Simple cycloalkylsilanetriols RSi(OH)3 [R =c- pentyl (1</b>) and c-hexenyl (2b</b>)] were synthesized as white powders in 70% and 90% isolated yields, respectively, from the hydrolysis of the corresponding trialkoxysilanes with mild acidic water. Silanetriols 1</b>,2</b> are soluble in water and polar organic solvents such as alcohol, acetone, THF, DMSO, and etc. They can be applied as surface modifiers for inorganic materials such as silica and titania through simple two step processes: 1) organosilanetriol interact with hydroxyl groups on inorganic materials through hydrogen bonding to make molecular layered thin coating on the inorganic surface, 2) then can undergo condensation by heating about 110 ℃ above to form M-O-Si covalent bond to give hydrophobic silica. With the treatment of ca. 50 nm spherical silica with 5 wt % alkylsilaneol 1, no precipitation of silica particles in water was observed, indicating good surface modifiers for silica particle. In this presentation we will discuss the application of silanetriols as surface modifier for inorganic materials such as silica and titania particles.

We have been developing noble metal nanoparticles and nanocomposites for large scale application to glass surfaces. The novel functionality of the nanocomposites is attributed to the properties of both the metal nanoparticles and host matrix. Here a single-process route to nanocomposite thin films by spray deposition technique has been investigated. Preformed gold nanoparticles have been incorporated into several different transition metal oxides (TiO2, SnO2, ZnO). The nanocomposite films showed intense coloration due to the surface plasmon resonance effects of gold nanoparticles embedded in the host matrix. The gold nanoparticles were found well embedded into the host metal oxides homogeneously. This film deposition method can easily be scaled up and is compatible with current industrial on-line processes.

ZnO nanowire arrays are grown on carbon fiber to enhance the interface strength of a polymer matrix composite without degrading the base fiber and in-plane strength of the composite. The morphology of the nanowire array is controlled during growth to create nanowires with different aspect ratios to elucidate the structure-property relations of the interphase. Nanowires are shown to double the composite interfacial shear strength at an intermediate nanowire length, indicating that an optimal point exists and the interface can be engineered to maximize the interfacial enhancement. Furthermore, the observed effect of the morphology on interface strength indicates that the bond between the ZnO nanowire array and the carbon fiber is quite strong, more than twice as strong as the interaction between the matrix and control fiber.

Nanostructured materials have attracted considerable interest in recent years due to their properties which differ strongly from their bulk phase and potential applications in nanoscale electronic and optoelectronic devices. Metal oxide nanostructures can be synthesized by variety of different synthesis techniques developed in recent years such as thermal decomposition, sol-gel technique, chemical coprecipitation, hydrothermal process, solvothermal process, spray pyrolysis, polyol process etc. All the above processes go through a tedious synthesis procedure followed by prolonged heat treatment at elevated temperature and are time consuming. In the present work we describe a rapid microwave irradiation-assisted chemical synthesis technique for the growth of nanoparticles, nanorods, and nanotubes of a variety of metal oxides in the presence of an appropriate surfactant, without the use of any templates The method is simple, inexpensive, and helps one to prepare nanostructures in a very simple way, and in a very short time, measured in minutes. The synthesis procedure employs high quality metalorganic complexes (typically -diketonates) featuring a direct metal-to-oxygen bond in its molecular structure. The complex is dissolved in a suitable solvent, often with a surfactant added, and the solution then subjected to microwave irradiation in a domestic microwave oven operating at 2.45 GHz frequency with power varying from 160-800 W, from a few seconds to a few minutes, leading to the formation of corresponding metal oxides. This method has been used successfully to synthesize nanostructures of a variety of binary and ternary metal oxides such as ZnO, CdO, Fe2O3, CuO, Ga2O3, Gd2O3, ZnFe2O4, etc. There is an observed variation in the morphology of the nanostructures with the change of different parameters such as microwave power, irradiation time, appropriate solvent, surfactant type and concentration. Cationic, anionic, nonionic and polymeric surfactants have been used to generate a variety of nanostructures. Even so, to remove the surfactant, there is either no need of heat treatment or a very brief exposure to heat suffices, to yield highly pure and crystalline oxide materials as prepared. By adducting the metal complexes, the shape of the nanostructures can be controlled further. In this manner, very well formed, single-crystalline, hexagonal nanorods and nanotubes of ZnO have been formed. Adducting the zinc complex leads to the formation of tapered ZnO nanorods with a very fine tip, suitable for electron emission applications. Particle size and their monodispersity can be controlled by a suitable choice of a precursor complex, the surfactant, and its concentration. The resulting metal oxide nanostructures have been characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, FTIR spectroscopy, photoluminescence, and electron emission measurements.

