alumina templating methods. Melt infiltration or vacuum filtration of solutions of 6,6 -(CH2)6-(B10H13)2 or polyhexenyldecaborane through alumina templates followed by pyrolysis and dissolution of the membranes in 48% HF yielded boron carbide nanofibers or nanotubules. Boron nitride nanotubules were generated in a similar fashion by employing polyborazylene as a precursor, while silicon carbide nanotubules were generated from the commercially available allylhydridopolycarbosilane (AHPCS) polymeric precursor. In all cases, SEM and TEM analyses showed aligned, monodispersed ensembles of nanofibers or nanotubules. Structural control of the end products can be achieved through changes in concentration of the precursor solution, the number of alumina membrane treatments, and/or pore size of the alumina template.

RF-magnetron sputtered thin films of silver oxide (AgOx) were recently applied to ultra-high density optical data storage. It has been elucidated that the AgOx film sandwiched by protection layers shows very attractive characteristics in strong light-scattering, local plasmon generation and super-resolution by focussing a laser beam on it. Especially, the combination with an active recording film (optical phase change or magneto-optical) used in the currently recordable optical disks improves the storage density and overcomes the diffraction limit. In this paper, we describe the basic characteristics of nano-scale light scattering centers generated in the AgOx films and the interaction with ultra-high density recorded mark patterns in a near-field region. In addition, we provide the structural transition of the AgOx film by thermal and laser annealing treatment.

Since the discovery of surface-enhanced Raman spectroscopy (SERS) in 1977, scientists have come to understand the enhancement mechanism, but have been unable to consistently optimize the weak signals inherent in Raman experiments. Surface-enhanced Raman signals originate from excitation of the localized surface plasmon resonance (LSPR) of a nanostructured metal surface, thus producing concentrated electromagnetic fields at the surface of the nanostructure. Design of the nanostructured metal substrate plays an important role in understanding and optimizing SERS experiments. In this research, the size-dependent optical properties accessible by nanosphere lithography (NSL) are exploited to fabricate topographically predictable SERS-active substrates with systematically varying LSPRs. Correlated microextinction and micro-Raman measurements, as well as quantitative implementation of a Raman standard, allow significant improvements over the current method used to optimize SERS experiments. The knowledge gained in the novel plasmon scanned SERS excitation profiles clearly indicates the substrate parameters necessary for experimental optimization and promotes further understanding of the SERS enhancement mechanism.

Silicon nanowires catalyzed by Ti islands have been grown by molecular beam epitaxy (MBE) using Si2H6 as the gas source and characterized by in situ reflection high-energy electron diffraction (RHEED), scanning-electron microscopy (SEM) and transmission-electron microscopy (TEM). Approximately one monolayer of Ti was deposited on Si(001) wafers, which, during annealing, reacted with silicon and formed TiSi2 islands. After annealing, but before Si growth, the stoichiometric TiSi2 (C49) phase was observed with RHEED.

The silicon nanowires are typically between 20 and 40 nanometers in diameter and several hundred nanometers long. The nanowires changed their growth direction several times during growth, resulting in complex RHEED patterns, which can be matched very well by simulated RHEED patterns calculated assuming that the nanowires change their direction by twinning along (111) planes. RHEED patterns of epitaxial silicon nanowires, first-order twinned nanowires (twinned relative to the substrate orientation), second-order twinned nanowires (twinned relative to the first-order twin), and TiSi2 were observed.