Epitaxy heteroepitaxy

Epitaxy Oriented overgrowth of an atomistically deposited film. See also Epitaxial growth Epitaxy, heteroepitaxy Epitaxy, homoepitaxy. 

Epitaxy, heteroepitaxy Oriented overgrowth on a substrate of a different material or the same material with a different crystalline structure. Example Silicon on sapphire. 

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. 

Fundamental to forming high quality structures and devices with thin-films of compound semiconductors is the concept of epitaxy. The definition of epitaxy is variable, but focuses on the formation of single crystal films on single crystal substrates. Homoepitaxy is the formation of a compound on itself. Heteroepitaxy is the formation of a compound on a different compound or element, and is much more prevalent. 

MBE (molecular beam epitaxy), which involves epitaxial growth of thin films on either the same material as substrate (homoepitaxial) or a lattice-matched substrate (heteroepitaxial) the heated substrate reacts with a molecular beam of compounds containing the constituent elements of the semiconductor as well as any dopants the resultant film is essentially a single crystal slow growth rates produce films from a few nanometers thick to at most several hundred nanometers that have very high purity and controlled levels of dopants. 

Epitaxial thin films, 24 742 Epitaxy, 22 152, 185. See also Epitaxial growth Heteroepitaxy in FET fabrication, 22 163-164 in HBT fabrication, 22 166, 167 in RTD fabrication, 22 170 silicon purification via, 22 496 197 vitreous silica in, 22 442 Epitaxy crystallization, ion-beam-induced, 14 447-448... 

The surface cleaning of the CIS also affected the mode of deposition of the CdS. The CdS was found to grow to a greater or lesser extent of epitaxy on single-crystal (heteroepitaxial layer) CIS [22]. Very good epitaxy of cubic CdS was found for cyanide-treated CIS somewhat lower epitaxy was found for ammonia-treated surfaces and poorer epitaxy obtained for untreated surfaces that contained considerable oxides. Additionally, the epitaxy was only obtained at higher deposition temperatures (>70°C) at lower temperatures, the growth was polycrystalline. 

During the growth of solid solutions (e. g., pseudobinary alloys and doped compounds), the melt composition at the interface can be a function of time, a situation that results in a natural composition gradient in the growth direction. Heteroepitaxy, the growth of an epitaxial film with a composition different from that of the substrate, is more difficult compared with other... 

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],... 

H. Brune and K. Kern, Heteroepitaxial metal growth The effects of strain, in Growth and Properties of Ultrathin Epitaxial Layers, Vol. 8 of The Chemical Physics of Solid Surfaces and Heterogeneous Catalysis, eds. D. A. King and D. P. Woodruff (Elsevier Science, Amsterdam, 1997), p. 149. 

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. ... 

In general, unlike for the perfect epitaxial structures of fully strained materials, for nitride heteroepitaxial layers it is essential to perform not a single scan for a symmetrical reflection, but a set of two- or even three-dimensional maps of symmetrical and asymmetrical reflections. Additionally, for some applications, an intense beam is needed and therefore low-resolution X-ray diffractometry can be sometimes a preferable technique to the commonly used high-resolution XRD. For example, if we examine a heterostructural nitride superlattice, low resolution diffractometry will give us a broader zeroth-order peak (information on the whole layer) but more satellite peaks (information on the sublayers). Therefore, multipurpose diffractometers with variable configurations are the most desirable in nitride research. 

B2.3 Epitaxy of III-N layers on GaN substrates B2.4 Alternative oxide substrates for GaN heteroepitaxy B2.5 Cubic substrates for growth of GaN and related compounds... 

The mineral spinel, MgA Of, was one of the first substrates tried for GaN epitaxy [8,25,35], and has been the most successful of all alternative substrates for GaN heteroepitaxy. Spinel single crystals can be grown by the Czochralski technique and substrates of modest size can be obtained commercially. The chief advantage of spinel over sapphire is that it cleaves more easily than sapphire. 

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