Attempts made on the gradient control of functional properties for electroless deposited magnetic thin films were overviewed to introduce the methodology for the preparation of functionally graded thin films by means of electrochemical processes. By use of appropriate ultra-thin underlayers, the coercivity, Hc, of electroless CoNiP films was controlled toward the film thickness direction. Sequential control of the rotating speed of substrates during the deposition enabled the programmed control of the gradient of Hc. These procedures could be useful tools for optimizing graded magnetic properties of the films used in various magnetic devices. The tools are expected to be widely applied to fabricate various kinds of films with functionally-graded properties.
Fine platinum (Pt) particles were electrodeposited on n-type silicon (n-Si) electrodes from an aqueous hexachloroplatinic acid (IV) solution by single potential step and double potential step (DPS) methods. The distribution density of the Pt particles on the electrode increased from 109 to 1010 cm−2 as the pulse potential at the initial step of the DPS method decreased from −1 to −4 V vs. SCE. The size of the Pt particles became larger with increasing the electricity passing across the electrode surface. Photoelectrochemical solar cells equipped with Pt-electrodeposited n-Si electrodes generated open-circuit photovoltage of 0.6 V and provided an energy conversion efficiency of 10%. Solar cell characteristics changed with the size and distribution density of the Pt particles.
Organosilane self-assembled monolayers (SAMs) have been applied to photoresists in a photolithography using vacuum-ultraviolet (VUV) light at 172 nm in wavelength. Although SAMs consisting only of alkyl chains are not photosensitive to UV lights used in conventional photolithographies, micropatterning of such SAMs were achieved through the dissociative excitation of the organic molecules and the subsequent oxidation reaction with activated oxygen species generated by VUV irradiation of atmospheric oxygen. Since this VUV photolithography is based on the photodecomposition of carbon-carbon bonds, the method, in principle, will be applicable to any organic thin films. Furthermore, pattern transfer techniques by the use of wet processes, that is, chemical etching, electroless plating and spatially regulated growth of mesostructured silica film, have been demonstrated.
Printed circuit boards used in many electronic parts are fabricated by photolithography, where copper foil attached to organic material boards is etched locally to produce fine patterns. The authors introduce an innovative method for the fabrication of printed circuit boards, using anodizing, laser irradiation, and electro-plating or electroless-plating. Aluminum foil with anodic oxide coating is immersed in solutions containing metal ions, and then irradiated with a pulsed Nd-YAG laser through a convex lens. Laser irradiation removes the oxide film locally and allows metal particles to be deposited by redox reactions on the portion. Thus electro-plating or electroless-plating is possible over the metal particles at the laser irradiated area. An organic resin is bonded to the aluminum foil to remove the aluminum substrate by dissolving in alkaline solutions. The procedure described above provides a pattern with 9 µm line width and 12 µm interval.
Anodization technology used in LCDs (Liquid Crystal Displays) is reviewed. The wet anodization process has an advantage over other dry processes to produce thin oxide films with very smooth surface and less pinholes. Aluminum or its alloy gate lines used in some TFT (Thin Film Transistor)-LCDs are covered with anodic oxide thin films to prevent their hillock formation and corrosion. On the other hand, anodic oxide films of tantalum or its alloys are also used as an insulator of non-linear switching elements in TFD (Thin Film Diode)-LCDs. Anodization is carried out in aqueous or nonaqueous electrolyte solutions. However, only limited electrolyte solutions have been used for manufacturing TFT-LCDs. Here, we introduce our recent results on the anodization of sputtered Al-Nd alloy films in ethylene glycol - based nonaqueous electrolyte solutions.
Small Si islands and atomic steps on Si(111)7×7 have been observed by scanning tunneling microscopy (STM). At the edges of both structures, we observed characteristic elliptic double protrusions in the STM images. We have proposed atomic structural models of the islands and steps. Partial collapse of the islands during STM observation is well explained by the proposed model. It is concluded that the double protrusions are caused by the distortion of the 3×3 half unit-cell (HUC) of the dimer-adatom-stacking fault structure. This HUC has a specific structure that only one side of the triangular HUS is connected with a neighboring 3×3 HUC.
Adhesion tension can be determined using the potential theory that the total energy of the drop on a plate is minimized. In order to calculate the energy of the drop, it is necessary to find a fitting curve that indicates the precise drop profiles in video image. In this study, a precise numerical curve-fitting method of sessile drop profile is proposed, which is based on the geometrical boundary conditions for Laplace equation derived from the approximate curve of the drop by video image processing. It is found that the proposal solution fits the profile of measuring pure water drops in the video image processing.
A novel surface sensitive experimental method, “X-ray traveling wave”, is proposed. This method utilizes the total reflection of X-rays. Many difficulties are in principle arising in this method. To avoid these difficulties, it is described that the wave guide technique is useful. Errata of equations presented in published papers by the present author and others are described. The details of the total reflection of X-rays are qualitatively described using illustrations. The traveling wave can be detected when the surface is coated by thin layers in such a way that the reflected X-rays are annihilated due to the phase inversion.