Epitaxial growth modes

Perhaps the best examples to illustrate the analysis strength of XPD and AED are the epitaxial growth modes of deposited overlayers. Here, the structure and chemistry of an overlayer, or the new interface, will influence the properties of the film. To control such effects, an understanding of the basic structure and chemistry is essential. Epitaxial Cu on Ni (001) is an excellent example for demonstrating the... 

The second dimer-opening mode observed resulted when a surface atom diffused to the site of a surface dimer and bumped a nearby atom into the center of the dimer. This mechanism resulted in atoms which occupied lattice sites, and produced a surface dimer which remained open for the course of the simulation. Because the final atomic positions corresponded to lattice sites, and because a high rate of surface diffusion was required to produce the bump , this mechanism was associated with the high-temperature epitaxial growth mode identified by Gossmann and Feldman. 

Rosenfeld, G., Poelsema, B., and Comsa, G., Epitaxial growth modes far from eqnihhrinm, in The Chemical Physics of Solid Surfaces, Vol. 8, ed. D.A. King and... 

Table 7.1 Three modes of growth mechanisms in epitaxial growth and corresponding conditions ...

The growth kinetics describes the nucleation processes on the atomic scale. Thermally activated processes as adsorption, desorption, and diffusion at the surface and in the volume, nucleation, and crystallization/ recrystallization determine the film structure and can be controlled by the substrate temperature and the growth rate. Using a diagram ln(J ) over 1/ T, R being the deposition rate and T the growth temperature, three different growth modes (epitaxial, polycrystalline, and amorphous) can be... 

Epitaxial metal deposition — Figure. Schematic representation of heteroepitaxial growth modes... 

It is of some interest to consider the situation where one of the ideahzed 2D systems that have been addressed can be followed in a layer-by-layer growth mode from a strictly 2D plane to one that is more 3D like. Such is the situation in the formation of multilayer molecular films adsorbed to uniform substrates or where epitaxial metal or soft matter growth is realized in chemical vapor deposition, molecular beam epitaxy or polymeric deposition systems. The hneshape discussion above has to be modified to account for the development of the third dimension of order in the system. Conceptually this is rather straightforward. Instead of considering, as Warren did, an ideal 2D reciprocal lattice composed of an ordered array of uniform rods, the reciprocal lattice for an idealized multilayer (e.g., two to five individual layers) system is characterized by... 

The structures with self-organized GaN/AlN QDs were grown by molecular beam epitaxy (MBE) on (0001) sapphire substrates. Ammonia was used as the source of active nitrogen. A single layer of GaN QDs was formed on the AIN buffer surface by a particular MBE growth mode at relatively low substrate temperatures (Ts 540°C). A beam equivalent pressure (BEP) of gallium flux was 5.4T0 Torr and BEP of ammonia flux was 10" Torr. To obtain GaN QDs... 

The atomistic theory becomes of additional significance for the transition from 2D Me phase formation in the UPD range to 3D Me phase formation in the OPD range. Experimental results obtained using modern in situ techniques with lateral atomic resolution showed that the transition phenomena can only be interpreted on the basis of atomistic approaches. The UPD surface modification turns out to be a more general phenomenon affecting not only the nucleation processes but also the growth mode and epitaxy of 3D metal phases. 

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