ZnO nanostructures were grown by pulsed laser deposition on c-plane sapphire substrates. The as-grown nanostructures were examined by scanning electron microscopy and transmission electron microscopy ZnO nanowires were grown using a gold catalyst, at a high substrate temperature of 800°C and an ambient gas pressure of 0.5 mbar (5% oxygen, 95% argon). Changing the gas composition to pure oxygen led to the growth of stacking fault-free ZnO nanosheets with their growth direction inclined to the [0001] direction. Similar nanosheets with stacking faults were found when lowering the growth temperature to 600°C for a 5% oxygen – 95% argon ambient gas composition and the same overall pressure. A growth mechanism for these ZnO nanosheets is proposed.

A dry etch recipe was developed for porous nanostructured TiO2 thin films fabricated using glancing angle deposition (GLAD). Unlike wet chemical etches, the technique reported here preserves the vertical post nanostructure, eliminating clumping. A highly controllable and easily tailored reactive ion etching process with CF4 alone, or combined with O2, was investigated. The anisotropic etch modifies the morphology and density of standard GLAD films, which is of interest for sensing applications.

Zinc oxide (ZnO) is a metal-oxide semiconductor that has attracted resurgent interest as an electronic material for a range of device applications. In our work, we have focused on how defect properties change as one goes from the bulk to the nanoscale. Infrared (IR) reflectance spectra of as-grown and hydrogen-annealed ZnO nanoparticles were measured at near-normal incidence. The as-grown particles were electrically semi-insulating, and show reflectance spectra characteristic of insulating ionic crystals. Samples annealed in hydrogen showed a significant increase in electrical conductivity and free-carrier absorption. A difference was observed in the reststrahlen line shape of the conductive sample compared to that of the as-grown sample. In addition to hydrogen doping, we successfully doped ZnO nanoparticles with Cu. To probe the electronic transitions of Cu2+ impurities in ZnO nanoparticles, IR transmission spectra were taken at liquid-helium temperatures. Two absorption peaks were observed at energies of 5781 and 5821 cm-1. Finally, we tentatively assign a series of IR spectral lines to Na acceptors.

Highly monodisperse ZnO:Eu3+ nanocrystals have been synthesized by modified sol-gel method from ethanolic solutions. The effect of Eu3+ ions (x=0.05-0.30) concentration on the structural, optical and luminescent properties has been evaluated. No other than the ZnO-wurtzite phase was observed at all dopant levels, which was confirmed by FT-IR and Raman spectroscopy techniques. A blue shift of the exciton peak and the increase on the corresponding band gap were observed at increasing Europium contents, which would indicate an interaction between Eu3+ ions and the development of the ZnO host structure. The luminescence properties were also dependent on Europium contents; a systematic blue shift and enhancement of the intensity of visible luminescence peak, attributed to an increment of surface defects, was observed by a rising Europium concentration. The red luminescence band, representing the 5D0→7F0 transition, was clearly observed in nanocrystals after annealing at 300OC for one hour. The presence of this band could be considered as an evidence of the effective energy transfer from ZnO to Eu3+ ions.

Flowerlike ZnO nanoneedle arrays have been synthesized on Si (100) substrates by pulsed laser deposition techniques. The tips of the nanoneedles are ˜ 20- 50 nm in diameter and their roots are as thick as ˜ 50- 100 nm. The nanoneedle arrays grow preferentially along the [0001] direction. Raman spectroscopy shows three first order optical normal modes which confirm wurtzite structure of ZnO nanoneedles. In the low frequency zone, additive modes (92, 122, 163, and 275 cm-1) are observed and can be attributed to zone boundary phonons. ZnO nanoneedle arrays exhibit a strong UV luminescence emission, and two strong peaks at 3.258 eV and 3.288 eV are observed.

