Fine Contact Research Articles

Photoelectrochemical properties of electrochemically deposited metal chalcogenide/ZnO films

In this work we studied metal chalcogenide sensitization of ZnO by electrochemical deposition which provides a fine electric contact between metal sulfide and the oxide. Deposition conditions to prepare the CdS/ZnO and Ag2S/ZnO films with optimized photoelectrochemical (PEC) properties are investigated. Effect of deposition technique, time, Mn-doping and post-annealing on photoresponse of the fabricated films are discussed. A short circuit current density of 1.42mA/cm2 and an open circuit potential of −1.39V (overall power conversion efficiency of 0.81%) have been achieved for the annealed Mn-doped CdS/ZnO electrode which is prepared by potensiostatic deposition. Potensiostatic deposition yields Ag2S in Acanthite form which is accompanied by ZnO degradation and the photoelectrode exhibits considerably enhanced and widened light absorption but lower overall power-conversion efficiency.

CONTACT STRENGTH OF MECHANOACTIVATED FINE CONCRETES FROM GRANULATED BLAST-FURNACE SLAGS

Purpose. Strengthening of fine concrete contact zone by mechanical processing of all components of the concrete mix in a mixer-activator and aggregate application with rough surface. Methodology. Rotary activator PC-06, developed by Scientific and Research Institute of Construction Technology, was used as a mixer-activator to achieve this purpose. Granulated blast furnace slag, having a more developed rough surface than sand, was used as fine aggregate. This apparatus provides intensive homogeneous mixing of concrete mix components, processing of raw materials (purification of their particles from contaminants), and mechanical destruction of granulated blast furnace slag surface layers and other components of the mix. Findings. During the preparation work, experimental research of new formations composition of fine concretes, using differential thermal and x-ray phase analysis methods, and physical-mechanical properties of fine concretes in accordance with the applicable standards of Ukraine, were carried out. It is established that the phase composition of new formations of fine concretes made from activated and non-activated mixes, is not changed. Their main difference is the size of generated effects and temperature intervals of occurrence of these peaks. Thus, in fine concretes made on the basis of the activated mixes, magnitude of effects is less, indicating a higher hydration degree of its components. Besides, TG curves of concrete specimens show that weight loss of gel calcium hydrosilicate of concrete from a mechanically activated mix is 0.5...0.7 % more than of concrete from a non-activated mix, which indicates a larger number of these formations in concrete from activated mixes. In general, concretes of different composition, made from a mix, processed in the mixer-activator, have higher mechanical strength. Originality. Ideas about the influence of mechanical activation of components of fine concrete mixes with forming humidity in a rotary mixer-activator on the value of the contact strength of cement and aggregates got further development. Practical value. Strengthening of contact area of fine concrete in the exercise of the combined machining of all concrete mix components in the mixer-activator is achieved owing to increment of hydration degree of raw concrete components; creation of conditions for solid-phase chemical reactions between its components; structure improvement of the received material. It promotes significant increase of mechanical strength of mechanoactivated fine concretes (around 5 times) in comparison with concretes, made from a non-activated mix, which makes it possible to decrease the cement consumption when manufacturing 1 m3 of concrete up to 59 %.

The Focused Ion Beam-SEM as a Critical Tool For Nano-scale Characterization of Highly Radioactive Nuclear Fuels

There are unique challenges associated with conducting nanometer and atomic level materials characterization on highly irradiated and/or radiologically contaminated nuclear reactor fuels and structural materials, where contact handling is not feasible with the high levels of ionizing radiation emitted. Historically, particularly for irradiated nuclear fuel, samples could only be prepared remotely in heavily shielded facilities that precluded the fine contact work needed to prepare usable, let alone high quality, transmission electron microscopy thin foils and atom probe tomography (APT) tips. Thus, most published data on irradiated fuels detail micron level characterization (optical and SEM) and little information is available on nanometer and atomic level structure and chemistry.

