Super Thin Film Research Articles

Transparent, Stretchable and Direct Skin-Touchable Multi-Functional Electronic Skin Sensors

Multi-functional electronic skin (e-skin) sensors, which can be directly skin-attachable to human body for normally monitoring the outside illumination environment and the movement situations of human body, can play a vital role in personal health and body rehabilitation. However, multi-functional e-skin sensors with transparency, stretchability, and skin-attachable to human body still keep challenge. In this paper, an optical transparent, low resistivity, good flexibility, light-sensitivity, and biocompatible multilayer film e-skin sensor was fabricated with the interpenetrating networks containing the silver nanowire (Ag NW) and the azobenzene buried in between silk fibroin (SF) film and poly (dimethylsiloxane) (PDMS) film. The multilayer film e-skin with thickness of 150 μm can light a light-emitting diode (LED) chip under direct current, and the super thin SF film of the e-skin sensor can provide good biocompatibility for human skin due to similar human skin protein structures, and the interpenetrating networks containing the silver nanowire (Ag NW) and the azobenzene can produce an obvious response for UV illumination, human body bending and/or uniaxial tensile. Moreover, the three-sublayer-structured e-skin is low-cost, less equipment-intensive, and easily mass-produced, and be widely used in commercial applications of medicine, bionic-robot, and other wearable electronics.

Influence of the thermal effect on the cutting forces in the ultrasonic machining of high-strength materials

A method is proposed for determining the frictional force at the tool’s cutting surface in the ultrasonic machining of high-strength materials. The formation of a superthin soft surface film under the tool tip on account of the thermal effect is taken into account.

Passage of a charged particle through a thin solid film

The inelastic collisions effect on the interaction of the projectile with a super thin solid film is considered. The wave nature of the particle and its transitions from delocalized to the strongly localized state defined many important properties of the interaction. As examples the effect of perforation the 1nm carbon foil as well as the overwhelming passage through a thick porous layer are considered.

Charge Collection Characteristics of A Super-Thin Diamond Membrane Detector Measured With High-Energy Heavy Ions

A transmission particle detector based on a super-thin diamond membrane film which can also be used simultaneously as a vacuum window for ion beam extraction has been developed. Charge collection characteristics of a 6.8 μm-thick diamond membrane detector for high-energy heavy ions including 75 MeV Ne, 150 MeV Ar, 322 MeV Kr, and 454 MeV Xe have been investigated for the first time. Charge collection signals under single particle flux from the thin part are stable and are well distinguishable from background signals. This behavior suggests that the diamond membrane detector could be used for counting single ions. On the other hand, charge collection efficiency is found to decrease with increasing of charge generated in the diamond membrane detector. This suggests that the pulse height defect, which has been previously reported for Si and SiC detectors, also occurs in the diamond membrane detector.

Gravitational flow of a thin film of liquid metal in a strong magnetic field

The influence of a poloidal magnetic field of the spherical Tokamak on super thin (h≈0.1mm) film flow of liquid metal driven by gravity over the surface of the cooled divertor plate is addressed. The experimental setup developed at the Institute of Physics, University of Latvia (IPUL) is described, which makes it possible to drive and visualize such liquid metal flows in the solenoid of the superconducting magnet “Magdalena”. As applied to the above setup, the magnetic field effect on the operation of the capillary system of liquid metal flow distribution (CSFD) is evaluated by using molten metal (lithium or eutectic InGaSn alloy) with a very small linear flowrate q≤1mm2/s, spread uniformly across the substrate. The magnetic field effect on the main parameters of the fully developed film flow is estimated for the above-mentioned liquid metals.An approximation technique has been proposed to calculate the development of the gravitational film flow. A non-linear differential second order equation has been derived, which describes the variation of the film flow thickness over the substrate length versus the flowrate q, magnetic field B and the substrate sloping α.Results of InGaSn film flow observations in a strong (B=4T) poloidal magnetic field are presented. Analysis of the video records evidences of experimental realization of a stable stationary film flow at width-uniform supply of InGaSn.