Zinc oxide (ZnO) nanowires (NWs) are receiving significant industrial and academic attention for a variety of novel electronic, optoelectronic and MEMS device applications due to their unusual combination of physical properties, including being optically transparent, semiconducting and piezoelectric. Hydrothermal growth is possible at significantly lower temperatures (and hence lower thermal budgets) compared with other NW growth methods, such as chemical vapour deposition. In this context, the hydrothermal growth of ZnO NWs on seeded substrates immersed in equimolar zinc nitrate/HMTA aqueous solution was investigated. NWs were grown on polished silicon (001) substrates, and the solution concentrations, temperatures and growth times were varied. Importantly, the NW diameter was found to depend only on concentration during hydrothermal growth for times up to 4 hours. The average diameter was 14 nm in 0.005 M solution and increased up to a maximum 150 nm at 0.07 M, when the NWs formed a continuous polycrystalline film. Concentration and temperature were all found to affect the axial growth rate of NWs in the [0001] direction. The growth rate was constant up to 4 hours (200 nm hr-1) for constant conditions (81 oC, 0.025 M). The growth rate was found to increase approximately linearly with concentration at a rate of 7840 nm M-1 hr-1 up to 0.06 M (81 oC solution). The growth rate also increased linearly with temperature at a rate of 4.9 nm hr-1 K-1 (0.025 M solution). This indicates that growth takes place close to the equilibrium point, found by linear regression to be 36 oC for 0.025 M solution.

We have synthesized W and Mo doped VO2 nanoclusters embedded in 200 nm thick thermally grown SiO2 on 4-inch silicon wafers by sequential ion implantation of the elements V, W, Mo and O. The implantation energies have been chosen to locate the mean projected range in the centre of the SiO2 thin film. A post implantation rapid thermal annealing step in flowing Ar at 1000°C for 10 min leads to the growth of doped VO2 nanoclusters. The optical properties of the nanoclusters were analyzed by temperature dependent spectral ellipsometry in the spectral range of 320 to 1700 nm. It will be shown, that the semiconductor-metal phase transition hysteresis width starting at 50K in the undoped case can be systematically closed by increasing dopand concentration.

The film of MgO-AlN system was manufactured by the conventional magnetron sputtering process. It is observed that a Fermi level could be raised by letting AlN composition increase, confirmed by ultraviolet (UV) photon energy dependence of the electronic emission, and investigated with XPS that the surface reaction, such as surface hydroxide / carbonate of MgO, could be controlled in addition of AlN. The glow discharge characteristics for MgAlON films were evaluated from the minimum pressure that a glow discharge is started under constant RF power, which correspond to the result of the analysis for the secondary electron emission coefficient, using Metastable De-excitation Spectroscopy (MDS).

We deposited various nano structured ZnO thin films with plasma treatment on an alumina substrate and fabricate ZnO sensors for acetone detection. The ZnO sensors with various nano structures and the plasma treatment were deposited by radio frequency (RF) magnetron sputtering method with RuO2 micro heater and Ru electrode. In order to control a work function intentionally, the various deposition conditions and the plasma treatment were used. Sensitivities of the ZnO sensor were measured in acetone vapor and air at 250 degree C. In conclusion, we suggested that the sensitivity of ZnO sensors for acetone strongly depends on the work function of the as-deposited or plasma treated nano structured ZnO thin films.

Current-voltage (I-V) characteristic of Pt/TiO2-x/Pt has been investigated. The Pt/TiO2-x/Pt devices in the initial state exhibit a rectifying I-V behavior. By applying a pulse voltage, the rectifying polarity could be switched to an opposite direction. The mechanism of the rectifying polarity switch is proposed as the local drift of defects, such as oxygen vacancies (VO), due to applying pulse voltage. It is found that the required pulse voltage height for the polarity switch (Vswitch) exhibits much dependence on the operation temperature and width of applied pulse voltage. With an increase of the pulse voltage width or the measurement temperature (T), Vswitch exhibits a decrease with increase of T. These results suggest that the rectifying polarity switch in the Pt/TiO2-x/Pt is attributed to a thermal and dynamic dependence process, which agree well with the localized migration of VO induced by applied pulse voltage.

