Influence of different fluoride containing electrolytes on the formation of self-organized titania nanotubes by Ti anodization

The formation of self-organized porous titania nanotubes is achieved by electrochemical anodization under specific experimental conditions. In present work, the formation of porous titania nanotubes on titanium substrates is investigated in several SO₄²⁻/F⁻ based electrolytes. The presence of some non-porous layers covering the porous layers and accompanying the pore growth is observed. We discuss in details the influence of different electrolyte composition on the structure of self-organized porous layers, investigate the conditions for ideal pore growth. SEM investigations and XRD, AES and EDX surface analyses are carried out to characterize the self-organized porous layers. The results show that using SO₄²⁻/F⁻ electrolytes with different cations can drastically influence the final morphology of the self-organized porous nanotubes. We furthermore show that the nanotubes consist of TiO₂ and that they remain unchanged when annealed.     

Impact of Shear Strain and Quantum Confinement on $ langlehbox{110}rangle$ Channel nMOSFET With High-Stress CESL

In this paper, we propose a new analytical electron mobility model in strained Si inversion layers suitable for implementation in a drift-diffusion simulator. Using our new model, a numerical study in conjunction with comprehensive bending experiments has demonstrated that (100)-Si has the optimum channel direction along <110> in terms of the device performance of strained 65-nm-node nMOSFETs with contact etch stop layer and that both the shear-strain component and the quantum confinement effect are key factors in contributing to this superiority.     

Different Directions of Switching of Chromium Oxide Thin Films

We have investigated the switching behavior of as-deposited CrO _x and post-annealed CrO _y films by use of a variety of electrodes (top electrode Ag, Ti; bottom electrode Pt, fluorine tin oxide (FTO)). Resistance switching is highly dependent on electrode material and post-annealing treatment. Among Pt devices, I–V hysteresis was observed for the Ag/CrO _x /Pt device only; no resistance switching was observed for Ag/CrO _y /Pt, Ti/CrO _x /Pt, and Ti/CrO _y /Pt devices. Among FTO devices, I–V hysteresis was observed for the Ag/CrO _x /FTO device whereas I–V hysteresis with the opposite switching direction was observed for Ag/CrO _y /FTO, Ti/CrO _x /FTO, and Ti/CrO _y /FTO devices. The direction of switching depends not only on electrode material but also on post-annealing treatment, which affects the density of grain boundaries. Thus, the density of grain boundaries determines the type of charge carrier involved in the switching process. For as-deposited CrO _x films with a high density of grain boundaries Ag filament paths mediated by electrochemical redox reaction were observed, irrespective of bottom electrode material (Pt or FTO). Post-annealed CrO _y films with a low density of grain boundaries suppressed electrochemical redox reaction in the Ag/CrO _y /Pt device but promoted short-range movement of O^2? ions through the bottom interface, resulting in resistance switching in the Ag/CrO _y /FTO device. Electrochemical redox reaction-controlled resistance switching occurred solely in oxides with a high density of grain boundaries or dislocations.     

Property of Amorphous/Nanocrystalline Hybrid Wires of TiNi-Base Shape Memory Alloys

The microstructures and mechanical properties of amorphous/nanocrystalline hybrid TiNi wires produced by severe cold drawing were investigated. Annealed wires of Ti-50.9?mol%Ni and Ti-41?mol%Ni-8.5?mol%Cu were subjected to severe cold drawing of 50-70% reduction. The as-drawn TiNi wires were composed of the mixture of amorphous phase and predominantly B2 nanocrystalline phase. Young??s modulus increased with the drawing reduction which can be attributed to the increase in the amount of amorphous phase. For the binary TiNi wires, the volume fraction of amorphous phase was estimated to be about 60% from Young??s modulus and electrical resistivity. The wires drawn over 60% exhibited peculiar large linear elastic strain which is quite different from superelasticity. Aging at 573?K led to an increase in tensile elongation as well as in the recoverable strain. The amorphization by cold drawing was also confirmed for Ti-41?mol%Ni-8.5?mol%Cu in 62% drawn wires.     

