Epitaxial crystallization, method

Epitaxial crystal growth methods such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) have advanced to the point that active regions of essentially arbitrary thicknesses can be prepared (see Thin films, film deposition techniques). Most semiconductors used for lasers are cubic crystals where the lattice constant, the dimension of the cube, is equal to two atomic plane distances. When the thickness of this layer is reduced to dimensions on the order of 0.01 )J.m, between 20 and 30 atomic plane distances, quantum mechanics is needed for an accurate description of the confined carrier energies (11). Such layers are called quantum wells and the lasers containing such layers in their active regions are known as quantum well lasers (12). 

Alternative methods, including friction transfer [71] and directional epitaxial crystallization [76], have also been used successfully in the alignment of PFs. In the friction transfer method one provides a crystalline templating substrate, (e.g., PTFE) and then applies a CP over layer. As in the case of a rubbed substrate, the CP does not significantly impact the orienting ability of the aligned substrate. This process is commonly referred to as graphoepitaxy. 

Advances in epitaxial crystal growth methods make it possible to prepare heterostructures with essentially arbitrary thiekness of the small-gap layer. When the thickness of this layer is reduced to dimensions of the order of 10 nm (between 20 and 30 atomic planes) a quantum mechanical description of the confined carriers is needed. Such heterostructures are called quantum wells [41. 42]. 

Epitaxial crystallization is one of the few methods that make it possible to control by nonmechanical means and under appropriate processing conditions the morphology and/or structure of crystalline polymers. Furthermore, it may generate single crystalline, although multilamellar, polymer morphologies. 

The formation mechanism is illustrated in Fig. 5. CNT film has also been found to grow epitaxially on the surface of a (3-SiC crystal particle [29], The present method should prove to be applicable to flat panel displays or to electronic devices utilising MWCNTs,... 

In 1985 Car and Parrinello invented a method [111-113] in which molecular dynamics (MD) methods are combined with first-principles computations such that the interatomic forces due to the electronic degrees of freedom are computed by density functional theory [114-116] and the statistical properties by the MD method. This method and related ab initio simulations have been successfully applied to carbon [117], silicon [118-120], copper [121], surface reconstruction [122-128], atomic clusters [129-133], molecular crystals [134], the epitaxial growth of metals [135-140], and many other systems for a review see Ref. 113. 

An important method for producing semiconductor layers is the so-called molecular beam epitaxy (MBE) (see [3,12-14] and [15-19]). Here, atoms of the same or of a different material are deposited from the vapor source onto a faceted crystal surface. The system is always far from thermal equilibrium because the deposition rate is very high. Note that in this case, in principle, every little detail of the experimental setup may influence the results. 

Numerous works have been implemented on tellurium electrochemistry and its adsorption at metal surfaces. The morphological structures of electrodeposited Te layers at various stages of deposition (first UPD, second UPD, and bulk deposition) are now well known [88-93]. As discussed in the previous paragraphs, Stickney and co-workers have carried out detailed characterizations of the first Te monolayer on Au single-crystal surfaces in order to establish the method of electrochemical atomic layer epitaxy of CdTe. 

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