Epitaxial lattice match

Moreover, if the fiber is in the crystalline state, as in the case of surface-induced polymer epitaxy, lattice matching between the polymer and fiber crystals provides another favorable situation for transcrystallization. For example, the existence of excellent matching of nylons and iPP with high-modulus graphitic carbon fibers has led to the transcrystallization of nylons and iPP around the carbon fibers [135]. Taking this into account, the case in which both fiber and matrix are of... 

The oriented overgrowth of a crystalline phase on the surface of a substrate that is also crystalline is called epitaxial growth [104]. Usually it is required that the lattices of the two crystalline phases match, and it can be a rather complicated process [105]. Some new applications enlist amorphous substrates or grow new phases on a surface with a rather poor lattice match. 

There are many deposit-substrate combinations where the basic lattice mismatch is very large, such as when a compound is formed on an elemental substrate, but where excessive strain does not necessarily result. Frequently a non one-to-one lattice match can be formed. If a material can match up every two or three substrate surface unit cells, it may still form a reasonable film [16]. In many cases the depositing lattices are rotated from the substrate unit cells, as well. In a strict definition of epitaxy, these may not be considered, however, it is not clear why high quality devices and materials could not be formed. 

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. 

Au is an excellent electrode material. It is inert in most electrochemical environments, and its surface chemistry is moderately well understood. It is not, however, the substrate of choice for the epitaxial formation of most compounds. One major problem with Au is that it is not well lattice matched with the compounds being deposited. There are cases where fortuitous lattice matches are found, such as with CdSe on Au(lll), where the Vs times the lattice constant of CdSe match up with three times the Au (Fig. 63B) [115,125]. However, there is still a 0.6% mismatch. A second problem has to do with formation of a compound on an elemental substrate (Fig. 65) [384-387]. Two types of problems are depicted in Fig. 65. In Fig. 65A the first element incompletely covers the surface, so that when an atomic layer of the second element is deposited, antiphase boundaries result on the surface between the domains. These boundaries may then propagate as the deposit grows. In Fig. 65b the presence of an atomically high step in the substrate is seen to also promote the formation of antiphase boundaries. The first atomic layer is seen to be complete in this case, but when an atomic layer of the second element is deposited on top, a boundary forms at the step edge. Both of the scenarios in Fig. 65 are avoided by use of a compound substrate. 

Growth of various semiconductors onto certain single-crystal substrates has resulted in epitaxial growth in a number of cases. This epitaxy has been well studied for CdS deposition by Lincot et al. [59-63]. Although the epitaxy requires a certain degree of lattice matching between semiconductor and substrate, chemical interactions between the constituents of the deposition solution and the substrate are important as well (discussed in more detail in Chap. 4). It is a reasonable assumption that epitaxial deposition occurs via an ion-by-ion process. Indeed, it has... 

Various investigations into the epitaxial deposition of CdS onto different singlecrystal substrates have been carried out by Lincot et al. On InP, which is closely lattice matched to CdS (<0.1% difference), epitaxial deposition (c-axis of hexagonal CdS perpendicular to the substrate) occurs on the (111) P polar face of the InP but polycrystalline deposition on the (111) In face [49,56]. This difference was clearly due to differing chemical or electrostatic interaction between the InP faces... 

The PbTi03 films were grown epitaxially on SrTiOs (001) substrates as described previously [2], Cation precursors were either titanium isopropoxide (tip) or titanium tertbutoxide (ttb), and tetraethyl lead (tel). The oxidant was O2, with N2 carrier gas. Films were typically deposited at 750°C at a total pressure of 10 Torr (P02 = 2.5 Torr). Under appropriate growth conditions, the PbTi03 films replicated the high crystalline quality of the substrates (0.01° typical mosaic). Films thinner than 40 nm remained lattice matched with the SrTiC>3, while the epitaxial strain was mostly relaxed in thicker films. 

Fig. 2.8. (a) Hall mobility as a function of the temperature for an undoped epitaxial ZnO layer and (b) Hall mobility of Ga-doped ZnO layers as a function of the carrier concentration. The ZnO films were grown epitaxially on lattice-matched ScAlMg04 (SCAM) by Makino et al. [64], In (a) the calculated mobilities for acoustical, polar-optical, piezoelectric, and ionized impurity scattering are shown, together with the total theoretical mobility. In (b) the solid curve is the fit curve (2.24) from Fig. 2.6, while the dashed line is the theoretical curve, calculated by Makino et al. [64]. The dotted line was calculated for transport across depletion regions at grain barriers (see Sect. 2.2.3), also present in epitaxial films [106]... 

Experimental determinations of barrier heights on oxide semiconductor interfaces using photoelectron spectroscopy are rarely found in literature and no systematic data on interface chemistry and barrier formation on any oxide are available. So far, most of the semiconductor interface studies by photoelectron spectroscopy deal with interfaces with well-defined substrate surfaces and film structures. Mostly single crystal substrates and, in the case of semiconductor heterojunctions, lattice matched interfaces are investigated. Furthermore, highly controllable deposition techniques (typically molecular beam epitaxy) are applied, which lead to films and interfaces with well-known structure and composition. The results described in the following therefore, for the first time, provide information about interfaces with oxide semiconductors and about interfaces with sputter-deposited materials. Despite the rather complex situation, photoelectron spectroscopy studies of sputter-deposited... 

In the absence of good quality single crystal samples, the physical properties of indium nitride have been measured on non-ideal thin films, typically ordered polycrystalline material with crystallites in the 50 nm to 500 nm range. Structural, mechanical and thermal properties have only been reported for epitaxial films on non-lattice-matched substrates. 

Narayan (2005) TEM ZnO-sapphire Ge-Si systems Epitaxy and other lattice matching concepts + + n.a. Thin film growth, nanostructuring... 

The MgO(OOl) surface has been the object of numerous studies because it is widely used as a substrate for the epitaxial growth of metals [36-38] and as a model support for dispersed small catalytic particles. It is also used as a substrate to grow high-temperature superconductors because of its close lattice match to YBa2Cu30v.x and its low chemical reactivity. 

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