Modeling and Analysis of Micro Hybrid Gas Spiral-Grooved Thrust Bearing for Microengine

The micro hybrid spiral-grooved thrust bearing is a promising candidate to support the rotating elements in power MEMS devices such as micro gas turbine engines. However, the realization of hybrid thrust bearings has encountered a number of technical challenges due to the very high rotating speed and DN number (the product of the inner diameter and the rotational speed of the bearing, mm · rpm) to achieve high power density, the super thin gas film between rotors and thrust pad, and the relative large fabrication uncertainties according to the imperfection of the fabrication technology. In this paper, the configuration of a micro hybrid spiral-grooved thrust bearing for power MEMS is designed, and the steady and dynamic characteristics of this kind of bearing are then analyzed comprehensively, with the consideration of both the rarefaction effects and the influence of potential microfabrication defects. The nonlinear equations of molecular gas-film lubrication describing the gas rarefaction effects in a micro hybrid bearing are discretized by the finite volume method and solved by the Newton–Raphson techniques. The small perturbation technique is employed to study the dynamic behavior of a micro hybrid bearing. The results show that the micro hybrid thrust bearing exhibits better steady-state and dynamic performance than the existing micro hydrodynamic and hydrostatic bearings and that the hybrid bearings are likelier to be stable than their hydrodynamic counterparts, especially when the frequency number is high. The load capacity of the micro hybrid bearing increases slightly with the number of orifices and gradually with the diameter ratio of the orifice. The microfabrication defects of clogged orifices could lessen the load capacity and the dynamic coefficients of the hybrid thrust bearing. The model developed in this paper can serve as a useful tool to provide insight into micro hybrid gas thrust bearing-rotor systems.

The Formation of Super-Thin Dielectric Film on Porous Substrate and its Stopping – Transmittance Characteristics for Particles

The formation of super-thin continuous dielectric film (e.g. the ion barrier film-IBF) on microchannel plate (a kind of porous substrate) is most important for prolonging the operating life of the third generation micro-light image tube. In this paper, firstly, the formation of Al2O3 ion barrier film on microchannel plate (MCP) using a new contamination-free technology was introduced. According to the analysis and the comparison with the traditional direct formation technology, it was found that the productivity of the new technology is better (90%) and the carbon contamination can be minimized. Next, the stopping and transmittance characteristic of the film for electrons were studied and the measurement principle was shown. In this measurement, the concepts of “dead-voltage” and “electron transmittance” were proposed to evaluate the stopping and transmittance of the film for electrons. The dead-voltage was 220V for the MCP covered the ion barrier film with a thickness of 5nm and the electron transmittance was over 90%.

Surface morphology and electrical property evolution of super-thin Pt film on 6H-SiC substrate during annealing

We reported the surface morphology and electrical property of super-thin Pt films, ∼2 nm thick, deposited on 6H-SiC (0001) substrates and subsequently annealed from 400 to 1000 °C. The surfaces of the films were found to have a feature of islands growth, and the sizes of the islands increased with increasing annealing temperature. Free carbon, produced by selective reactions between Pt and SiC, diffused toward the top surface across the product layers due to low solubility and composition gradient of carbon throughout the reaction zone. A dramatic change of electrical conductivity of the films was observed. A mechanism analysis reveals that the origin came from the contribution of aggregation of islands on the surface and formation of Pt silicides and a thin layer of crystalline graphite.

Corrosion Resistance and Structure of Thiol Self-assembly Super Thin Film on Zinc Coated Steel Sheet

