Growth Of Ag Films Research Articles

Optical constants of silver films on fluoride films and their aging histories

ATR measurements of optical constants of Ag films on fluoride films have been carried out in situ during growth of Ag films. In the case of CaF 2 films, for example, it has been found that coalescence of Ag islands starts at thicker optical thickness as the increase of thickness of CaF 2 films. Moreover, aging histories of Ag films on CaF 2 and MgF 2 films have been observed.

Nuleation and Growth of Thin Ag Films Vacuum‐deposited onto W

AbstractAn attempt to analyse the nucleation and growth phenomenon in a typical “Stranski‐Krastanov” (SK) growth system ‐ Ag/W (PAUNOV, MICHAILOV 1979; MICHAILOV), in terms of island growth theory was made. Ag‐layers were analysed by the use of scanning electron‐and optical microscopes. A strong dependence of the nucleation kinetics on supersaturation and grain orientation was found to exist. On the basis of known rate equations, the number of atoms in the critical cluster i and the value of nucleation potential barrier E were estimated. The comparison between the experimentally obtained size‐, first nearest neighbour‐ and radial distributions and theory shows that: 1) nucleation and growth processes proceed through a surface diffusion of the atoms; 2) no coalescence between the crystallites and no crystal mobility exist.

Ag thin film growth on hydrogen-terminated Si(100) surface studied by TOF-ICISS

Using time-of-flight (TOF) type low-energy impact-collision ion scattering spectroscopy (ICISS) and elastic recoil detection analysis (ERDA), we have investigated (1) the effect of the saturation of surface dangling bonds of Si(100) surfaces with atomic hydrogen upon Ag thin film growth, and (2) the effect of hydrogen adsorption onto Ag thin films (∼ 1 ML coverage) on the clean surfaces. We find that (1) epitaxial growth of Ag films is promoted by the hydrogen atoms residing at the film/substrate interface and (2) adsorption of hydrogen onto Ag monolayer deposited on Si(100) surfaces transforms the Ag monolayer into very small crystallites of Ag(100) grown epitaxially on the Si(100) substrate.

Hydrogen-mediated epitaxy of Ag on Si(111) as studied by low-energy ion scattering.

We have investigated the effect of the saturation of surface dangling bonds of Si(111) surfaces with atomic hydrogen upon Ag thin-film growth. By using time-of-flight-type low-energy ion scattering-recoil analysis techniques, we find that the growth mode of Ag thin films is drastically changed by the hydrogen termination of Si(111)-7\ifmmode\times\else\texttimes\fi{}7 surfaces and that the epitaxial growth of A-type Ag(111) films is promoted by the hydrogen atoms residing at the film/substrate interface.

The growth of Ag films on Ni(100)

Using scanning tunneling microscopy, low-energy electron diffraction (LEED), and Auger electron spectroscopy we have studied the growth of Ag films with coverages between 1/6 and 1.45 monolayers on room temperature Ni(100) substrates. In the submonolayer coverage range we observe a condensation of the Ag deposit in form of a network of connected islands of monoatomic height preferentially at step edges of the substrate. Two domains are identified on the Ag islands by the presence of orthogonal line structures. They are interpreted in terms of the c(2×8) LEED pattern. The Ag islands coalesce for a coverage of less than one monolayer. The second atomic Ag layer shows a different growth structure indicating a more perfect arrangement of Ag atoms in a face-centered-cubic (fcc) (111) layer.

Hydrogen-termination effects on the growth of Ag thin films on Si(111) surfaces

Using elastic recoil detection analysis (ERDA) and low energy electron diffraction (LEED), we have studied the hydrogen termination effects on the growth of Ag thin films on Si(111) surfaces. We have found for the first time that adsorbed hydrogen of about 1.5 monolayer strongly affects the initial growth process of Ag thin films and promotes the formation of parallel-oriented Ag(111) crystallites, Ag(111) [11 2]∥Si(111)[11 2] . Absolute coverage of hydrogen measured by ERDA has shown a rather large reduction during the Ag film growth, indicative of the occurrence of the atomic replacement of Ag and hydrogen.