Local electrical modification of a conductivity-switching polyimide film formed by molecular layer deposition

The electrical modification of a conductivity-switching polyimide film via molecular layer deposition (MLD) is studied for ultrahigh density data storage based on a scanning probe microscope (SPM). A PMDA-ODA (PMDA = 1, 2, 3, 5-benzenetetracarboxylic anhydride, ODA = 4, 4-oxydianiline) film as a recording medium is uniformly formed from a self-assembled monolayer on a Au surface by MLD. It is demonstrated that the conductivity of the film can be changed by applying a voltage between a SPM probe and the film. This conductivity-switching phenomenon is discussed by the molecular orbital approach and considered to be caused by the charge transfer effect or carrier trapping effect of PMDA-ODA.     

Application of synthetic fluid inclusions to simultaneous temperature–pressure logging in high-temperature (sub- to supercritical) geothermal systems

Batch-autoclave experiments have been conducted to evaluate the potential use of synthetic fluid inclusions as a simultaneous temperature–pressure (and fluid sampling) logging tool in deep-seated, high-temperature (>350 °C) geothermal systems. The application of synthetic fluid inclusions allows us to obtain information about thermal-pressure conditions in deep-seated geothermal systems, where conventional tools cannot be used because of the extreme temperature conditions. Fluid inclusions, up to 50 μm long, have been readily synthesized during 5-day autoclave experiments (conducted at 375–475 °C and 39–62 MPa) in pre-fractured, inclusion- and impurity-free artificial quartz. Inferred fluid inclusion (temperature–pressure) trapping conditions are calculated by deducing the intersection of isochores derived from microthermometric data for three sets of simultaneously trapped synthetic fluid inclusions in healed microfractures. Synthetic fluid inclusion logging offers a precise borehole temperature measurement technique without need of any pressure correction. Pressure estimates are less precise, although the method may be improved by using a combination of H₂O–NaCl and H₂O–KCl solutions/salinities, and fluid/quartz/amorphous silica systems that facilitate crack healing but trap fluids that do not homogenize at near-critical conditions.     

Advanced fabrication technologies of integrated-type structure for a-Si solar cells

This paper proposes a new advanced fabrication technology for a low-cost integrated-type a-Si solar cell. Integrated-type cells provide many advantages and have been industrialized with a laser patterning method. However, a higher throughput and more efficient patterning method was required for applying a-Si solar cells to a power generating system. Plasma CVM (Chemical Vaporization Machining) was first applied to advanced patterning because of its advantages of high speed and selectivity. In this method, a plasma generated under high pressure localizes near the wire electrode and concentrates reactive radicals. As a result, we achieved an etching rate of more than 1 μm/s and selective patterning of a 200 μm-wide a-Si layer in 1 s multiline patterning was also developed for large-area modules.     

Heat transfer of tubes closely spaced in an in-line bankTransfert thermique de tubes serres dans un reseau en ligneWärmeübergang in einem fluchtenden rohrbündelTeплoпepeнoc oт тpyб в кopидopнoм лyKhcyкe

An experimental investigation of heat transfer around four cylinders closely spaced in a cross-flow of air has been conducted. The cylinders are settled in tandem with equal distances between centers. Their inline pitch ratio is in the range of $\text{1.15 ≤}\text{c}\text{d ≤ 3.4}$ (c = distance between cylinders' centers, d = cylinder diameter); the Reynolds number ranges from 10⁴ to 5 × 10⁴. It is found that there exists a critical Reynolds number Red_c at which the heat transfer behavior changes drastically, and is correlated with the in-line pitch ratio by $\text{Red}{}_{\mathrm{c}}\text{= 1.14 × 10}{}^5\text{(}\text{c}\text{d)}{}^{\mathrm{?5.84}}$.Variations of characteristic features of the mean and local Nusselt numbers are discussed in relation to the length of the vortex formation region behind the cylinder.     

Resonant tunneling in quantum heterostructures: electron transport,dynamics, and device applications

The current understanding of the resonant tunneling process of electrons in double-barrier (DB) diodes and in coupled quantum well structures is described. The authors examine the validity of the simple Fabry-Perot model in describing the electron transport in actual DB diodes. They then describe a picosecond laser study to clarify the dynamics of resonant tunneling, including the intrinsic time delay associated with the multiple reflection of electron waves. Lastly, they discuss both the current state and prospects of device applications for high-speed electronics and optoelectronics