Development of a high hertz-stress contact for conventional batch production using a unique scribing technology

Gradually the electronic devices are getting more compact dimension with respect to the width and thickness. As a result, the contacts are becoming thinner and which leads the contact to be loose and unstable contact. In comercial stamping methode, connector tip diameter should be more than 300μm due to its size limitation. Consequently, the connector contact resistance is becoming higher due to weak contact force. To overcome this problem there were few more basic research using MEMS and Electro Fine Forming (EFF) technology to make high Hertz-Stress Contact (5μm) due to the limitation in the commercial stamping process and the result was in satisfactory level. However, since the MEMS and EFF fabrication is costly therefore, a new method is introduced in this paper using the commercial Phosphor Bronze stamping method to reduce the production cost. Moreover, scribing method is used to make tip on the contact. Accordingly, more compact fine pitch contact is successfully fabricated and tested with 5μm High Hertz Stress without using the MEMS and EFF technology. Hence the manufactured contact resistance becomes less than 20mΩ ±5mΩ.

Preparation of Cu2O–Cu anode for high performance Li-ion battery via an electrochemical corrosion method

Cu2O was directly grown on Cu foam via a facile electrochemical corrosion method by the aid of H2O2. Galvanostatic battery testing shows that the Cu2O–Cu electrode exhibits excellent cycle stability and rate capability. It delivers charge and discharge capacity about 0.76mAhcm−2 without attenuation over 100cycles under a charge/discharge rate of 0.15C. After testing at various rates from 0.2 to 35C over 60cycles, the 5th-cycle discharge capacity can resume 98.9% when lowering the charge/discharge rate to 0.2C. The performances are due to both the fine electric contact between Cu2O and Cu foam and a possible porous architecture of Cu2O electrode. The electrochemical reaction kinetic of Cu2O–Cu electrode was studied by cyclic voltammetry measurement at various scan rate, which indicates the anodic and cathodic peak currents show linear dependence on the square root of scan rate from 0.1 to 3mVs−1, suggesting a lithium ion diffusion controlled mechanism in the charge/discharge process.

Fabrication of Cu2S on Cu film electrode and its application in lithium ion battery

Cu2S film electrode direct growth on Cu foil is prepared by a simple hydrothermal approach. The electrochemical properties of the as-prepared Cu2S electrode are investigated via conventional discharge and charge tests. When applying a current density of 0.1mAcm−2, the as-prepared Cu2S electrode exhibits discharge and charge capacity of 0.27, 0.32, 0.35, 0.34 and 0.34mAh cm−2 at the 100th, 200th, 300th, 400th and 500th cycle, respectively. Such good performance of the as-prepared Cu2S electrode is attributed to the fine electric contact between Cu2S and Cu foil and the possible hollow structure of Cu2S film.

Contact detection for nanomanipulation in a scanning electron microscope

Nanomanipulation systems require accurate knowledge of the end-effector position in all three spatial coordinates, XYZ, for reliable manipulation of nanostructures. Although the images acquired by a scanning electron microscope (SEM) provide high resolution XY information, the lack of depth information in the Z-direction makes 3D nanomanipulation time-consuming. Existing approaches for contact detection of end-effectors inside SEM typically utilize fragile touch sensors that are difficult to integrate into a nanomanipulation system. This paper presents a method for determining the contact between an end-effector and a target surface during nanomanipulation inside SEM, purely based on the processing of SEM images. A depth-from-focus method is used in the fast approach of the end-effector to the substrate, followed by fine contact detection. Experimental results demonstrate that the contact detection approach is capable of achieving an accuracy of 21.5 nm at 50,000× magnification while inducing little end-effector damage.

Fabrication of a porous NiS/Ni nanostructured electrode via a dry thermal sulfuration method and its application in a lithium ion battery

A novel dry thermal sulfuration approach has been used to fabricate a porous NiS/Ni nanostructured cathode electrode. Galvanostatic battery testing shows that the NiS/Ni electrode exhibits high discharge/charge capacity and excellent cycle performance. The performances are due to its favorable porous structure and the fine electrical contact between NiS and Ni.

