Pulsed electron beam ablation (15 keV, 1 kA, 100 ns) has been used to grow thin films of nanocrystalline diamond on silicon substrates. The films have been grown at room temperature and 150°C, and under argon as the working background gas at a pressure of about 4 mTorr. Visible reflectance spectroscopic analysis has shown films thickness to range between about 55 nm and 115 nm. Visible-Raman spectroscopic measurements have confirmed the presence of sp3 carbon bonds with a substantial fraction in the deposited films, and surrounded by a graphitic phase. The morphological features of the films have been assessed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The films surface is relatively smooth at room temperature and for low thickness, and becomes rougher at high temperature and for thicker films.

Synthetic chemists are paying ever more attention to enabling technologies as a means to opening the paths towards the double goal of achieving high efficiency and meeting green criteria. Non-conventional techniques that create unique environments which promote selective modification have been investigated by many as part of the search for more highly efficient synthetic derivatization of cyclodextrins (CD). A few optimized microwave-assisted protocols have so far been developed for the preparation of selective per-alkylated aminocyclodextrin. In this work, a series of β-CD derivatives, whose primary hydroxyls were all replaced by amino groups, has efficiently been synthesized from per-(6-iodo-6-deoxy)-β-CD via nucleophilic substitution with amines under microwave irradiation in closed vessel (N2 pressure). The reduction of per-(6-azido-6-deoxy)-β-CD to per-(6-amino-6-deoxy)-β-CD via catalytic hydrogenation has also been successfully carried out under dielectric heating.

MOS capacitor composed of nc-CdSe embedded ZrHfO high-k gate dielectric stack was fabricated and characterized for nonvolatile memory functions. Detailed material and electrical properties have been investigated. With a large charge trapping capability, this kind of device can trap electrons or holes depending on the polarity and magnitude of the applied gate voltage. For the same stress time, the device trapped more holes than electrons under the same magnitude of gate voltage but different polarity. The negative differential resistance peak was observed at the room temperature due to the Coulomb blockade effect. The charge trapping mechanism was delineated with the constant voltage stress test. After 10 years of storage, about 56% of trapped charges still remain in the device.

In order to understand the vacancy behavior during incubation period before steady state void swelling, positron annihilation lifetime measurements was performed after isochronal annealing of austenitic stainless steel (Ti added modified SUS316SS) and ferritic stainless steel (F82H) irradiated by neutrons and electrons to a dose of 0.2 dpa. By electron and neutron irradiations below 363 K, vacancies and nano-voids containing of few vacancies were formed in both alloys. By increasing annealing temperatures, the lifetime decreased without forming nano-voids. The change of lifetime during the annealing indicated the formation and growth of staking fault tetrahedra (Ti added modified SUS316SS) and the annihilation of vacancies at precipitates (F82H).

High-quality (010)-oriented epitaxial β-FeSi2 films were grown on Si(110) substrates by coating silver thin layer. The full width at half maximum of the rocking curve of β-FeSi2040 was 0.14o for the film deposited at 800°C on Si(110) substrates with 95 nm-thick silver layer. Moreover, this epitaxial β-FeSi2 film was constructed with single domain structure, and the lattice parameter of a-axis was extended by 0.7%. The photoluminescence spectrum from this epitaxial β-FeSi2 indicated that the band-gap was modulated by lattice strain of a-axis.

Using molecular dynamics simulations, we demonstrate a transportation mechanism of hydrogen molecules enabled by the torsional buckling instability of carbon nanoscrolls. The transportation mechanism is shown to be of high efficacy and robust over a range of loading rates. The findings shed light on potential application of carbon nanoscroll based hydrogen storage.

