A new compilation, based on a literature search for the period 1969–1976, is made of experimental data on the work function. For these 44 elements, preferred values are selected on the basis of valid experimental conditions. Older values, which are widely accepted, are given for 19 other elements on which there is no recent literature, and are so identified. In the data for the 63 elements, trends that occur simultaneously in both the columns and the rows of the periodic table are shown to be useful in predicting correct values and also for identifying questionable data. Several illustrative examples are given, including verifications of predictions published in 1950.

The work function of the elements and its periodicity

The mechanical properties of thin films on substrates are described and studied. It is shown that very large stresses may be present in the thin films that comprise integrated circuits and magnetic disks and that these stresses can cause deformation and fracture to occur. It is argued that the approaches that have proven useful in the study of bulk structural materials can be used to understand the mechanical behavior of thin film materials. Understanding the mechanical properties of thin films on substrates requires an understanding of the stresses in thin film structures as well as a knowledge of the mechanisms by which thin films deform. The fundamentals of these processes are reviewed. For a crystalline film on a nondeformable substrate, a key problem involves the movement of dislocations in the film. An analysis of this problem provides insight into both the formation of misfit dislocations in epitaxial thin films and the high strengths of thin metal films on substrates. It is demonstrated that the kinetics of dislocation motion at high temperatures are expecially important to the understanding of the formation of misfit dislocations in heteroepitaxial structures. The experimental study of mechanical properties of thin films requires the development and use of nontraditional mechanical testing techniques. Some of the techniques that have been developed recently are described. The measurement of substrate curvature by laser scanning is shown to be an effective way of measuring the biaxial stresses in thin films and studying the biaxial deformation properties at elevated temperatures. Submicron indentation testing techniques, which make use of the Nanoindenter, are also reviewed. The mechanical properties that can be studied using this instrument are described, including hardness, elastic modulus, and time-dependent deformation properties. Finally, a new testing technique involving the deflection of microbeam samples of thin film materials made by integrated circuit manufacturing methods is described. It is shown that both elastic and plastic properties of thin film materials can be measured using this technique.

Mechanical properties of thin films

Atomic-scale control and manipulation of the microstructure of polycrystalline thin films during kinetically limited low-temperature deposition, crucial for a broad range of industrial applications, has been a leading goal of materials science during the past decades. Here, we review the present understanding of film growth processes—nucleation, coalescence, competitive grain growth, and recrystallization—and their role in microstructural evolution as a function of deposition variables including temperature, the presence of reactive species, and the use of low-energy ion irradiation during growth.

Microstructural evolution during film growth

Ultrathin metal films and particles on oxide surfaces: structural, electronic and chemisorptive properties

Surface studies of supported model catalysts

Nanocomposite thin film coatings of MoS2-added CrN/TiAlN tribological multilayers were prepared by reactive co-sputtering of Ti/Al 50/50 at.%, pure chromium and MoS2 targets of the independently d.c. driven unbalanced magnetrons. Nano-scaled tri-layer system with periodic thickness in a range of 4-10 nm of CrN, TiAlN and MoS2 compound layer with a broad interface, in which the composition is continuously varying, was developed. The 4-5 µm thick coatings were deposited on high-speed steel substrates for tribological measurements. Structure characterization of the as-deposited coatings was performed by cross sectional transmission electron microscopy (XTEM) analysis. The crystallinity of the CrN and TiAlN sub-layers in the nano-scale multilayered system decreases with increasing thickness of the MoS2 sub-layer. It has been found that the structural properties and hardness of the films were correlated with the multiple-target design and MoS2 nanolayer thickness.