歯当たり検査の自動化に適した近赤外線画像を用いた歯当たり領域の評価手法(機械要素,潤滑,設計,生産加工,生産システムなど)

Tooth contact evaluation has been conventionally performed visually by the machine operator in the gear manufacturing fields when finishing a gear or at assembly. With automation, the boundary of the contact area is unclear due to scattered light when visible light is used to obtain an image to evaluate tooth contact. We have therefore focused on the use of a near-infrared to prevent scattered light. First, a suitable wavelength is investigated to obtain a fine tooth contact image in near-infrared vision. Second, it is confirmed that the tooth contact image obtained by image binarization is hardly affected by the image threshold. Third, we propose a new method to extract the boundary part of the tooth contact by differential calculation of the fine near-infrared image. These methods make it possible to automatically divide a near-infrared image into the contact area, the boundary and the non-contact area. Finally, the obtained result is compared with the tooth contact calculated from the measured tooth surface. As a result, we demonstrated that the near-infrared image method is effective for automatic tooth contact evaluation.

Measurements of thermal effusivity of a fine wire and contact resistance of a junction using a T type probe

The thermal effusivity of a fine wire and the thermal contact resistance of a junction have been measured by a modified T type probe using a periodic heating method. The modified T type probe is made of a short periodic heated platinum wire and a test wire with one end contacting to the midpoint of the hot wire. Dimensionless expressions for the temperature responses of the hot wire with respect to the thermal effusivity of the test wire and the thermal contact resistance of the junction between the test wire and the hot wire were presented. A measurement system based on a flexible resolution A/D board and a LABVIEW-based virtual lock-in was setup. The probe was further verified by measuring four kinds of commercially available metallic wires at room temperature. The obtained thermal contact resistances were repeatable, with the calculated thicknesses of about 1 to 2 microm. The present method can further be applied to measure the thermal effusivity of nonconductive wires, and to analyze the thermal contact resistance of nano/microscale junction.

Systematic Oxidation of Polystyrene by Ultraviolet-Ozone, Characterized by Near-Edge X-ray Absorption Fine Structure and Contact Angle

The process of implanting oxygen in polystyrene (PS) via exposure to ultraviolet-ozone (UV-O) was systematically investigated using the characterization technique of near-edge X-ray absorption fine structure (NEXAFS). Samples of PS exposed to UV-O for 10-300 s and washed with isopropanol were analyzed using the carbon and oxygen K-edge NEXAFS partial electron yields, using various retarding bias voltages to depth-profile the oxygen penetration into the surface. Evaluation of reference polymers provided a scale to quantify the oxygen concentration implanted by UV-O treatment. We find that ozone initially reacts with the double bonds on the phenyl rings, forming carbonyl groups, but within 1 min of exposure, the ratio of double to single oxygen bonds stabilizes at a lower value. Oxygen penetrates the film with relative ease, creating a fairly uniform distribution of oxygen within at least the first 4 nm (the effective depth probed by NEXAFS here). Before oxygen accumulates in large concentrations, however, it preferentially degrades the uppermost layer of the film by removing oxygenated low-molecular-weight oligomers. The failure to accumulate high concentrations of oxygen is seen in the nearly constant carbon edge jump, the low concentration of oxygen even at 5 min exposure (58% of that in poly(4-acetoxystyrene), the polymer with the most similarities to UV-O-treated PS), and the relatively high contact angles. At 5 min exposure the oxygen concentration contains ca. 7 atomic % oxygen. The oxygen species that are implanted consist predominantly of single O-C bonds and double O=C bonds but also include a small fraction of O-H. UV-O treatment leads a plateau after 2 min exposure in the water contact angle hysteresis, at a value of 67 +/- 2 degrees , due primarily to chemical heterogeneity. Annealing above T(g) allows oxygenated species to move short distances away from the surface but not diffuse further than 1-2 nm.