Thiol self-assembly super-thin films have attracted considerable attention for molecular-level surface design as in chemical sensors, molecule-based devices and corrosion resistant films. Meanwhile, chromate coatings on zinc coated steel sheets are widely used as an economical method of preventing corrosion. In response to recent environmental regulations, such as the RoHS Directive, chromate-free coatings have been developed and applied to electrical appliances. However, a thinner coating is required to obtain better electroconductivity, which influences the electromagnetic shielding performance of digital electrical appliances. In this study, we investigated the corrosion resistance and film structure of alkanethiol and triazinethiol self-assembly super thin layers on zinc coated steel sheets. The corrosion inhibition mechanism of the thiol layers was discussed in order to develop a new design concept for thinner chromate-free coatings with high corrosion resistance. The alkanethiol layers showed high water repellency and poor corrosion resistance, and the triazinethiol layers with three thiol groups per molecule showed relatively poor water repellency and excellent corrosion resistance despite the very small thickness (several monolayers), as a result of suppressed oxygen reduction reaction determined by electrochemical measurement. XPS analysis revealed that alkanethiol molecules adhered to the zinc and formed layers with no decomposition, and triazinethiol molecules adhered to the zinc and then partially decomposed and reorganized to form a new network structure.

Interposition fixing structure of TiO 2 film deposited on activated carbon fibers

The immobilized photocatalyst, TiO 2 film supported on activated carbon fibers (TiO 2/ACFs) prepared with molecular adsorption-deposition (MAD), exhibits high stability in cyclic photodegradation runs. The interposition fixing structure between TiO 2 film and carbon fiber was investigated by means of SEM-EDX, XRD, XPS and FTIR, and a model was proposed to explain this structure. With SEM examination of carbon fiber surface after removing the deposited TiO 2 film, a residual TiO 2 super-thin film was found to exist still. By determining surface groups on ACFs, titanium sulfate (Ti 2(SO 4) 3) in burnt remainders of the TiO 2/ACFs was thought to be formed with an interfacial reaction between TiO 2 film and carbon fibers. These provide some evidence of firm attachment of TiO 2 film to carbon fiber surface. In the consideration of characteristics of the MAD, the deposition mechanism of TiO 2 film on ACFs was proposed, and the interposition fixing structure was inferred to intercrossedly form between TiO 2 film and ACFs' surface. This structure leaded to firm attachment and high stability of the TiO 2 film.

Study of deposition of super thin Fe film on NiO(001) substrate

One to ten Fe monatomic layers (ML) with wedge-shape were deposited on the NiO(001) substrate by molecular beam epitaxy (MBE) and pulsed laser deposition (PLD), respectively. The analysis in situ of surface magneto-optic Kerr effect indicates that the Fe layer gives rise to an about 2ML thick magnetic dead layer at the interface of Fe/NiO by MBE deposition. The magnetic dead layer is about 3ML for the method of PLD. X-ray photoelectron spectroscopy indicates that both ways of deposition can lead to interfacial chemical reactions.

超金属調メタリックシルバーを実現する超薄膜塗装技術

超金属調メタリックシルバーを実現する超薄膜塗装技術

Improvement of the Response Time of Super Thin Film Transistor Liquid Crystal Displays by Using a Backlight System

To enable application to full moving images, the response time of liquid crystal displays (LCDs) must be improved. In this paper, we will discuss our results of improving the response time using the blink backlight system. When the display image changes from black to white, the lamp turns on after the rise of the LCD response. On the other hand, when the display image changes from white to black, the lamp turns off before the LCD response falls. The total response time of the super thin film transistor (TFT)-LCD was improved from 25 ms to 8 ms, which corresponded to the lamp response time. Moreover, the response time was dependent on the fluorescence wavelength of the lamp material. The blue fluorescent lamp (CFL) material has the fastest response time, 2 ms. If the response time of green and red fluorescent materials can be improved similarly to the blue one, it will be possible to obtain a moving picture quality comparable to that of a cathode-ray tube.

Formation of a super-thin film and a self-assembly cellular sheet by ion-beam irradiation

We performed ion-beam irradiation of biodegradable polymer sheets to develop a super-thin film and self-assembly cellular sheets, which exfoliated spontaneously from the substrate in a water solution. Poly- l-lactic acid sheets were used as substrates. We performed He + and Kr + ion-beam irradiation at energies of 50, 100 and 150 keV with fluences between 1 × 10 14 and 1 × 10 15 ions/cm 2. He + ion-beam irradiation formed a super-thin film at an energy of 50 keV with a fluence of 1 × 10 15 ions/cm 2 and thickness of 500 nm. Kr + ion-beam irradiation did not form a film. Simultaneous He + and Kr + ion-beam irradiation improved cell attachment properties. We obtained self-assembly cellular sheets by combining these two techniques. The film thickness can be controlled by controlling the ion species and acceleration energy. The experimental values agreed well with the theoretical results. This technique should be useful for new medical devices.