FULLEREN-LIKE STRUCTURE OF NANOCRYSTALLINE MoS2 TRIBOLOGICAL COATINGS PREPARED WITH COMPOSITION- MODULATED INTERFACES

Coevaporated amorphous Ge1−x
 Mo
 x
 films (0.07≤x≤0.32) were investigated by means of electron microscopy electron and X-ray diffraction and electrical measurements. Inhomogeneity in the Mo concentration has been found only in the samples of high metal content. Mo causes drastic changes in the ED and XRD patterns of a-Ge. The experimental interference functions forx≤0.22 are well matched by those calculated on the basis of a structural model for a relaxed a-Ge random network in which the Mo atoms fill part of the empty space. In the range 80–470 K both samples withx=0.07 and 0.16 display activation energies ΔE 6 times less than those of a-Ge and close tok
 BT, which is indicative of hopping on high density localized states. Below 80 K for the samples of high Mo content ΔE becomes very small suggesting the presence of metallic regions, which dominate conduction at lowT.

Structure and electrical properties of amorphous Ge-Mo films

Abstract In the present work the influence of the level of oxygen doping on the structure of TiN films was investigated by dedicated experiments. The films were deposited at 400°C in an all metal UHV device by unbalanced magnetron sputtering at the same Ar and nitrogen flow rates, but the oxygen flow rate was changed in the experiments, incorporating oxygen in the range of 4 and 20 at.%. The structure of the films was investigated by XRD, Auger electron (AES) and X-ray photon electron (XPS) spectroscopy and transmission electron microscopy (TEM). The results discovered the crystal face anisotropy in the incorporation-segregation of oxygen leading to the change of the <111> texture to <002>. The structure analysis revealed that the <002> texture is developing also by competitive growth of crystals, which is the result of the limitation of the growth of the <111> oriented crystals by the TiO2 layer developing on their growth surface by the segregated oxygen species. The oxygen incorporating in the crystal lattice on the 002 crystal faces of the <002> oriented crystals is segregated by surface spinodal decomposition, developing nm sized 3D TiO-2 inclusion both in the bulk of the columns and the column boundaries.

/pdf/effect-of-oxygen-doping-on-the-structure-of-tin-surface-4qm3sl20i0.pdf

Effect of Oxygen Doping on the Structure of TiN Surface Coatings

Epitaxial growth of Ni films deposited on MgO(001) by DC sputtering at 2.5keV in pure Ar gas is studied as functions of negative bias voltage V s and substrate temperature T s . V s ranges from 0 to -110V and T s from 190 to 280°C. The crystalline structure of the film is examined by RHEED, X-ray diffraction(XD) and X-TEM. At T s =280°C, the effect of V s in inducing the epitaxial growth of the film is very pronounced, i.e., the epitaxial film with Ni(001) II MgO(001) and Ni II MgO is obtained for -V s ≧80V. No epitaxial growth of the Ni film is observed at T s s .

Epitaxial growth condition of ni films dc-bias-sputter-deposited on mgo(001)

Cu-Ag films were deposited in vacuum of 10−5−10−6 mbar onto freshly cleaned Si wafers. The composition of the films corresponded to Cu, Cu9Ag1, Cu4Ag6 and Ag. The films were investigated by X-ray diffraction and pole figures of and directions were recorded. TEM and XTEM were used to determine the morphological properties of the films. We found that Ag modifies the interaction of Cu with the Si substrate. Low amounts of Ag are enhancing the formation of the biaxial texture of Cu. Larger amounts of Ag result in the formation of wire texture of both Ag and Cu components.

https://iopscience.iop.org/article/10.1088/1742-6596/100/8/082008/pdf

Péter B. Barna

Papers

FULLEREN-LIKE STRUCTURE OF NANOCRYSTALLINE MoS2 TRIBOLOGICAL COATINGS PREPARED WITH COMPOSITION- MODULATED INTERFACES

Structure and electrical properties of amorphous Ge-Mo films

Effect of Oxygen Doping on the Structure of TiN Surface Coatings

Epitaxial growth condition of ni films dc-bias-sputter-deposited on mgo(001)

Development of texture and morphology in Cu-Ag thin nanocomposite films on Si