Contact Pressure Dependence of Carrier Mobility in Cleaved Tetracene Single-Crystal Field-Effect Transistors

Tetracene single-crystal field-effect transistors (FETs) were fabricated using fresh cleaved tetracene single crystals. In order to obtain a fine contact between the tetracene crystals and the substrate, a stress was applied using an Instron-type machine. Carrier mobility was measured as a function of applied stress and it was observed that 0.5 cm2/(V s) was the highest mobility under the optimum applied stress.

Effect of Fine Root Contact on Plant-Induced Weathering of Basalt

The objective of the present study was to provide experimental evidence on the active role of plant roots in rock weathering and the importance of the proximity of roots to rock in the weathering process. The analysis was based on the release of different elements from basalt rock particles by three crop species: rice, soybean and maize. Quantitative results were obtained by chemical analyses. We designed two types of hydroponic crop pots, in which fine roots were allowed (or not allowed) to make contact with rock particles by using coarse (or fine) net bags. Experiments were carried out in a controlled glasshouse during a 42 d period. The release of elements in the presence of the plants was calculated by subtracting the decrease in the amounts of elements in the media from the amounts absorbed by the plants. We observed the positive effect of plants on the release of elements from the rock particles and the highest amounts were released in the soybean pots. The amounts of Si, Ca, Mg, Mn and Al released increased by a factor of 2–5, 2–7, 16–112, 3–19 and 6–60, respectively. The amount of Fe released by soybean plants from the rock particles was 4–6 times higher than that by other plants. Between the coarse and fine net pots, the amount of released elements differed significantly only for soybean (Si, Mg and Mn at p < 0.01 level and Fe at p < 0.05 level), which displayed the most vigorous growth. Our results imply that weathering may be caused partially by the absorption of nutrient elements directly through the interface of fine roots and rock particles, and is most likely associated with alterations of the local rhizosphere conditions surrounding the roots.

An Innovative Method for Contact Hole Printing with Binary Mask and Single Exposure

We have introduced a new method for fine contact hole printing using a specially designed binary mask and modified illumination in a single exposure, which can realize k1=0.3 lithography. The binary mask has periodic assist holes around the main holes and the illumination is the combination of strong and weak off-axis parts. Conventionally, assist holes are placed in longitudinal and lateral directions around the main holes or 45° to the main pattern. In this paper, we will show that a new kind of assist hole configuration can be applied to this method and that the new configuration has better imaging characteristics in some cases. Since these three configurations can be utilized with the same illumination, a combination of these configurations in the same mask leads to a wider application of this method because conflicting patterns are avoided.

Performance of CVD diamond alpha particle detectors

The inherent properties of diamond can, in principle, make it an ideal material for radiation detectors with interesting capabilities. We have fabricated a particle detector using a free-standing CVD diamond film with a thickness of 300 μm and area of 2 cm×2 cm and measured 5.5 MeV α spectra from an 241Am source. The I–V characteristics indicate that a fine Ohmic contact is formed between the CVD diamond and electrode. At the external electric field 10 kV/cm, the collection efficiency reaches an average value of 41%, corresponding to a charge collection distance (CCD) of about 259 μm and the energy resolution achieves 4.3%.

Comparative Studies of Perfluorocarbon Alternative Gas Plasmas for Contact Hole Etch

Saturated perfluorocarbons (PFCs) such as CF4, C2F6, C3F8 and c-C4F8 are used as dry-etch gases in the semiconductor industry. They have a significant greenhouse effect. Unsaturated fluorocarbons can be alternated with these PFCs because of their easy decomposition in the atmosphere. The authors have diagnosed the plasmas generated from straight-chain unsaturated gases such as C3F6, C4F6, C4F8 and C5F8 in an inductively coupled plasma reactor and have compared their etch properties. It was found that high selectivity has been obtained in a C4F6 or C5F8 plasma without mixing any specific gases. Fine contact holes of approximately 100 nm in diameter also have been obtained using C4F6 or C5F8 with or without adding Ar or O2. These good etch properties of C4F6 and C5F8 have been achieved as a consequence of the appropriate balance between the lower density of fluorocarbon polymers and the dominant etching species CF+ with lower etching efficiency. It can be concluded that C4F6 and C5F8 can be used as PFC replacements for the dry-etch gas.