Indium Tin Oxide (ITO) has been widely used as a Transparent Conductive Oxide (TCO) layer in the photovoltaic solar technology because of its excellent electrical and optical properties. However, ITO is brittle, and its conductivity decreases significantly as the ITO films are exposed to stretching or bending strains especially in flexible/foldable solar cell applications. The cracks in ITO appear at very low strains which might cause failure in the conductive layer because of the combination of a very thin film of brittle ceramic material applied to a polymer substrate. Poly (3, 4-ethylenedioxythiophene), abbreviated PEDOT, is of increasing interest as a competitive candidate to ITO. PEDOT has found its way in many applications such as transparent electrode materials and transparent conductive layers in photovoltaic solar cells. In this work, the mechanical behavior of PEDOT was studied under high cycle bending fatigue in which the effects of bending diameter and bending frequency were considered and compared to ITO. High magnification optical images were used to study cracking in the PEDOT as well as the ITO layers. In flexible solar cells, the web will be exposed to folding/bending many times during manufacturing and installation. Therefore, the thin film substrate structure will be exposed to cyclic loading cyclic tensile and compressive strains. Therefore, this work was designed to mechanically fatigue the structure and study its behavior. It was found that bending diameters as well as material (PEDOT or ITO) have a great influence on the electrical conductivity of the thin films.

Supercapacitor devices promise to be an effective means of storing energy, and delivering power for personal electronics, remote sensors, and transportation.1, 2 Rare earth metals, such as ruthenium, have been used and report high value of capacitance, specific power, and energy.4 Nevertheless, the rarity of such metals prevent their practical use. In this study we utilize an earth-abundant nickel and a controlled microwave synthesis to create nickel oxide (NiO) with an optimal nanostructure for capacitance. To surpass the lofty series resistance associated with metal oxides such as NiO, we exploit the conductive properties of single and multi-walled carbon nanotubes. The carbon nanotubes and NiO can benefit from the presence of each other by preventing unnecessary aggregation.

Efficient charge transport is key to the operation of the various devices based on organic semiconductors, such as OLEDs, OPVs and OFETs. Both academia and industry are investing heavily in the development of new organic materials and processing techniques to improve device performance. An important parameter to tweak is the mobility of charge carriers. Triggered by an experimental result, here we investigate whether this parameter can be probed indirectly using UV-VIS spectroscopy. This would simplify the process of characterization and optimization of the mobility in amorphous molecular films, for example.

Molten salt flameless oxidation of graphite is one of the prospective methods of irradiated graphite waste processing. Molten salts are capable to retain a considerable part of radionuclides, to neutralize acidic off gases, moreover spent salts could be vitrified on completion of the process. We have used thermodynamic modelling to assess the efficiency of molten salt oxidation of graphite. Equilibrium compositions of both the melt and the off gas were calculated depending on graphite content and temperature. The feasibility of decontaminating the irradiated graphite of its near-surface layers using complete molten salt oxidation was investigated in a series of laboratory experiments. As the molten salt medium used to oxidize irradiated graphite we have investigated lithium, potassium and sodium carbonates. Sodium sulphate, boron oxide, barium and potassium chromates were also used as oxidizers. Tests were carried out at 870–1270 К. The efficiency of decontamination of graphite blocks has been assessed based on the activity of 137Cs and 60Со in the samples before and after molten salt oxidation. Data obtained demonstrated the feasibility of decontamination by molten salt removal of near surface layers on irradiated graphite blocks. Decontamination rate and efficiency depend on oxidizers used and temperature of process.

A tabletop prototype of a roll-to-roll (R2R) direct stamping apparatus has been developed. The prototype is about 100 cm long, 30 cm wide and 40 cm high and is operational up to the web speed of 1 m/min. While upper rolls carry a web with a patterned stamp on it clockwise, a sprayer on top of the R2R apparatus dispenses the nano-ink to fill in the stamp. Two other rolls with adhesive films completely remove the residual layer on the stamp. Final products remain on the substrate after de-stamping in which the web rolls up and the substrate moves to the further right. This roll-to-roll direct stamping apparatus demonstrates high throughput and material efficiency for fabrication of flexible micro- and nano-electronic devices.

Density functional theory calculations are used to address the energetics of protons crossing “triple phase boundaries” based on Pd and barium zirconate. Our calculations show that the proton transfer reaction at these triple phase boundaries is controlled by the terminal layer of the electrolyte in contact with the metallic catalyst and gas phase. Hydrogen spilling onto the electrolyte surface is energetically favored at peripherical sites of the metal-electrolyte interface, and proton incorporation into the sub-surface region of the electrolyte involves energies of the order of 1 eV. At the triple phase boundary, the energy cost associated with the proton transfer reaction is controlled by both the nature of chemical contact and the Schottky barrier at the metal-electrolyte interface.

