Texture-oriented films

Figure Ic. DP of textured type films. Micro-crystallites are oriented along one direction...

Figure 7.19 shows PL spectra recorded at 2K for 2.2, 0.7, and 1.5 pm thick PLD ZnO films on a-plane, c-plane, and r-plane sapphire, respectively [63], The full widths at half maximum (FWHM) of the most intense bound exciton peaks are 1.4, 1.7, and 2.6 meV for a-, c-, and r-sapphire, respectively. The film on a-plane sapphire shows the narrowest FWHM among the films under investigation and the free A-exciton (Xa) is most clearly resolved, thus indicating best structural properties of ZnO on a-plane sapphire. The ZnO films on a- and c-plane sapphire grow c-axis textured, whereas films on r-plane sapphire grow a-axis oriented with the ZnO c-axis being in-plane, as demonstrated already in Fig. 7.4. The PL spectrum of the film on r-plane sapphire shows no phonon replica, probably due to the changed ZnO orientation.

Figure 5.7. Growth orientation (film texture) and film morphology [84].

A SEM image of diamond particles is shown in Figure 9.15. Unlike past works, diamond film surfaces were well facetted with (111) and (100) faces, or consisted of cubo-octahedrons. Under certain conditions, either (111) or (100) faces of diamond particles were nearly parallel to the substrate surface. It is of intrigue that the (1 ll)-oriented diamond grains have hexagonal faces, as seen in Figure 9.15, rather than triangles that were seen in Refs. [186, 187]. Thus, both (111)- and (100)-textured diamond films were demonstrated to be synthesized on poly-crystalline Cu foils. 

In the UPS measurements we were able to prepare the (SN)x films inside of the LHV chamber. X-ray analysis and electron reflection patterns show the (102) plane of (SN)x to lie parallel to the substrate plane in a textured orientation. 

The microstructure (texture, orientation) and morphology of diamond films can be controlled by varying the growth parameter a (a=(vioq/vj j j) ), which depends primarily on gas composition and substrate temperature. For fiber-textured films, at low CH4 concentrations and increasing substrate temperatures (a < 1.5), the films exhibit pronounced <110> texture at medium CH4 concentrations and substrate temperatures (1.5 < a < 3), a transition of the fiber axis from <110> to <100> occurs a further increase in CH4 concentrations or decrease in substrate temperatures (a > 3) leads to fine-grained, non-faceted films. 

B. R. Stoner, S. R. Sahaida, J. P. Bade, P. Southworth, and P. J. Ellis, Highly oriented, textured diamond films on silicon via bias-enhanced nucleation and textured growth, J. Mater. Res., 8(6) 1334-1340 (1993)... 

The preferentially oriented films on YSZ substrates exhibit extremely sharp resistive transition with zero resistance obtained at temperatures of 90 K and above. Typical resistivity vs temperature results are shown in Fig. 6 for a 1 pm thick film. The 10-90% transition width is 1.5 K and zero resistance is obtained at 91.4 K. On some films we have observed zero resistance at temperature as high as 94 K, which is one of the highest values reported for films of 1-2-3. When the films are reacted for a longer period to convert all the BaFj, the transition gets broader, with zero resistance obtained at 80-85 K. The critical current density (J,) of films with T,(R=0) higher than 90 K is about 10 A/cm at 77 K and 10< A/cm at 4 K. Films with broader transitions, which are also less textured, have critical current densities an order of magnitude lower. 

Atomically resolved STM studies require preparation of a flat surface with well-defined crystallography. Studies to date have focused on either singlethin film noble metal electrodes. The haditional approach to single-crystal preparation involves growing an ingot or boule by solidification from a melt using a seed crystal to control the orientation. Alternatively, a remarkably simple and inexpensive technique has been developed whereby a H2-O2 flame is used to melt the end of a polycrystalline... 

Lamellar orientation in thin films of a model diblock copolymer with symmetric poly(styrene)- -PLLA (PS-PLLA) was investigated by Chen et al. [62] in the molten state on silicon wafer supported surfaces. Stretching and compression were apt to induce orientation of PLA. Pluta and Galeski [63] studied the plastic deformation of amorphous and thermally noncrystallizable 70/30 PLA/PDLLA induced by plane strain compression in a channel die. The results revealed that plastic deformation transformed an amorphous PLA or PDLLA (thermally noncrystallizable) into a crystalline fibrillar texture oriented in the flow direction. 

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... 

---