Superthin polymeric film and its application in optics

The results of the properties investigation and application of the superthin polymeric film (0.1–0.4 μm thickness) are discussed. The strong film with too small thickness without the substrate (pellicle membrane) has not been produced earlier. There are a lot of areas for the superthin film application in an engineering and science. The application field of the most importance is their use as a beam-splitter in Fourier transform spectrometer (FTS) “double cat’s eye” and in laser Tviman-Grin interferometer.

Near-field effect in a superthin film of resonance atoms

A boundary-value problem of nonlinear resonance optics in the interaction of intense light with a superthin film of two-level atoms is solved. In solving this boundary-value problem, the authors draw on the idea of a discrete-continuous system in which the atoms are distributed in a discrete manner in the vicinity of the point of observation. It is shown that detailed account of the dipole field leads to a near-field effect both inside the film and outside it in the near zone with respect to outer film surfaces. Various properties of the near-field effect in stationary irradiation of the film with quasi-resonance radiation with allowance for a resonance shift are investigated. It is shown, in particular, that, in the near zone, there is a nonexponential dependence of the fields of reflected and transmitted waves on the coordinate of the point of observation.

Design and technology features of heating-free magnetrons with autoemission excitation

Design and technology of a heating-free magnetron cathode with autoelectron and secondary electron emitters are presented. It is reported that there is a high electric field concentration on an edge of a super thin metal film. Pulsed volt–ampere characteristics of activated and deactivated emitters and their reciprocal transitions are shown. Main characteristics of heating free magnetrons with 10, 25, and 50 kW pulse output power are tabulated.

Determination of layered synthetic microstructure parameters

A method for determining the parameters of real layered synthetic microstructures (LSMs) of superthin films (the layer thickness is about 1–10 nm) is discussed. This method is based on the analysis of small angle X-ray diffraction spectra ( λ≈0.1 nm). The following LSM parameters have been determined: (1) concentration of atoms in the layers; (2) thickness of the layers and thickness of the interface between the LSM constituent layers; (3) characteristics of the layer thickness fluctuations. The Ni-C and Ni-Ti structures serve to illustrate the method. The potentialities of this technique in superthin film growth and diffusion investigation are demonstrated.

Advanced Superthin Polysilicon Film Obtained by Si+ Implantation and Subsequent Annealing

The random solid‐phase grain growth behavior of Si+‐implanted very thin silicon films and its related electronic properties have been investigated. Si+‐implanted disordered silicon films showed variable range hopping conduction and high electron spin resonance (ESR) center density of more than 1019/cm3. Two‐dimensional dendritic crystal grains grew with subsequent furnace annealing at 600°C. Nucleation time retarded for the increase of Si+ dose. Maximum grain size of 5 μm was obtained. Moreover, remarkable photoconductivity was seen and films changed to activated type of conduction after polycrystallization. We have fabricated a superthin film transistor using these films and obtained field effect electron mobility more than 100 cm2/V · s. Mobility value depended on grain size, i.e., the Si+ dose that corresponded to the ESR center density in disordered Si+‐implanted films.

A negative drain conductance property in a super-thin film buried-channel MOSFET on a buried insulator

A negative drain conductance property in buried-channel MOSFET's on a buried insulator is demonstrated experimentally. The physical origin of the negative drain conductance is discussed theoretically. It is shown by a numerical analysis that the diffusion current of majority carriers, which flows against the drift current, is the origin of the negative drain conductance beyond the pinchoff stage. It is indicated that an intensely high convex profile of majority carriers near the drain is essential for that diffusion current, and that the profile is easily achieved when the conductive layer thickness is less than an extrinsic Debye length.