The structure and morphology of Ag film growth on Cu(110)

Low-energy electron diffraction (LEED), Auger electron spectrometry (AES), and workfunction change measurements have been used to characterize the structure and morphology of ultrathin Ag films grown on Cu(110). The LEED data show pronounced differences in diffraction arrays for multilayer deposition at 120 and ⩾ 300 K that are, respectively, consistent with disordered layering and layer-cluster growth morphologies deduced from AES. Following the initial growth of Ag in-registry with the substrate troughs, a split c(2 × 4) monolayer structure is observed that to first order is interpreted in terms of a distorted Ag(111) overlayer with a seventh-order superlattice periodicity normal to the substrate troughs. At 120 K, postmonolayer deposition reconstructs the monolayer template, producing a p(8 × 1) → p(8 × 3) → p( 8 7 × 3 ) sequence of diffraction features. These data are consistent with development of a heavily corrugated and strained Ag(110) film that grows from a configuration where the first atomic layer of Ag is captured in the Cu troughs. Multilayer coverages at ⩾ 300 K give LEED features that are indicative of clusters, which gradually coalesce to produce {111} microfacets in a geometry that is consistent with the 120 K structural observations. In agreement with trends seen in bulk binary properties of Ag and Cu, the film development appears to be driven by dominant Ag-Ag bonding as modulated by the row-trough substrate corrugation. The clustering is viewed as the most energetically favorable way to relieve the interfacial strain and attain a bulk Ag film in the absence of low-temperature kinetic limitations.

The structure and morphology of Ag film growth on Cu(110)

The structure and morphology of Ag film growth on Cu(110)

7402. Growth of ultrathin Au and Ag films on a modified Ru surface: H Blud et al, Vacuum, 41, 1990, 1106–1108

7402. Growth of ultrathin Au and Ag films on a modified Ru surface: H Blud et al, Vacuum, 41, 1990, 1106–1108

Adsorption‐Desorption Transient Measurements of the Initial Stages of Growth of Thin Ag Films on W

AbstractOn the basis of precise analysis of series adsorption‐desorption transients (ADT) – registered mass‐spectrometrically (MS) around the transition points from adsorption equilibrium to real film growth, the critical parameters of phase formation process for Ag on W – coverage, impingement rate and supersaturation were estimated. It was established that the film growth starts at coverages ∼ (2.05 – 2.15) × 1015 cm−2 at hardly appreciable supersaturations, following the “Stranski‐Krastanov” (SK) growth mode – through the formation of three‐dimensional (3D) clusters on the top of complete second Ag layer.

ＲＨＥＥＤ法によるＢｉ‐Ｓｒ‐Ｃａ‐Ｃｕ‐Ｏ超伝導単結晶上でのＡｇ薄膜のエピタキシャル成長観察

ＲＨＥＥＤ法によるＢｉ‐Ｓｒ‐Ｃａ‐Ｃｕ‐Ｏ超伝導単結晶上でのＡｇ薄膜のエピタキシャル成長観察

The growth of Ag films on Si(100)

Room temperature condensation of Ag films on Si(100) in the submonolayer and monolayer range has been studied by means of voltage-dependent scanning tunneling microscopy and in some cases by scanning tunneling spectroscopy (STM). The uncovered Si(100) substrate showed various kinds of local atomic structures, which influence the growth behavior of the Ag films. Short heating of Si(100) produced a 2×1 reconstruction with a comparably small number of defects. Extensive heating increased the number of defects and finally led to ordering of defects and formation of a 2×8 reconstruction showing weak 1/8 and strong 1/2 order low-energy electron diffraction (LEED) beams. In the submonolayer range Ag condenses in row-like structures along the dimer rows of the substrate (i.e., vertical to the dimer direction). The Ag atoms are repelled from the Si defect sites. For a large number of defects (e.g., for a 2×8 reconstructed substrate) 1 ML Ag does not cover completely the substrate surface but already starts with the growth of three-dimensional Ag islands. The Stranski–Krastanov growth mode of the system Ag/Si (100) (interface+island formation) has therefore been convincingly established. The interaction between the Ag atoms in the interface layer and the Si substrate is remarkably weak. We reproducibly observed current instabilities near Ag sites and distinct diffusion processes of the Ag atoms during the STM measurements.

Growth of ultrathin Au and Ag films on a modified Ru surface

Using TDS, LEED and AES we have studied the adsorption of Ag and Au on an oxygen precovered Ru(001) surface in comparison with the growth mechanisms of these adsorbates on the non-modified substrate. Oxygen desorbs from Ru at higher temperatures than Ag and causes even the smallest detectable Ag coverage to sublimate like bulk silver (in contrast to the layer-by-layer growth on pure Ru). In turn, the TD-spectrum of Au is hardly affected because oxygen desorbs partially before gold. However, a quantitative analysis of AES intensities, taken at room temperature, as well as simple model calculations support a 3D island growth mode of Au on the oxygen precovered Ru surface as well.

