Single-crystal Silver Films Research Articles

Submonolayer and single crystal film from ligand-stabilized silver nanoparticles

Ligand-stabilized silver nanoparticles were synthesized by a method of ultraviolet light irradiation reduction from a parent solution containing inorganic silver salt, then deposited on carbon coated copper microscope grid by electrophoretic technique. All samples were examined on transmission electron microscope. The results indicate that when the parent solution was irradiated for 5 min a submonolayer of silver nanoparticles was obtained; however, when the parent solution was irradiated for 10 min single crystal silver films were formed. The mechanisms about formation of the submonolayer of nanoparticles and the single crystal silver films were discussed.

Epitaxial growth of thin silver films on water- treated NaCl surfaces

Treatment of air-cleaved NaCl substrates with distilled water prior to vacuum deposition of the metal has been found to promote the epitaxial growth of continuous thin silver films (30 nm or less) at low temperatures. Well-developed (100) single-crystal silver films have been grown at a substrate temperature as low as 100°C, while randomly oriented polycrystalline films developed at 50°C or below. Changes in nucleation density of silver and cleavage step structure on NaCl due to water treatment were observed by surface decoration methods and are tentatively explained.

A device for performing surface-plasmon-polariton-assisted Raman scattering from adsorbates on single-crystal silver surfaces

We describe the theory, design, and performance of a new surface-plasmon-polariton-(SPP) assisted Raman scattering instrument that exploits the Kretschmann geometry. In contrast to previous methods, our device allows the entire SPP emission cone to be collected, thus optimizing the detected Raman intensity. This advantage makes surface Raman scattering from adsorbates on relatively smooth or single-crystal silver films possible with routine optics and electronics in the rest of the system. We demonstrate the concept with data acquired from a monolayer of paranitrosodimethylanaline (pNDMA) on nearly smooth polycrystalline Ag and single-crystal Ag(111) with air or liquid as the ambient medium.

Quantitative Analysis of the Intensity of Interference Fringes of X-Ray Diffraction Line Profiles

X-Ray diffraction spectra of thin films may show characteristic interference fringe patterns which wash out with increasing surface roughness. From the intensity of the secondary maxima quantitative data on the roughness can be derived. Model calculations are presented assuming that the distribution of heights about the mean surface level is Gaussian. The theory is applied to explain the diffraction spectra of single-crystal silver films. It is shown that some uncertainty in the results remains due to the influence of lattice distortions

Evaporation of rhodium films onto single-crystal silver films and mica cleavages

Evaporation of rhodium films onto single-crystal silver films and mica cleavages

Determination of twinning stresses in (100) silver films

(100) single-crystal silver films, of thickness 90 nm, were prepared by vapour deposition and mounted on copper grids. The films were indented by projecting spherical particles at them and by loading them with a stylus. Twins and long dislocations lying in the plane of the foils were observed in the deformed specimens. It is shown that twinning is the dominant mode of deformation and accounts for the great majority of the deformation energy given to the films. The area of twinned material projected on the film plane was measured by transmission electron microscopy. The energy needed to produce an identation can be estimated for both impact and quasi-static loading. The measurements made enable twinning stresses to be calculated.

Effect of thickness on the plastic deformation of (100) silver films

Abstract (100) single-crystal silver films with thicknesses 90 nm and 250 nm were prepared by vapour deposition. Examination by transmission electron microscopy showed that the 90 nm films contained numerous growth twins, but no evidence of these was found in the 250 nm films. The films were plastically deformed, both as-deposited and after annealing. by mounting them on grids and indenting them with a fine-tipped stylus. It was found that the 90 nm films deformed by twinning, but that the 250 nm films did not. It is suggested that this is because growth twins are necessary as nuclei for the formation of deformation twins. Annealing did not affect the basic modes of deformation of the films; however, in the case of 90 nm films a given applied load produced indentations of greater depth in annealed films. It is believed that this is because the point-defect density in the specimens is reduced by annealing, thus allowing twinning dislocations to propagate more easily.

