Epitactical growth

The X = 1 PB is particularly important since it is often associated with epitactic growth. 

Crystal structure. A close match in the lattice parameters of the film and substrate is one important requirement for epitactic growth. There must also be a reasonable number of coincident lattice sites on either side of the interface. Frequently, although not always, this means that the film and substrate should have similar crystal structures. The higher the number of coincident sites, the better the chance of good epitaxy. 

A different approach towards the incorporation of metal oxide clusters into zeo-litic pores via chemical vapor deposition has been studied extensively by Ozin et al. [236 - 240]. They developed a method denoted as intrazeolite metal carbonyl phototopotaxy . Metal carbonyls are used as precursors to obtain the occluded guest component because of their volatility, fitting molecular dimensions, ease of purification, ready availability, and facile and quantitative conversion to the respective metal oxide materials with minimal contamination by carbon [236, 240]. The metal carbonyl precursors are transformed into the metal oxides by photochemical oxidation. The term phototopotaxy is meant to indicate the similarity of this preparation method to epitactical growth of semiconducting oxide layers on planar surfaces commonly used to form low-dimensional quantum nanostructures for applications in electronic and optical devices [238]. 

We defined epitaxy in Chapter 15. Incidentally, the grammatically correct adjective from epitaxy is epitactic or better still epitaxic, but epitaxial has come to be accepted even by the Oxford English Dictionary because it is now so widely used. In many of the deposition techniques, it is not clear where the hyphen(s) should be (if there should be one) but thin-film growth is always the way to grow thin films and adverbs are never hyphenated to parts of verbs. 

The interaction of the laser beam and the target produces a plasma consisting of species having high kinetic energy, which enables epitactic film growth at low substrate temperatures. 

Thin films of ceramic materials are important both scientifically and commercially. For example, the operation of semiconductor devices relies on thin dielectric layers. In this chapter we described some of the main techniques used to produce such films. The conunon feature of all techniques for growing thin films is that we require a vacuum chamber. Deposition may occur at atmospheric pressure (e.g., some versions of CVD), but prior to deposition the chamber was evacuated. The choice of technique is based on several factors, including the type of material being deposited, whether we need an epitactic layer, and often the cost. The substrate plays an important role in the growth of thin films and thus we need to know the properties of the substrate and how to prepare it. Some of the techniques we described, such as PECVD, are important not only for growing thin films but also for producing nanostructures such as nanowires and nanosprings. 

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