Titanium (Ti) is the material of choice for orthopaedic applications because it is biocompatible and encourages osteoblast ingrowth. It was shown that the biocompatibility of Ti metal is due to the presence of a thin native sub-stoichiometric titanium oxide layer which enhances the adsorption of mediating proteins on the surface [1]. The present studies were devised to evaluate the adhesion, survival, and growth of cells on the surface of new engineered nano-crystal films of titanium and titanium oxides and compare them with orthopaedic-grade titanium with microcrystals. The engineered nano-crystal films with hydrophilic properties are produced by employing an ion beam assisted deposition (IBAD) technique. IBAD combines physical vapor deposition with concurrent ion beam bombardment in a high vacuum environment to produce films (with 3 to 70 nm grain size) with superior properties. These films are “stitched” to the artificial orthopaedic implant materials with characteristics that affect the wettability and mechanical properties of the coatings.

To characterize the biocompatibility of these nano-engineered surfaces, we have studied osteoblast function including cell adhesion, growth, and differentiation on different nanostructured samples. Cell responses to surfaces were examined using SAOS-2 osteoblast-like cells. We also studied a correlation between the surface nanostructures and the cell growth by characterizing the SAOS-2 cells with immunofluorescence and measuring the amount alizarin red concentration produced after 7 and 14 days. The number of adherent cells was determined by means of nuclei quantification on the nanocrystalline Ti, TiO2, and microcrystalline Ti and analysis was performed with Image J. Our experimental results indicated that nanocrystalline TiO2 is superior to both nano and microcrystalline Ti in supporting growth, adhesion, and proliferation. Improving the quality of surface oxide, i.e. fabricating stoichiometric oxides as well as nanoengineering the surface topology, is crucial for increasing the biocompatibility of Ti implant materials.

We report a preliminary study on the influence of indium doping on ultra-thin film silicon solar cells. The design of the cell reported here is such that it should elucidate the impact of the indium dopant, which is concentrated in the thin film. Indium, a deep level in silicon (0.157 eV above the valence band), acts as a p-type dopant and a sensitizer. Absorption through sub-bandgap transitions is expected based on the previously reported Impurity PhotoVoltaic (IPV) Effect [1]. It is proposed that the implementation of a novel vertical PN junction configuration together with the IPV effect enhances the efficiency of ultra-thin solar cells. The most efficient cell fabricated to date, in our research group, has a conversion efficiency of 4.3 % (active silicon thickness of 2.5 μm), a short-circuit current density of 14.9 mA/cm2 and an open-circuit voltage of 0.51 V under 1 sun illumination. The cell has not been optimized with any type of light trapping technique and 11.24 % of the cell surface is covered by the metal contacts. Numerical simulation indicates that for the geometry used, the maximum efficiency that may be expected is 9.8 % (compared to the 4.3 % measured).

The use of light weight structural materials such as titanium in transport systems like aero planes leads to a significant reduction in fuel consumption. However, titanium and its alloys cannot be used at elevated temperatures above 500°C for several reasons. Today aero engine compressors are made of a mixture of light Ti- and heavy Ni-alloys. The improvement of Ti-alloys to withstand the conditions in the high pressure compressor i.e. temperatures above 500°C would enable the manufacturing of a compressor from titanium as a whole with all its associated benefits. Intermetallic TiAl-alloys are another class of light weight materials for several high temperature applications. The use of TiAl as low pressure turbine (LPT) blades in the last sections of a large jet engine could save up to 150 kg of weight. In the last sections of the LPT the temperature is quite moderate (max. 650°C). The improvement of the high temperature capability of TiAl would allow its use in hotter sections of the engine with additional weight reduction. Similarly, the response performance of TiAl-turbocharger rotors in automotive engines would be much faster compared to the heavy Ni-based alloys used today. Furthermore higher rotation speeds are possible. Due to the novel so called fluorine effect the oxidation mechanism of TiAl can be altered. Fluorine-treated TiAl-components are protected by an alumina layer formed during high temperature exposure in oxidizing environments. This effect can be transferred to Ti-base materials if they are enriched with aluminum in a thin surface zone. The concepts and the results of high temperature exposure experiments of treated Ti- and TiAl-specimens are presented in this paper. They are discussed in the view of a use for real components.

