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

Optical properties of vacuum-deposited silver films have been investigated by ellipsometry. A method of calculating optical parameters has been developed and applied to this investigation. On the assumption that the film is optically isotropic, n, k, and d are simultaneously determined by the measured values of ψ, Δ, and the transmittance of p-polarized light. For very thin films, those isotropic parameters show an anomalous behavior, and for thinner films, the computation for determining them does not converge. The computation converges only when the optical anisotropy of the film is taken into account, and the convergent range of the anisotropic parameters is determined. The convergence range includes the anisotropic parameters predicted by the theory for the optical properties of an aggregated silver film. An anomalous increase of the isotropic parameters with decrease of thickness, for thinner films, arises from regarding the anisotropic film as isotropic.

Effects of Optical Anisotropy of Aggregated Silver Films on Ellipsometric Determination of n, k, and d

The strain effect on the electrical conduction in discontinuous gold films

PTFE foils were plasma-treated in order to enhance their adhesion to thin films The effect of plasma treatment using argon and oxygen discharge gases on the surface energy of PTFE foils was examined by measuring the contact angles of water droplets placed on the foil surface Exposure to the plasma for only about 10-20 s was very effective in enhancing the surface energy By depositing gold films onto the PTFE substrates, it was found that this enhancement in surface energy was directly related to an increase in the film adhesion It was also found that Ar plasma treatment of a few tens of seconds followed by O2 plasma treatment for 10 s was even more effective for adhesion enhancement

Akira Kinbara

Papers

Effects of Optical Anisotropy of Aggregated Silver Films on Ellipsometric Determination of n, k, and d

The strain effect on the electrical conduction in discontinuous gold films

Effect of plasma treatment of PTFE substrates on the adhesion characteristics of vacuum-deposited Au films

Adhesion measurement of non-metallic thin films using a scratch method☆

Crystallization of amorphous antimony films