Homoepitaxial deposition

In this section we are concerned with epitaxial deposition. The word Greek taxis can mean an arrangement or a positioning. The Greek preposition epi in this context means upon. Epitaxial, then, means that the deposited layers are arranged on something namely, the substrate or layers already deposited. The particular arrangement is crystalline. The term epitaxial deposition is reserved for crystalline deposition. Epitaxial is further refined to include homoepitaxial and heteroepitaxial. In homoepitaxial deposition, the deposited material is the same as the substrate silicon on silicon and diamond on diamond are examples of homoepitaxial deposition. In heteroepitaxial deposition the deposited material is different from the substrate diamond on silicon or GaN on sapphire. 

An in-situ STM study has been initiated to investigate the various processes associated with electrodeposition of Cu-(Ni, Co, Fe) multilayers. This paper gives an example of the remarkable utility of STM for imaging the structure and dynamics associated with electrodeposition processes. Specifically, the significant role of anion adsorption in homoepitaxial deposition on Cu(100) has been demonstrated. 

Once again, polarised microscopy appears to be the best all-round technique because of its high resolution coupled with its imaging facility over a wide field of view. There are a number of variants, involving liquid crystal alignment (43,44), vacuum evaporation of a metal layer (45,46) and homoepitaxial deposition of a thick LB film (32). Of these, the last is least damaging to the monolayer, least subject to artefacts and least difficult to interpret, and has produced evidence for several types of anisotropic behaviour. 

The nature of the deposit and the rate of nucleation at the very beginning of the deposition are affected, among other factors, by the nature of the substrate. A specific case is that of epitaxy where the structure of the substrate essentially controls the structure of the deposit.Plb lP ] Epitaxy can be defined as the growth of a crystalline film on a crystalline substrate, with the substrate acting as a seed crystal. When both substrate and deposit are of the same material (for instance silicon on silicon) or when their crystalline structures (lattice parameters) are identical or close, the phenomena is known as homoepitaxy. When the lattice parameters are different, it is heteroepitaxy. Epitaxial growth cannot occur if these stmctural differences are too great. 

Green, M. L., Brasen, D., and Luftman, H., High Quality Homoepitaxial Silicon Films Deposited by Rapid Thermal Chemical Vapor Deposition, J. Appl. Phys., 65(6) 2558-2560 (March 1989)... 

For deposition of II-VI compounds, three scenarios for lattice-matched compound substrates are readily available (1) deposition on the compound itself, homoepitaxy (2) deposition on a second II-VI compound that happens to be lattice matched, such as HgTe on CdTe or (3) deposition on a corresponding III-V compound. There are two problems with homoepitaxy—one is why Most of the time there is no need to grow a layer of a compound on a substrate of the same compound. There are cases where the substrate is grown by a method that produces an inexpensive but inferior material, and a high-quality epi layer of the same compound is grown... 

W. Qiu, Y.K. Vohra and S.T. Weir, Role of nitrogen in the homoepitaxial growth on diamond anvils by microwave plasma chemical vapor deposition, J. Mater. Res., 22, 1112-1117 (2007). 

As discussed in Section 6.2.2, previously studied methods for electrodeposition of metal sulfide thin films involve either chemical reactions in solution to form solid particles (TS in water)42,43) or do not allow long-range homoepitaxial crystal growth (S in DMSO),37"",1) so are not suitable for deposition of ordered thin films of useful thickness. If a system where layer-by-layer... 

In molecular beam epitaxy (MBE) [317], molecular beams are used to deposit epitaxial layers onto the surface of a heated crystalline substrate (typically at 500-600° C). Epitaxial means that the crystal structure of the grown layer matches the crystal structure of the substrate. This is possible only if the two materials are the same (homoepitaxy) or if the crystalline structure of the two materials is very similar (heteroepitaxy). In MBE, a high purity of the substrates and the ion beams must be ensured. Effusion cells are used as beam sources and fast shutters allow one to quickly disrupt the deposition process and create layers with very sharply defined interfaces. Molecular beam epitaxy is of high technical importance in the production of III-V semiconductor compounds for sophisticated electronic and optoelectronic devices. Overviews are Refs. [318,319],... 

Epitaxy The deposition of a single-crystal film of a material upon a template of atoms provided by the surface of a crystalline solid called the substrate. Such a film is termed an epitaxial layer If the film and substrate are composed of materials having the same lattice parameter, the film is homoepitaxial," and if the film and substrate are formed from materials with different lattice parameters, the film is heteroepitaxial. ... 

Single crystalline AIN, GaN and InN nanowires illustrated in Fig. 20 can be deposited on Si substrates covered with Au islands by using urea complexes formed with the trichlorides of Al, Ga and In as the precursors.00 Single crystalline GaN nanowires are also obtained by the thermal evaporation/decomposition of Ga.Oj powders with ammonia at 1423 K directly onto a Si substrate coated with a Au film.21 Direction-dependent homoepitaxial... 

Epitaxial metal deposition — In an epitaxial deposition the crystal lattice of the substrate is continued in the deposit. In homoepitaxy the substrate and the growing film... 

Homoepitaxial metal deposition epitaxial metal deposition... 

Several researchers have reported successful deposition of homoepitaxial diamond films on natural as well as HPHT diamond substrates (e.g., 101-104). 

The most important layer growth is the deposition of single-crystal films through either homoepitaxy, in which the deposited film has the same crystal structure and chemical composition as that of the substrate, or heteroepitaxy, in which the deposited film has a close matching crystal structure to that of the substrate. Homoepitaxy is a simple extension of the substrate, and thus there is... 

It has been widely demonstrated that the preparation of oriented, and in some cases epitaxial films by CSD is possible, despite the relatively large thickness of the films that is deposited in a single step. Lange ° reviewed the various mechanisms that lead to oriented growth, and a variety of factors including reactions at the electrode interface, - organic content within the film," " and the use of seed layers" to promote homoepitaxy have been discussed. The ability to control film properties (remanent polarization, dielectric constant, etc.) through manipulation of film orientation has also been shown. 

Figure 8.1. STM images of a homoepitaxial diamond layer surface deposited on single crystal diamond (100) surface [138].

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