Metal Island Films Research Articles

Giant Raman Scattering by Molecules at Metal-Island Films

Giant Raman Scattering by Molecules at Metal-Island Films

Effect of ionization of condensing flux and transverse electric field on nucleation of metal films on ionic crystals

Experimental data on the effect of ions in the flux of condensing metal on the orientation of island metal films on alkali halide crystals are given. The effect of ionization of the condensing flux and the transverse electric field is explained on the basis of a previously proposed model of nucleation and oriented growth on point defects on the crystalline substrate.

Optical behavior of a metal island film

Calculations for optical reflection, transmission, and attenuated-total-reflection of a two-dimensional distribution system of metal particles are carried out in two different ways; one is the usual way utilizing a fictitious plane-parallel film model and the other is the integration method of scattered waves. Both results are compared and discussed.

Electronic Processes in Metal Island Films

Electronic Processes in Metal Island Films

Elektronnye protsessy v metallicheskikh ostrovkovykh plenkakh

Elektronnye protsessy v metallicheskikh ostrovkovykh plenkakh

Anomalous optical absorption of aggregated silver films

A simple equation for the anisotropic dielectric constant of a metal island film is derived and applied to the ellipsometric measurement for an aggregated silver film. The experimental result can be explained when the inter-island dielectric constant is around unity. It is concluded that, in spite of the theoretical prediction that 2 F ∥+ F ⊥ = 1, the relation 2 F ∥+ F ⊥<1 holds for the observed values of the apparent depolarizing factors for electric fields parallel (F) and perpendicular ( F ⊥) to the substrate surface.

Reflection and transmission of light by a square non-polar lattice

The reflectance R and transmittance T of an infinite square lattice of polarizable nonpolar particles with retarded dipole-dipole interactions are rigorously calculated. The incident light has wavelength λ ⪢ lattice constant a and impinges upon the surface with an angle θ. First the amplitudes of the dipole moments of the particles are evaluated as functions of the electric field strength of the incident wave. Then the secondary fields emitted by all dipoles are summed and the reflected and transmitted waves are calculated. The general results for R and T as functions of θ, λ, a and the polarizability α of the particles obtained in the lattice model, are applied to the special case of a square lattice of metallic spheres of equal radius r ⪡ λ. The resulting formulae are compared with those found by Maxwell Garnett in a much more elementary, but very successful, approach for very thin films, consisting of a very large number of these metallic particles. The qualitative agreement between the expressions for R and T in both theories is consistent with recent optical experiments on very thin metallic island films which confirm the applicability of Maxwell Garnett's theory for calculations on the optical properties of these films.

Magnetoresistance and structure of sputtered metal island films on dielectrics

The transverse magnetoresistance and the structure of discontinuous gold and platinum films deposited by sputtering on various dielectric substrates have been investigated. It has been found that the qualitative changes of the magnetoresistance of such sputtered films, as a function of temperature and magnetic field, are mainly determined by the morphology of the films and do not depend on the nature of the metal. The factors determining the positive and negative magnetoresistance observed experimentally are discussed.

Transport Properties, Microstructure, and Conduction Model of Cosputtered Au–SiO2 Cermet Films

High-resistivity Au–SiO2 cermet films have been cosputtered. Their transport and structural properties have been examined and a model for electrical conduction is proposed. The electrical resistivity was found to be thermally activated, and the activation energy increased linearly as the metal content decreased. Activation energies varied from 0.01 to 0.07 eV. At a fixed temperature, the resistivity increased exponentially as the weight percent gold decreased. The cermets obeyed Ohm's law. No Hall effect was observed. Transmission electron micrographs showed very small (30–100 Å) discontinuous gold particles separated by very small SiO2 regions. Films were deposited at 20°, 500°, 520°, and 600°C. Gold particle size increased with increasing gold content or with increasing substrate temperature. Only polycrystalline gold was observed by electron diffraction. The typical infrared spectrum of SiO2 was recorded. 20°C cermets annealed at 600°C showed large particle growth and twinning. Electrical conduction in Au–SiO2 cermets is described by a model for conduction in island metal films. Good agreement is obtained between activation energies calculated from measured gold particle diameters and separations, and measured activation energies. From gold particle separations and estimated barrier height, calculations show that charge carriers tunnel through the SiO2. Many other models were considered, but none fit all the experimental relationships.