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.

Thin Film Materials: Stress, Defect Formation and Surface Evolution

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.

Electrical and optical properties of TiO2 anatase thin films

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.

Ultrafine metal particles

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.

https://iopscience.iop.org/article/10.1088/0953-8984/4/5/001/pdf

Surface-enhanced Raman scattering

Metasurfaces: From microwaves to visible

Double layered structures consisting of soft (S-) metal (Au, Ag, Cu, Al) films and hard (H-) metal (Cr) film were formed onto glass (G-) substrates by vacuum evaporation method. The adhesion characteristics of those structures were investigated by using the scratch tester developed by the present authors.In case of S/H/G structures, the scratch peeling in the process of increasing loads was found to have two steps. Namely, S-film peeling at the S/H interface is occurred by comparatively small peeling loads followed by the H-film peeling at H/G interface by a larger load. On the other hand, the peeling of H/S/G structures has only one step. By applying a enough load to break the H-film, the double layers were peeled off at a time at the S/G interfaces.The mechanism of the scratch peeling is discussed.

Adhesion Measurement of Evaporated Films of Laminate Structure

High Power Examinations of RF Window Materials

Measurements of Thickness and Sputtering Yields of Thin Films Using a SAW Device

Adhesion of optical coatings on a quartz substrate

Thermal expansion of vacuum deposited gold films being free from substrate was measured in a specially designed furnace by using a slide cathetometer from room temperature to 300°C. It was found that in lower temperature region (below 250°C) there was no appreciable difference between the thermal expansion of gold films and that of bulk gold. However, in higher temperature region (above 250°C), especially in case of relatively thinner films, the aspect of the thermal expansion drastically differed from that of bulk, that is, the contraction of film length was observed. The origin of the contraction was discussed from the viewpoint of the change of film structure due to heating.

Akira Kinbara

Papers

Adhesion Measurement of Evaporated Films of Laminate Structure

High Power Examinations of RF Window Materials

Measurements of Thickness and Sputtering Yields of Thin Films Using a SAW Device

Adhesion of optical coatings on a quartz substrate

Thermal Expansion of Evaporated Gold Films