Resistivity study of single-crystal silver films from 4.2 to 56°K

An analysis of the results of electrical resistivity measurements from 4.2 to 56 °K for single-crystal Ag films shows the nature of the temperature variation as predicted by the theory of Azbel and Gurzhi based on the Olsen effect.

Thin film strength properties by indentation techniques

Abstract Using indentation techniques the micro-deformation of freely suspended, thin, evaporated films has been studied in slow loading and impact situations. The films were mounted on electron microscope grids and loads were applied in the unsupported regions between the grid bars. For the slow loading studies, measured loads were applied with the tip of a tungsten stylus, and impact was achieved by projecting small spherical particles against the specimens. Polycrystal and single-crystal silver films were studied; indentation shape and size effects were recorded for deformation under controlled loading conditions. It is suggested that the indentation method could be useful for rapidly comparing the strength properties of thin films.

The preparation and characterization of single crystal silver films

Single crystal films ≈0.5 μm thick with dislocations densities ≈10 −7 lines/cm 2 have been prepared by vacuum evaporation and epitaxial growth on cleavage surfaces of NaCl. The key step in the process is the on-substrate annealing at an intermediate film thickness (≈0.15 μm). These low dislocation density films have given X-ray rocking curves of less than 1.5' fwhm. Differences in rocking curve widths for Laue and Bragg geometry are consistent with the thickness effect expected from X-ray diffraction theory.

Dislocation structure in thick single-crystal silver films subjected to the lüders deformation

The plastic behavior and the deformed structure of (102̄) single-crystal silver films with thickness of 1.0 μ and dislocation density of1 × 108 cm −2 have been studied with tensile test and high voltage electron microscopy. Under the single-glide condition with the tensile axis [231], the plastic deformation proceeds with the spread of Lüders band. In the Lüders band, sharp slip line markings running across the entire specimen surface are produced by the operation of the primary slip system. Cross slip bands were never observed. A large amount of slips concentrates in plastic zones with thickness of about 0.3μ forming the surface slip marking. In the Lüders band, positive and negative plastic zones, in which the positive and negative edge dislocation groups exist respectively, are alternately arranged with the separation of about 3μ, and the lattice is bent at the place of the plastic zone. This dislocation model coincides with the model presented by Mori et al. Based upon this model, secondary dislocations observed in transmission electron micrographs are discussed.

Geometrical Size Effect in Resistivity and Hall Coefficient in Single-Crystal Silver Films

Geometrical Size Effect in Resistivity and Hall Coefficient in Single-Crystal Silver Films

Structure and Tensile Properties of Thick Single-Crystal Silver Films Formed by Vacuum Deposition

Single-crystal silver films of various surface orientations were prepared with thicknesses of 0.4–7 μ, and tensile tests were carried out for the films in as-deposited and annealed (860° C) states. Stress-strain curves were found to depend on the tensile direction and the film orientation. Structural observations were done with 500-kV and 1-MV electron microscopes. Dislocations are tangled in the as-deposited films thicker than 0.2 μ. Dislocation density is in the order of 1010/ cm2. Twins and stacking faults do not exist. The annealing causes subgrain formation in (11̄0) and (111) films, but recrystallization in (001) films. Deformed structures are different according to the tensile directions. Based on the structural observations, the mechanical properties are discussed.

SIZE EFFECT IN THIN SINGLE-CRYSTAL SILVER FILMS

A discrepancy has been observed between the experimental behavior of electrical resistivity and temperature coefficient of resistivity as a function of film thickness in thin single-crystal silver films when compared with geometrical size effect theory. The discrepancy has been attributed to the observed change in the microstructure of the films as shown by the transmission electron microscopy study and to the effect of lattice as well as electron energy quantization on electrical conduction. The study calls for an exact calculation of the role of quantization in structurally perfect thin films.

