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

Crystal structure, dynamic hardness and internal stress of compositionally modulated Ti-TiN multilayer films were examined in order to discuss the mechanism of hardness enhancement by compositional modulation. The hardness of the films showed a sharp peak at10 nm and was larger than that of a monolithic TiN film. XRD patterns of the films with short modulation periods showed peaks assigned to TiN single phase. With increasing the modulation period to 20 nm, XRD peaks assigned to TiN phase were broadened and weakened. Further increasing the period, broad peaks assigned to Ti were emerged. Compressive stress, which causes the films hardened, was observed in monolithic Ti and TiN, and compositionally modulated Ti-TiN films. Energy dissipated ratio defined as the ratio of dissipated energy to applied energy showed the minimum at the modulation period of 10 nm, indicating that plastic component of the deformation energy decreased. Reduction of the plastic component at the modulation period of 10 nm was in good agreement with results obtained by the hardness measurement. Decreasing of the plastic component strongly suggests that TiN layers, which has a high elastic modulus, plays an important part in the plastic deformation of the films at short modulation period.

https://www.jstage.jst.go.jp/article/jvsj1958/42/7/42_7_657/_pdf

Hardening Mechanism of Compositionally Modulated Ti-TiN Multilayer Films

高 エネルギ ー物理学研 究所 ・放射光入射器の電子線形 加速器 では,大 電力 クライス トロンの出力部及び導波管 途 中に アル ミナセ ラ ミック高周波窓 が用 い られ ている が,大 電力使用時にマルチパ クタ リング等 によ り破壊す る ことが問題 とな った1).こ の問題 に対 し,破 壊の原因 である二次電子放出及びマルチパ クタ リングを抑制する ため,5nm程 度のTiNコ ーテ ィングを施 こす事で成果 を挙げている2). TiN薄 膜 は直流 スパ ッタ法で アル ミナセ ラ ミック上 に コーテ ィングされ,膜 厚 モニター(水 晶振動子)で 見 る限 り極めて安定 である.コ ーティング前後,同 一 容器 内 でAES観 察 が行われ るが,絶 縁体 に特徴 的な帯電 が 問題 とな る.特 に,TiN薄 膜 コーテ ィング後 はそ の目 的 の通 り全二 次電子 放出係数 σが1以 下 となる一次電 子エネルギーが広範 囲 となるため,負 の帯電に よる表面 電位が数kVに 及 ぶ こともあ り3)AES観 察は困難 となる 場合 が多い.負 の帯電 を避 け るため に,AESの 一次 電 子 エネルギ ーを低 くして も良好 なAESス ペ ク トルは得 られなか った. AESに 代 わ る表面 分析手段 として,AES装 置を その まま用い ることができ,し か も以下 に述べ る理由で帯電 の影 響 を 受 け 難 い エ ネ ル ギ ー 損 失 分 光(ELS: Energy

AES and ELS measurements of TiN/Alumina ceramics

Adhesion measurement of thin films on glass substrates by scratch method

Self-bias potential and its distribution of a radio-frequency (RF) electrode have been measured in argon and helium plasma using probes penetrating the electrode. In the absence of the magnetic field the self-bias potential distribution is almost homogeneous at-150 V (RF power = 26 W) in Ar plasma. When the magnetic field (B =0.04 T) parallel to the electrode is applied, the mean value of the potential is reduced to-40 V and the gradient in the potential distribution occurs along the E× B direction. Rotation of the magnetic field at a frequency below 50 Hz is unable to reduce potential inhomogeneity, but this technique enables us to measure the potential distribution as a continuous function of the azimuthal angle. In helium plasma, another type of inhomogeneity parallel to the magnetic field occurs; this inhomogeneity can be reduced effectively by pulsed Ar gas injection. These data are discussed to show physical meaning and industrial applications.

Studies of the Distribution of the Self-Bias Potential on an RF Electrode in Plasma

The crystallization of amorphous metal oxide thin films was achieved by RF plasma treatment. Although various amorphous films are crystallized after 3 minutes or so, the sample temperature is lower than 150 degrees C without compulsory cooling even when the films are treated for 1 hour. The oxygen gas pressure on the plasma treatment was found to be the key parameter on the crystallization. This treatment works on amorphous films of various materials, independently of the film preparation method and substrate materials.

Akira Kinbara

Papers

Hardening Mechanism of Compositionally Modulated Ti-TiN Multilayer Films

AES and ELS measurements of TiN/Alumina ceramics

Adhesion measurement of thin films on glass substrates by scratch method

Studies of the Distribution of the Self-Bias Potential on an RF Electrode in Plasma

LP‐6: Late‐News Poster: Plasma Treatment for Room‐Temperature Crystallization of Amorphous Thin Films