The ZnO thin film was successfully deposited on a glass substrate at RT by a RF reactive magnetron sputtering method. Structural, chemical, optical, and hydrophilic/hydrophobic properties are measured by using a surface profilometer, an x-ray diffractometry (XRD), an x-ray photoelectron spectroscopy (XPS), a UV-VIS spectrophotometer, and a contact angle system, respectively. Results show that the deposition rate decreases with increasing O2/(Ar+O2) ratio. Otherwise, the best stoichiometric and quality of ZnO thin film was observed at 0.30 of O2/(Ar+O2) ratio by the smallest FWHM and the strong O-Zn bonds. Regardless of O2/(Ar+O2) ratio effect or thickness effect, high transmittance (> 86%) in the visible region is observed, while the UV-shielding characteristics depend upon both the magnitude of film thickness. The film thickness plays a more prominent role in controlling optical properties, especially in the UV-shielding characteristics, than the O2/(Ar+O2) ratio. However, the hydrophobic characteristics can be obtained when the glass coating with ZnO thin films. In general, with properly coated ZnO thin film, we can obtain a glass substrate which is highly transparent in the visible region, has good UV-shielding characteristics, and possesses highly hydrophobic characteristics (self-clean capability), which is highly suitable for applications in the glass industries.

Thin films of vanadium dioxide (VO2) exhibit an interesting semiconductor to metal transition (SMT) when heated above ˜680C in which its resistivity changes by 3-4 orders of magnitude and its transmittance for IR wavelengths drops drastically. Integration of these thin films with Si (100) substrate is of immense technological importance due to its potential applications in sensor and memory based devices. Using pulsed laser deposition (PLD) we have demonstrated in this study that thin films of VO2 can be grown epitaxially on Si (100) substrate using an intermediate tetragonal Yttrium-Stabilized Zirconia (YSZ) layer without any further annealing. X-ray diffraction (XRD) and cross-section transmission electron microscopy studies were performed on the films and they are found to be of highly epitaxial nature. Electrical resistivity measurement were carried out using the four-point probe method and SMT parameters were extracted using Gaussian fit of the data. The S-M transition parameters are in close proximity with parameters obtained from vanadium oxide films deposited on oxide based substrates such as Al2O3 or TiO2.

Conventional growth of zinc oxide (ZnO) nanowires (NWs) is typically carried out using vapor liquid solid (VLS) and chemical vapor deposition (CVD) methods. While these methods are effective, they often involve the use of specialty gasses and equipment. We have discovered that ZnO NWs grow spontaneously from zinc (Zn) films (thermally evaporated on silicon (Si) substrates) when the films are merely heated on a hot-plate in air at ambient pressures for 10 minutes. This process does not involve any metal catalysts, seed layers, specialty gasses or surface treatments in forming patterned regions (on silicon substrates) of NWs with typical diameters in the range of 20-50 nm and lengths of 2-3 μm.

In this report, we describe recent efforts in fabricating new nanocarbon-supported titanium dioxide structures that exhibit high surface area and improved electrical conductivity. Nanocarbons consisting of single-walled carbon nanotubes and carbon aerogel nanoparticles were used to support titanium dioxide particles and produce monoliths with densities as low as 80 mg/cm 3. The electrical conductivity of the nanocarbon-supported titanium dioxide was dictated by the conductivity of the nanocarbon support while the pore structure was dominated by the titanium dioxide aerogel particles. The conductivity of the monoliths presented here was 72 S/m and the surface area was 203 m2/g.

The morphological and microstructural evolution associated with an exsolution driven self-nanostructuration process of La0.7Sr0.3MnO3 films, is investigated using scanning force microscopy, reciprocal space mapping and transmission electron microscopy. The focus is placed on the misfit strain relaxation mechanism. Surfaces with atomically flat terraces are already developed after 1hour at 1000 °C while first fingerprints of phase exsolution do not appear until 9-10 hours. X-ray diffraction reciprocal-space mapping reveals that 24 nm thick films remain strained during the whole microstructural evolution, while 12 hour annealed films undergo almost total plastic relaxation of the misfit strain at a thickness of 60 nm. Overall, these results point to a kinetic limitation of dislocation mechanisms. It is argued that chemical relaxation provides a significant contribution to misfit strain relief.

Reduction of parasitic capacitances and improvement of the on-off current ratio (ION/IOFF) can be achieved by increasing the gate control in Field Effect Transistors (FETs). Multiple gated FETs (MugFETs) lend themselves well for this. The MugFET investigated in this manuscript is the Screen Grid FET (SGrFET) that consists of multiple gate cylinders inside the channel perpendicular to the current flow. In this work we illustrate, using 2D Technology Computer Aided Design (TCAD), that the multiple geometrical degrees of freedom of the SGrFET can be exploited to simultaneously optimise the on-current, ION and the gate-drain Miller parasitic capacitance for increased switching speed.