Chemical vapor deposition, modeling nucleation

Chemical vapor deposition (CVD) of thin solid films from gaseous reactants is reviewed. General process considerations such as film thickness, uniformity, and structure are discussed, along with chemical vapor deposition reactor systems. Fundamental issues related to nucleation, thermodynamics, gas-phase chemistry, and surface chemistry are reviewed. Transport phenomena in low-pressure and atmospheric-pressure chemical vapor deposition systems are described and compared with those in other chemically reacting systems. Finally, modeling approaches to the different types of chemical vapor deposition reactors are outlined and illustrated with examples. 

For a synthetic chemist the reaction rate is often the most crucial aspect of kinetics. Synthetic chemistry generally treats reactions in the gas or liquid phase where reactants have high mobilities and where distinct second phases are not normally formed. In semiconductor processing, reaction kinetics such as discussed above is essential to modeling techniques such as chemical vapor deposition (Chapter 12). Solid state chemistry and most materials science of solids is concerned with atomic transport as much as with reactant and product concentrations or thermodynamics. Furthermore, it is often the case that the forward reaction will not occur rapidly until some product is formed. This is normally referred to as a problem of nucleation and is similar to the classic conundrum, which came first, the chicken or the egg In the remainder of this section we will examine nucleation and then turn to diffusion transport kinetics in the following section. 

Chapter 10 deals with composite films synthesized by the physical vapor deposition method. These films consist of dielectric matrix containing metal or semiconductor (M/SC) nanoparticles. The film structure is considered and discussed in relation to the mechanism of their formation. Some models of nucleation and growth of M/SC nanoparticles in dielectric matrix are presented. The properties of films including dark and photo-induced conductivity, conductometric sensor properties, dielectric characteristics, and catalytic activity as well as their dependence on film structure are discussed. There is special focus on the physical and chemical effects caused by the interaction of M/SC nanoparticles with the environment and charge transfer between nanoparticles in the matrix. 

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