Akira Kinbara

Bio: Akira Kinbara is an academic researcher from University of Tokyo. The author has contributed to research in topics: Thin film & Sputtering. The author has an hindex of 26, co-authored 116 publications receiving 2211 citations.

Adhesion measurement of Ti thin films on Si substrate using internal stress in overcoated Ni films

Abstract: Adhesion strength between sputtered Ti thin films and Si substrate has been evaluated by using an internal stress in Ni thin films deposited onto the Ti thin films. The adhesion of the Ni film to the Ti film is very strong and the internal stress in the Ni film was found to be large enough to peel off the Ti film from the Si substrates. The tensile stress generated by the internal stress in the Ni film at the interface between the Ti film and the Si substrate was evaluated by finite element method. By this method, it became clear that when the value of the Ni film internal stress times the Ni film thickness was 150 N/m, the corresponding tensile stress at the interface was 10 MPa and this stress was enough to peel off the Ti film on an Ar ion bombarded Si substrate.

Time-dependent O2 mass balance change and target surface oxidation during mode transition in Ti–O2 reactive sputtering

Abstract: Time-dependent O2 mass balance change among the amounts injected into the chamber, pumped out from the chamber, gettered by sputtered Ti metal, residing in the chamber, and consumed to oxidize the target surface has been investigated as a function of time elapsed after the discharge ignition in Ti–O2 reactive sputtering. From the mass balance results obtained, target surface coverage has been estimated. In the period of up to 10 s after discharge ignition, the gettering of O2 by sputtered Ti dominated the process change. In this period, the target surface oxidation rate was low. In the period of 20–50 s, the amount of O2 consumed to target surface oxidation surpassed the amount of O2 gettered by deposited Ti, resulting in a drastic increase in the target coverage. After the target surface oxidation was completed, the process became stable. In this period, the amount of O2 pumped out without causing any process changes increased and a very small amount of O2 was consumed to oxidize the target surface. The ...

Thin Film Materials: Stress, Defect Formation and Surface Evolution

Abstract: 1. Introduction and overview 2. Film stress and substrate curvature 3. Stress in anisotropic and patterned films 4. Delamination and fracture 5. Film buckling, bulging and peeling 6. Dislocation formation in epitaxial systems 7. Dislocation interactions and strain relaxation 8. Equilibrium and stability of surfaces 9. The role of stress in mass transport.

Electrical and optical properties of TiO2 anatase thin films

Abstract: Electrical and optical spectroscopic studies of TiO2 anatase thin filmsdeposited by sputtering show that the metastable phase anatase differs in electronic properties from the well‐known, stable phase rutile. Resistivity and Hall‐effect measurements reveal an insulator–metal transition in a donor band in anatase thin films with high donor concentrations. Such a transition is not observed in rutile thin films with similar donor concentrations. This indicates a larger effective Bohr radius of donor electrons in anatase than in rutile, which in turn suggests a smaller electron effective mass in anatase. The smaller effective mass in anatase is consistent with the high mobility, bandlike conduction observed in anatase crystals. It is also responsible for the very shallow donor energies in anatase. Luminescence of self‐trapped excitons is observed in anatase thin films, which implies a strong lattice relaxation and a small exciton bandwidth in anatase. Optical absorption and photoconductivity spectra show that anatase thin films have a wider optical absorption gap than rutile thin films.

Ultrafine metal particles

Abstract: In this paper we present a novel and versatile t e c h n i q u e f o r t h e p r o d u c t i o n o f u l t r a f i n e m e t a l p a r t i c l e s by evaporation from a temperature‐regulated oven containing a reduced atmosphere of an inert gas. An extensive investigation of particles of oxidized Al, with diameters of 3 to 6 nm, has been performed. We have also studied ultrafine particles of Mg,Zn, and Sn produced in the same manner. A supplementing investigation has been carried out for particles of Cr, Fe, Co, Ni, Cu, and Ga, as well as larger Al particles, produced by ’’conventional’’ inert‐gas evaporation from a resistive filament. Diameter as a function of evaporation rate, inert‐gas pressure, and the kind of inert gas are reported. Crystalline particles smaller than 20 nm look almost spherical in the electron microscope, while larger ones often display pronounced crystal habit. S i z e d i s t r i b u t i o n s have been investigated in detail, and consistently the logarithm of the particle diameter has a Gaussian distribution to a high precision for the smallest sizes, whereas larger particles deviate from such a simple behavior. A statistical growth model, based on the Central Limit Theorem, has been formulated for liquidlike coalescence of particles; this theory accounts satisfactorily for all our data, as well as for most size distributions published in the literature. Applications of the model to colloids, discontinuous films, and supported catalysts are discussed. By comparing size distributions for particles produced by a variety of techniques we found a number of empirical rules for the width of the distributions, as defined by a (geometric) standard deviation σ. For crystalline inert‐gas‐ evaporated particles we obtained consistently 1.36?σ?1.60; for coalescing islands in discontinuous films we found 1.22?σ?1.34; and similar rules are applicable to colloids, supported catalysts, and to ultrafine droplets.

Surface-enhanced Raman scattering

Abstract: On the basis of different types of experiments, the authors develop implicitly the model of surface-enhanced Raman scattering (SERS) of adsorbates on metal surfaces. The long-range enhancement by resonances of the macroscopic laser and Stokes field is separated quantitatively from the metal electron-mediated resonance Raman effect. The latter mechanism proceeds by increased electron-photon coupling at an atomically rough surface and by temporary charge transfer to orbitals of the adsorbates. This model can account for the chemical specificity and vibrational selectivity of SERS and (partly) for the SERS specificity of the various metals.