Surface Structure of Clean Au (100) and Ag (100) Surfaces

The proposal that reconstructed phases may exist for the clean (100) surfaces of some fcc metals is considered in terms of results obtained from low-energy electron-diffraction studies of epitaxial single-crystal films of silver and gold grown in ultrahigh vacuum (1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}10}$ Torr). The purpose of this paper is to show that the experimentally observed (1\ifmmode\times\else\texttimes\fi{}5) structure on the Au(100) surface and the (1\ifmmode\times\else\texttimes\fi{}1) structure on the Ag (100) surface are characteristic of the clean surface, and to suggest a possible atomic structure for the reconstructed Au(100) surface. The evidence from the epitaxial film studies indicates the occurrence of a thin hexagonal layer of pure gold on the (100) substrate rather than an impurity-stabilized surface layer of hexagonal symmetry, of some unknown substance. It is suggested that the interfacial energy between a thin hexagonal layer and the nonreconstructed substrate may be the determining factor in the occurrence of reconstruction on the (100) surface of fcc metals.

LOW-ENERGY ELECTRON DIFFRACTION STUDIES OF EPITAXIAL GROWTH OF SILVER AND GOLD IN ULTRAHIGH VACUUM

The occurrence of epitaxial growth of single-crystal films of silver and gold has been found to depend critically on exposure of the substrate surface to an electron beam prior to deposition. Single-crystal films with a (100)∥(100), (100)∥(100) orientation were produced on irradiation surfaces at low supersaturation levels in the absence of contaminating gases. It is proposed that the controlled production of point defects on the clean surface play a critical role in the nucleation and growth required for epitaxy.

The growth of single crystal films of silver on rocksalt by sputtering

Thin films of silver on rocksalt have been prepared by diode sputtering in an argon discharge. Deposition rate, substrate temperature, and film thickness have been varied, and dependence of orientation on these parameters has been studied. Within a deposition rate range of 0.1 to 1.15A/sec, films have been grown with (100) [110]Ag / / (100) [110]NaCl orientation, at temperatures in the range −35 to 0° C. Higher rates required higher temperatures. Films giving these results were all 200 A in thickness. A thickness dependence of orientation has been observed for films below 120 A in thickness.

425. Orientation and thickness dependence of stress-strain curves in vacuum-deposited single crystal silver films: M Fukamachiet al, Acta Metallurgica, 14(1), Jan 1966, 62–63, (from Japan)

425. Orientation and thickness dependence of stress-strain curves in vacuum-deposited single crystal silver films: M Fukamachiet al, Acta Metallurgica, 14(1), Jan 1966, 62–63, (from Japan)

Orientation and thickness dependence of stress-strain curves in vacuum deposited single crystal silver films

Orientation and thickness dependence of stress-strain curves in vacuum deposited single crystal silver films

Direct observation of defects in evaporated silver

Abstract Single-crystal films of silver were made by evaporation of silver onto the cleavage surface of a heated rock-salt crystal. The crystalline defects present in the detached films were studied by transmission electron microscopy. In fresh areas of the foil, numerous simple stacking faults confined to a single plane were observed. The number varied between 5 × 109 and 1 × 1010 cm−2. There was a strong tendency for the partial dislocations to lie in 〈110〉 directions. The morphology of the simple fault shapes resulting is considered in detail. Electron beam stressing resulted in the dissociation of whole dislocations and in the widening of faults already present. The interaction of the faults to form complex faults on several planes, and the effects of holes and dislocations were studied. Some areas showed minor defects consisting of dislocation loops and tetrahedral stacking faults. Preliminary annealing experiments indicate that the simple faults are remarkably stable at 300°c. The origin of the various defects is discussed. It is concluded that most simple faults probably form by dissociation of dislocations which may (1) grow in from the substrate, (2) nucleate at silver patch edges during growth, (3) form by impingement of patches on a {110} plane during growth.