Preflashover and flashover phenomena of silicon–vacuum system under pulsed excitation

Rectangular n+nn+-type silicon blocks with different surface treatments, i.e., one surface is chemically etched and the other is unetched, were used to investigate the characteristics of preflashover and flashover of semiconductor under a high voltage pulse in a vacuum. The metallic contacts were employed to keep a fine contact between the sample and the electrode. For unetched samples, the preflashover current obeyed Ohm’s law, and for etched samples, it was dominated by the space-charge limited current. After flashover shots, two kinds of silicon samples showed quite distinct tracks. It is considered that all the phenomena are attributed to the different density and distribution of surface states for two kinds of samples. The developing process of surface flashover across a semiconductor could be explained as the current filamentation which is induced by thermal effects. It is suggested that the flashover occurs in the interface layer of silicon butted to electrodes, and in the lateral layer of silicon near the vacuum ambient with a depth of ∼2 μm.

Optical studies of surface discharge under dc voltage in vacuum

Utilizing a high-sensitivity photomultiplier tube (PMT) and an intensified charge coupled device (ICCD) camera, the light emission from the surface of polytetrafluoroethylene (PTFE) and alumina ceramic samples was investigated in vacuum under a stepped dc voltage in order to study the initiation and development of surface discharge. Different from the classical electrode contact by butting electrodes on a sample directly, to achieve a fine contact between electrodes and the surface of a sample, the metalized electrodes were employed by sputtering two additional gold contacts on each sample in advance. The two types of materials showed quite different optical characteristics. It was suggested that there were several processes possibly related to the initiation mechanism of the surface discharge. Besides the field electron emission from the cathode triple junction (CTJ) for the classical electrode contact, there were charge injection and transport in the surface states of dielectrics, and charge trapping and detrapping phenomena. Electroluminescence (EL) emission was emitted due to the radiative recombination of electrons and holes injected. These processes were strongly dependent on the electrode contact manner and the surface states of insulating materials.

Constraint network analysis of 3-dimensional insertion tasks

Flexible assembly machines may be improved and costs reduced by relaxing constraints on part fixturing accuracy and employing compliant devices in assembly effectors. An effector-mounted remote center compliance device that corrects for spatial misalignments of prismatic parts of general cross section has recently been demonstrated. This “spatial RCC” was designed by planning for the possible fine motion assembly contact states given a range of initial position and orientation uncertainty between the mating parts. These fine motion contact states are arranged in a constraint network in the fashion of a Petri net controller, however, the control transitions are mediated by compliances reacting to contact forces rather than from force sensing and discrete event controller schemes. A path through the constraint network of a square peg and hole task is found from initial to final assembly states. This path defines a single compliance relationship that is realized with a practical assembly device. Extensions of this design technique to other assembly tasks are discussed.

Epitaxial Si 1− x Ge x grown into fine contact hole by ultrahigh-vacuum chemical vapor deposition

An ultrahigh-vacuum chemical vapor deposition technique with disilane (Si 2H 6) and germane (GeH 4) molecular flux is applied to Si 1− x Ge x ( x=0–0.15) selective growth into fine contact holes. The growth behavior of epitaxial Si 1− x Ge x layer is influenced by addition of GeH 4 with Si 2H 6 flow rate kept at constant, which is interpreted by estimation of facet growth rates. The growth rates of (311) and (111) facets are drastically decreased by addition of a small amount of GeH 4. As a result, in the fine holes, the epitaxial layer height of Si 1− x Ge x is limited by the (311) growth rate and decreased compared with pure Si.