LEELS study of the formation of the AG-semiconductor (Si. Ge.A 3B 5) interface at 10K

The LEELS spectra of Si, Ge and A 3B 5 compounds were taken at RT and LT during Ag deposition in the coverage range 0–18 ML. Annealing fron LT to RT was studied as well. Strong chemical interaction between Ag and Ge already at LT was observed in distinction from the system Si+Ag where it starts only at higher temperatures. GaAs+Ag, InP+Ag and InAs+Ag systems behave qualitatively identical. InSb+Ag strongly differs from other systems concerning silver plasmon behaviour. We suppose that it is due to BCC silver formation at LT. Our data argue in favor of the following mechanisms of Ag film growth at RT : Stranskii-Krastanov for Si and Ge substrates and Volmer-Weber for GaAs, InAs and InP.

Processes of atom mixing at the boundary in Ag-Cu and Ag-Mo systems under argon ion bombardment

Analysis of some aspects for dynamic ion mixing at the film-substrate boundary in Ag-Cu and Ag-Mo systems under argon ion bombardment during Ag film growth has been carried out. Evaluations of vacancy concentration formed in unit time under ion beam action show that without taking into account recombination and annealing the low energy ions are capable of creating a defect concentration in the film-substrate interface 1-2 orders of magnitude smaller than high energy ions. In this case the concentration is comparable with the thermo-dynamical equilibrium concentration at temperatures close to the Ag melting temperature. Proceeding from the comparison of diffusion activation energies, vacancy migration rates as well as taking into consideration mechanical characteristics of material, a conclusion has been drawn about mutual penetration and preferential penetration of substrate material into Ag coating as the result of radiation enhanced processes. Experimental results have confirmed these estimations revealing the considerably larger Ag films adhesion to Mo substrate than to Cu under the same conditions of film formation. The friction tests have shown that wear of Ag-Cu and Ag-Mo solid solutions produced under Ar ion bombardment of the growing Ag film is much lower than the wear of Ag film without ion irradiation.

Growth and electronic structure of ultra-thin Pd and Ag films on Al(111)

Pd and Ag films vapor-deposited onto Al(111) were studied by AES, LEED and angle-resolved UPS. Both metals grow in the Stranski-Krastanov mode. With the substrate at 520 K Ag grows epitaxially. For Pd no ordered structures were found in the monolayer region. For Ag mainly two bands were found for the 4d states showing a maximum dispersion of 0.4 eV and a splitting into three bands in the outer parts of the two-dimensional Brillouin zone. In the monolayer the Pd4d emission lies 4 eV below the Fermi edge, which means that it maintains its atomic 4d 105s 0 configuration.

Growth and electronic structure of ultra-thin Pd and Ag films on Al(111)

Abstract Pd and Ag films vapor-deposited onto Al(111) were studied by AES, LEED and angle-resolved UPS. Both metals grow in the Stranski-Krastanov mode. With the substrate at 520 K Ag grows epitaxially. For Pd no ordered structures were found in the monolayer region. For Ag mainly two bands were found for the 4d states showing a maximum dispersion of 0.4 eV and a splitting into three bands in the outer parts of the two-dimensional Brillouin zone. In the monolayer the Pd4d emission lies 4 eV below the Fermi edge, which means that it maintains its atomic 4d 10 5s 0 configuration.

Adsorbed xenon atoms as local surface structure probes: The initial growth of thin Ag films on Ru(001)

Photoemission of Adsorbed Xenon (PAX) is shown to provide valuable information on the initial growth mode of a thin, 0.2 monolayer silver film on Ru(001) at 50 K on an atomic scale. By taking advantage of the fact that the Xe(5p 3 2 , 1 2 ) UPS spectra of adsorbed xenon allow a clear distinction between Xe atoms being adsorbed on Ag sites, on Ru sites, and at mixed Ag-Ru sites, a model is proposed, according to which the amount of 0.2 ML silver is distributed on the Ru(001) in the form of small islands without alloying. From the 5p UPS intensities of the various Xe adsorption states the radius as well as the number of these islands (assumed to be circular) could be calculated. The number of these islands agrees remarkably well with the number of defects on the original Ru(001) substrate, which was again “titrated” by means of xenon adsorption. These defects are therefore regarded as nucleation centers for the incipient Ag island formation. This model is supported by accompanying AES, LEED, Xe desorption and work function measurements.

Adsorbed xenon atoms as local surface structure probes: The initial growth of thin Ag films on Ru(001)

Adsorbed xenon atoms as local surface structure probes: The initial growth of thin Ag films on Ru(001)

A LEED-AES study of the growth of Ag films on Si(100)

A LEED-AES study of the growth of Ag films on Si(100)