One dimensional photonic crystal 1D-PhC silicon waveguide resonators with quality factor, Q∼105, are demonstrated at mid-infrared wavelengths between 2 um to 5 um. Silicon has several advantages for mid-infrared applications including its broad mid-infrared transmission spectrum which extends out to 9 um, CMOS compatible fabrication processing, and ease of electronic-photonic integration. The proposed resonators are composed of photonic crystal cavities with optimized (i) lattice parameter a, (ii) cavity width w and (iii) hole radius r. Finite difference time domain (FDTD) simulations are used to adjust these three parameters, a, w, and r, to select a resonant frequency of interest within the mid-infrared spectral range. Due to the high quality factor Q, these PhC silicon waveguide resonators have much higher sensitivity as chemical sensors and have the potential to replace bulky instruments such as an FTIR.

This work investigates scanning laser annealing used for ultra-shallow junction (USJ) activation. We investigate the laser system via simulation to determine the peak temperature achieved in the active area during processing. We employed the Sentaurus TCAD software by Synopsys to perform a 2D simulation of a laser scans across the active area of the device, solving the heat equation in both time and space. An absorber layer is deposited on the wafer surface to enhance the absorption of incident energy and reduce SOI reflectivity. An effective absorption coefficient of α=8000cm-1 was calculated for the absorber layer, calibrated with the experimental laser intensity. This absorption coefficient correctly predicts the silicon temperature as a function of power with any arbitrarily defined scan speed. To investigate the role of dopant activation, an SOI wafer was implanted with arsenic 25 keV, dose 3e15 /1.5e15 cm-2 and laser annealed in areas of target temperatures ranging from 850-1300°C. The sheet resistance was measured using 4-point probe showing sheet resistance improvement with increasing laser temperature. The extracted temperature cycle from the 2D heat simulation was used as an equivalent millisecond RTA in a full 3D process simulation to study dopant distribution and activation using Sentaurus Process Kinetic Monte Carlo (KMC), considering the effect of dopants, dopant clusters, and point defects. The results of this simulation demonstrate deactivation of arsenic above 1050°C, which is inconsistent with Hall measurements that suggest increasing laser temperature will increase mobility and activation. The results are analyzed versus the expected trends and suggest future improvements needed to the KMC model or the laser temperature profiles in order to describe activation kinetics in millisecond anneals within SOI.

The metallic binary-alloy fuel Uranium-Zirconium is important for the use of the new generation of advanced fast reactors. Uranium-Zirconium goes through a phase transition at higher temperatures to a (gamma) Body Centered Cubic (BCC) phase. The BCC high temperature phase is particularly important, since the BCC phase corresponds to the temperature range in which the fast reactors will operate. A semi-empirical MEAM (Modified Embedded Atom Method) potential is presented for Uranium-Zirconium. The physical properties of the Uranium-Zirconium binary alloy were reproduced using Molecular Dynamics (MD) simulations and Monte Carlo (MC) simulations with the MEAM potential. This is a large step in making a computationally acceptable fuel performance code.

Aiming the understanding of how the application to devices is affected by the presence of oxygen in semiconductor nanostructures, Al/Ge-nanowires Schottky devices were fabricated without any previous treatment to remove the native oxide from nanowires' surface, originated during the growth process. Electronic transport properties of these devices were investigated and it was observed that interface states originated from the disordered oxide layer effectively pinned the Fermi level at the Ge surface, affecting Schottky barriers. Numerical calculations were made to complement this study agreeing with experiments.

We explore a model of heat transport between two heat reservoirs mediated by a quantum particle. The reservoirs are modeled as ensembles of harmonic modes linearly coupled to the mediator. The steady state heat current, as well as the thermal conductance are obtained for arbitrary coupling strength and will be analyzed for the cases of weak and strong coupling regimes. It is shown that the violation of the virial theorem – the imbalance between the average potential and kinetic energy of the mediator – can be considered as a measure of the coupling strength that takes into account all the relevant factors. The dependence of the thermal conductance on the coupling strength is non-monotonic and displays a maximum. Temperature dependence of the heat conductance may reach a plateau at intermediate temperatures, similar to the classical plateau at high temperatures. We will discuss the origin of Fourier’s law in a chain of macroscopically large, but finite subsystems coupled by the quantum mediators. We will also address the origin of the anomalously large heat current between the scanning tunneling microscope tip and the substrate in deep vacuum which was found in recent experiments.