Film-substrate interface

Chemical Vapor Deposition. In chemical vapor deposition (CVD), often referred to as vapor transport, the desired constituent(s) to be deposited are ia the form of a compound existing as a vapor at an appropriate temperature. This vapor decomposes with or without a reducing or oxidizing agent at the substrate— vapor interface for film growth. CVD has been used successfully for preparing garnet and ortho ferrite films (24,25). Laser-assisted CVD is also practiced. 

Simulation of the RBS experimental spectra by means of the RUMP code has shown that, in both cases, the film composition was Fe203 (within 5%). The spectra also confirm the sharp character of the substrate/film interface, within the resolution... 

This expression is independent of the film thickness. Thus, when one considers reflective monitoring of metal film etching, only at the interface between film and substrate will a change in reflectivity be observed due to the change in refractive index. Although this is extremely useful for end point detection one still must apply films of known thickness for cases in which etch rate information is desired. 

The initial decrease in ionic film resistance and Increase in capacitance can be associated with either NaCl electrolyte or water entry into the film. From ER measurements this period is associated with a metal loss process at the substrate surface. However, between 9 to 23 days the ionic film resistance increases, which is associated with an arrest in metal loss at the substrate surface in ER measurements. It appears, therefore, that with the knowledge of an underfilm darkening phenomenon occurring at the substrate/coating interface, a film of a protective (ie passive or high ionic resistance) nature is produced during exposure. 

This occurs by an instability of one of the free interfaces the polymer-polymer interface, the film surface, or a combination of the two, each of which gives rise to a distinct lateral length scale. Which of the two capillary instabilities is selected is a complex issue. It depends on various parameters, such as polymer-polymer and polymer-solvent compatibility, solvent volatility, substrate properties, etc. in a way which is not understood. Despite this lack of knowledge, playing with these parameters permits the selection of one of the two distinct length scales associated with these two mechanisms, or a combination thereof. 

In chapter 7, all works discussed on model molecular systems for conjugated polymers refer to condensed molecular solid ultra-thin films, generally prepared by condensation of molecules from the effusion of a Knudsen-type cell, in UHV, on to clean metallic substrates held at low temperatures. Clean is defined as atomically clean as determined by core-electron level XPS, such that there is intimate contact between the molecules at the substrate-film interface, without the influence of, for example, a metallic oxide, hydrocarbon... 

In 1934, Langmuir s trainee, Blodgett [7], built the first trough for transferring the films from air water interface onto a solid substrate, and the first LB films were prepared. The transfer is represented schematically in Figure 12.3. First a Langmuir film is prepared on the air water interface. The film is compressed until it becomes solid, after which the pressure is maintained constant. Next a vertically oriented hydrophilic substrate is slowly immersed into water. The hydrophobic tails of the amphiphiles do not have a... 

Figure 3.9 Schematic illustration of the processes that can occur at a modified electrode, where P represents a reducible substance in a film on the electrode surface and A a species in solution. The processes shown are as follows (1) heterogeneous electron transfer to P to produce the reduced form Q (2) electron transfer from Q to another P in the film (electron diffusion or electron hopping in the film) (3) electron transfer from Q to A at the film/solution interface (4) penetration of A into the film (where it can also react with Q or at the substrate/film interface) (5) movement (mass transfer) of Q within the film (6) movement of A through a pinhole or channel in the film to the substrate, where it can be reduced. From A.J. Bard and L.R. Faulkner, Electrochemical Methods Fundamentals and Applications, 2nd Edition, Wiley, 2001. Reprinted by permission of John Wiley Sons, Inc...

Changes in SAW propagation velocity and attenuation are determined by the mechanical impedances at the substrate/film interface resulting from film translational and strain modes. The impedance associated with each film translation is jtaph, and with each strain mode is where Ef i are taken from Table... 

Next, we focus on a portion of the film that is small in lateral extent compared with the SAW wavelength. As the wave passes a fixed point, the lower surface of the film oscillates in response to the sinusoidal SAW surface displacement. If the film is acoustically thick (/7 1), the upper portions of the film tend to lag behind the driven substrate/film interface, inducing strains across the thickness of the film. This inertial deformation of the film results in nonuniform displacement across the film. 

Organic Collective effects of preparation method of conducting polymers, polymer morphology, properties of the substrate/film interface 24... 

The effect of slippage at a substrate-film interface can also be described in terms of sbp time [39]. To understand the physical meaning of the slip time, one can consider an adsorbate film on a substrate, moving at constant velocity. If the substrate stops, the velocity and momentum of the film decay exponentially, and the time constant of this process is the slip time. If this process is very rapid, i.e., we have a rigidly adsorbed film, the time constant will be close to zero, and there will be no noticeable shp. The shp time is related to the interfacial friction coefficient through the equation [39] ... 

In considering reflection by a surface bearing a film, the Drude equations, below, take into account the infinite number of reflections at substrate-film and film-ambient interfaces. Using the phase numbering of Fig. 4, the overall reflection coefficients for the assembly are designated by R... 

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