Polycrystalline thin orientation

However, the derived value for Ei is usually termed the activation energy E and may contain other contributions in addition to the intrinsic Ei value, such as those arising from the orientation and morphology of the sample. For this reason E is most commonly used. In the case of polycrystalline thin hlms, grain boundaries may have a dominant effect, as will be discussed in Section 6.4, where examples of intrinsically metallic materials behaving as semiconductors will be given. 

A polycrystalline thin film does not have any preferred orientation (Figure 6.4 (c)). In such a case, the diffraction from the crystal is not a spot but a so-called Debye-Scherrer ring. Therefore, the sample does not have to be inclined to obtain the diffraction pattern. Conventional 2 0-6 scans move the scattering vector H in the radial direction along the film surface normal. Thus, these scans give sufficient information when the film is polycrystalline. The obtained diffracted intensity must be corrected in terms of the absorption and the Lorentz polarization. These two terms and the obtained diffracted intensity have the following relation ... 

The substituted five-ring OPVs have been processed into polycrystalline thin films by vacuum deposition onto a substrate from the vapor phase. Optical absorption and photoluminescence of the films are significantly different from dilute solution spectra, which indicates that intermolecular interactions play an important role in the solid-state spectra. The molecular orientation and crystal domain size can be increased by thermal aimealing of the films. This control of the microstructure is essential for the use of such films in photonic devices. 

Figure 7.3. Observation at a low incidence angle of a polycrystalline thin film in which the crystals are randomly oriented...

Spray pyrolysis technique has been used to deposit polycrystalline thin films comprising of CuInSa nanocrystals onto glass substrates. p-XRD studies demonstrate that the films have a chalcopyrite structure with preferred orientation along (112) lattice plane. Average diameter of the nanocrystals, as determined by SEM and TEM images, was found to be about 40-60 nm while band gap calculated through optical absorption studies was found to be 1.55 eV. A solar device fabricated by using these films demonstrated a power conversion efficiency of 7.60%. 

Nason et al. [20] reported that polycrystalline thin films (1-10 /am) of the nonlinear material 2-methyl-4-nitroaniline were deposited on Ag, Cu, and Si by conventional and ionized cluster beam deposition. The use of ions was found to promote a highly oriented film, with only a single x-ray diffraction orientation (112) being observed at reduced temperatures (-50 C). The effect of the ions on the physical microstructure of the films was to densify the film and reduce the size of the microcrystals. The films had powder-like optical properties and displayed a strong second harmonic from an N YAG laser. 

Fig. 13 Three-step procedure for the morphosynthesis of nacre-type laminated CaCOs coatings. In the first step, an amorphous highly hydrated CaCOs thin film is deposited on a glass substrate. Upon heating, this precursor film is transformed into a polycrystalline thin film consisting of a mosaic of flat single-crystalline calcite domains. In the last step, highly oriented single and multiple layers of calcite crystals are grown epitaxially on the underlying polycrystalline thin film. Reproduced from [235] with permission of Wiley...

The results for characterizing stress in elastically anisotropic cubic single crystal films presented in Section 3.5 and in this section can also be adapted, under appropriate conditions, for textured polycrystalline films. An equi-biaxial mismatch strain in the (001) or (111) textured thin film of a cubic crystal results in an equi-biaxial mismatch stress. Because the response is transversely isotropic, the biaxial moduli derived for cubic crystals of these orientations can also be used to characterize polycrystalline thin... 

Thin oriented and polycrystalline R films on oriented substrates. 

The external manifestation of reorientation relaxation under an applied stress is the anelastic strain that accompanies a net change of orientational order. In contrast to the elastic strain, the anelastic strain develops in a time-dependent manner governed by the rate of the reorientation jump. Under a static stress, the relaxation may therefore be observed as a limited (and recoverable) creep process. Frequently, however, it is more desirable for reasons of sensitivity or convenience to observe the relaxation dynamically as a loss-peak, via internal friction measurements made as a function of temperature and/or vibration frequency. Figure 2 shows the oxygen Snoek peak in polycrystalline thin film niobium, tested in the same vibrating-reed apparatus" - used for our studies of... 

Figure 4-150 shows the major components and design of the PDC bit. The polycrystalline diamond compacts, shown in Figure 4-151. The polycrystalline diamond compacts (of which General Electric s) consist of a thin layer of synthetic diamonds on a tungsten carbide disk. These compacts are produced as an integral blank by a high-pressure, high-temperature process. The diamond layer consists of many tiny crystals grown together at random orientations for maximum strength and wear resistance.

EDSA of thin polycrystalline films has several advantages First of all the availability of a wide beam (100-400 pm in diameter) which irradiates a large area with a large amount of micro-crystals of different orientations [1, 2]. This results into a special t5q)e of diffraction patterns (DP) (see Fig.l). Thus it is possible to extract from a single DP a full 3D data set of structure amplitudes. That allows one to perform a detailed structure analysis with good resolution for determining structure parameters, reconstruction of ESP and electron density. 

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