Film characterization methods

The different growth modes discussed above have been exemplified also from structural studies. Froment and Lincot [247] used structural characterization methods, such as TEM and HRTEM, to determine the formation mechanisms and habits of chemically deposited CdS, ZnS, and CdSe thin film at the atomic level. These authors formulated reaction schemes for the different deposition mechanisms and considered that these should be distinguished to (a) atom-by-atom process, providing autoregulation in normal systems (b) aggregation of colloids (precipitation) ... 

Gas adsorption (physisorption) is one of the most frequently used characterization methods for micro- and mesoporous materials. It provides information on the pore volume, the specific surface area, the pore size distribution, and heat of adsorption of a given material. The basic principle of the methods is simple interaction of molecules in a gas phase (adsorptive) with the surface of a sohd phase (adsorbent). Owing to van der Waals (London) forces, a film of adsorbed molecules (adsorbate) forms on the surface of the solid upon incremental increase of the partial pressure of the gas. The amount of gas molecules that are adsorbed by the solid is detected. This allows the analysis of surface and pore properties. Knowing the space occupied by one adsorbed molecule, Ag, and the number of gas molecules in the adsorbed layer next to the surface of the solid, (monolayer capacity of a given mass of adsorbent) allows for the calculation of the specific surface area, As, of the solid by simply multiplying the number of the adsorbed molecules per weight unit of solid with the space required by one gas molecule ... 

We begin with the most routine characterization methods—electrochemical methods. We then discuss various instrumental methods of analysis. Such instrumental methods can be divided into two groups ex situ methods and in situ methods. In situ means that the film on the electrode surface can be analyzed while the film is emersed in an electrolyte solution and while electrochemical reactions are occurring on/in the film. Ex situ means that the film-coated electrode must be removed from the electrolyte solution before the analysis. This is because most ex situ methods are ultra-high-vacuum techniques. Examples include x-ray photoelectron spectroscopy [37], secondary-ion mass spectrometry [38,39], and scanning or transmission electron microscopies [40]. Because ex situ methods are now part of the classical electrochemical literature, we review only in situ methods here. 

Table 1 of a paper by Murr (2) lists problems and/or concerns related to specific interface materials and specific components of SECS. In Table 2 of the same work, he related topical study areas and/or research problems to S/S, S/L, S/G, L/L, and L/G interfaces. It is also useful to divide interface science into specific topical areas of study and consider how these will apply to interfaces in solar materials. These study areas are thin films grain, phase, and interfacial boundaries oxidation and corrosion adhesion semiconductors surface processes, chemisorption, and catalysis abrasion and erosion photon-assisted surface reactions and photoelectrochemistry and interface characterization methods. The actual or potential solar applications, research issues and/or concerns, and needs and opportunities are presented in the proceedings of a recent Workshop (4) and summarized in a recent review (3). 

As a probe of lattice vibrations, Raman spectroscopy is very sensitive to intrinsic crystal properties and extrinsic stimuli, especially in semiconductors. It may be employed to study crystal structure and quality, crystal orientation, optical interactions, chemical composition, phases, dopant concentration, surface and interface chemistry, and local temperatme or strain. As an optical technique, important sample information may be obtained rapidly and nondestructively with minimal sample preparation. Submicron lateral resolution is possible with the use of confo-cal lenses. These features have made it a vital tool for research labs studying semiconductor-based technologies. They also are increasingly important for the study of semiconductor NWs fabricated by both top-down and bottom-up approaches since many of the common characterization methods used with bulk crystals or thin films cannot be applied to NWs in a direct manner. 

Summary Silicone copolymers are hybrid matmals with varying phase separation levels. The polymers themselves as well as surfaces formed by these copolymers were analyzed by a variety of polymer and surface characterization methods. Atomic force microscopy was found to be especially suitable for analysis of thin polymer films. Both surface and bulk properties are dominated by the domain size and the silicone content. 

The combined information obtained by the different characterization methods applied allows the conclusion that deposits of ruthenium oxide at BDD, ranging from approximately one hundredth of a monolayer, maintain the physicochemical properties of RUO2, which proves the very limited degree of chemical interaction with the support. The deposits are most probably organized in nanoparticles growing around nucleation sites. When particles and clusters of particles reach a size of 50-60 nm, their charge-storage and catalytic behavior closely resembles that of thick oxide films. 

We will illustrate this quantitative characterization method of the microstructure with a study [BOU 03] conducted on a sample comprised of a lithium niobate film which is which is about 500 nm thick, deposited on a sapphire substrate cut parallel to the (0006) planes. This film was produced by laser ablation and is epitaxial so as to have the (0006) planes of LiNbOs parallel to the interface and the in-plane orientation is characterized by two variables. The epitaxy relations can be written ... 

We have utilized this wealth of background information in the design of our experiments. We use ultrafast laser techniques to drive sustained shocks into thin films of energetic materials, which are then interrogated using several different kinds of ultrafast spectroscopic and interferometric probes. The remainder of this chapter will describe these experiments in detail, especially the ultrafast laser shock production and characterization methods and the spectroscopic and interferometric anomalies caused by working with thin films, and present... 

As we described in Sect. 1, the application of electrochemical methods as a complementary technique to QCM is called EQCM. We discuss example applications of EQCM to film characterization in Sect. 3. 

Because the success of any of these systems depends on their ability to form hard, nearly impermeable, adherent films, the methods available to monitor and characterize this transition are important to the manufacture or application of coatings. One is dealing with high technology in the sense that the approaches used in colloid, solution, and polymer chemistry converge in the development of "compliance coatings."... 

Also of interest to electrochemistry is SIMS, which is another ex situ UHV method for surface and thin-film characterization (93, 103, 128, 129). This approach involves the bombardment of a surface with a high-energy primary ion beam (e.g., 15 keV Cs" ), which etches the surface by sputtering and produces secondary ions derived from the sur-... 

In the case of filmed powders, the results of particle size analysis depend veiy strongly on the characterization method. Each method measures a different particle property, fixim which sphere equivalent diameters are calculated. The underlying models assume homogeneous, spherical particles, which does not apply to the porous aggregates and agglomerates of these materials. 

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