Thin films structural evolution

Figure 2.16. (a-c) Simulations of film structural evolution for PZT thin films at various times during heat treatment.15 (d) A representative SEM photomicrograph illustrating the columnar microstructure of PZT.48 The lower layer is the lower Pt electrode, the middle layer is the PZT, and the upper layer is the top Pt electrode, [(a)-(c) Reprinted with permission from Ref. 15. (d) Reprinted with permission from Ref. 9. Copyright 1997 American Chemical Society.] (See color insert.)... 

Schwartz, R. W. Dobberstein, H. 2003. Modeling structural evolution in ferroelectric thin films. Proc. 11th US-Japan Seminar on Diet. Piezo. Ceram. (Sapporo, Japan), pp. 215-218. 

Coffman, P. R. Barlingay, C. K. Gupta, A. Dey, S. K. 1996. Structure evolution in the Pb0-Zr02-Ti02 sol-gel system Part II—pyrolysis of acid and base-catalyzed bulk and thin film gels. J. Sol-Gel Sci. Tech. 6 83-106. 

C. Mattevi, G. Eda, S. Agnoli, S. Miller, K.A. Mkhoyan, 0. Celik, et al., Evolution of electrical, chemical, and structural properties of transparent and conducting chemically derived graphene thin films, Advanced Functional Materials, 19 (2009) 2577-2583. 

Details about preparation and characterization of dispersed microcrystals can be found in review chapters [322] and will not be dealt with here. All investigations indicate that the properties of microcrystals differ considerably from those of bulk metals (and from those of adatoms and thin films as well) [328], and that they can also be influenced by the nature and texture of the support. In particular, micro-deposits of precious metals on various inert supports (Ti, Ta, Zr, Nb, glassy carbon etc.) exhibit enhanced electrocatalytic effects as evaluated per metal atom, while the mechanism of H2 evolution remains the same [329], and the enhancement increases as the crystallite size decreases [326, 331] (Fig. 17). However, while this is the case with Rh, Pt, Os and Ir, Pd shows only an insignificant increase, whereas for Ru even a drastic decrease is observed [315, 332]. Thus, the effect of crystal size on the catalytic activity appears to depend on the nature of the catalyst (without any relation with the crystal structure group) [330]. 

Extended X-ray Absorption Fine Structure) technique, concerning nanocrystalline materials, is reviewed. The potentialities of the technique to characterise hulk materials, thin films, and structural evolution during the preparation of nanoparticles using in situ set-ups are presented. 

Oda et al. observed that the spots of the diffraction patterns of AP-CVD ZnO films grown with DEZ and alcohols become sharper as the thickness of the ZnO film increases [14]. This is a further indication that the crystallites become larger as the thickness of the ZnO films is increased (in this case, also, only the (0002) peaks are visible in the XRD diffraction pattern). LP-CVD ZnO The evolution of the structural properties of LP-CVD ZnO thin films with their thickness has been comprehensively investigated in [17] and is presented in detail hereafter. 

This chapter reviews the general aspects of the CSD method for ferroelectric thin-film preparation, with attention given to precursors, solution chemistry, and process development. An additional focus of the chapter is on the structural evolution of the solution precursor into the crystalline (typically perovskite) state and the impact of precursor chemistry and film fabrication conditions on the transformation process. Lastly, the chapter reviews the advantages and disadvantages of the CSD method and discusses industrial implementation of the technique. 

We will present some results obtained by electrodepositing thin films of Cu, Co and Ni on silicon. Emphasis will be given to different aspects on each case, namely, the morphology and growth rate of copper thin layers, hydrogen evolution during cobalt deposition and structure and electrical properties of nickel layers. 

It was shown that thin films of Cu, Co and Ni could be successfully deposited onto Si substrates, without the need of a seed layer. For all three metals, uniform layers with a compact and granular morphology could be obtained. From RBS data the deposition rates as well as the current efficiencies could be determined. For Co films it was shown that addition of boric acid caused the evolution of hydrogen. On the other hand, it was possible to improve the current efficiency of electrolytes containing boric acid by increasing the concentration of cobalt sulfate in the bath. For Ni films electrodeposited from a highly concentrated sulfate electrolyte, it was observed the formation of texture in the (220)-direction. Electric measurements performed on Ni/n-Si structures yielded values for Schottky barriers which are comparable to the ones obtained for junctions fabricated by vapor deposition. 

The evolution of nitrogen on photolysis of the aryIdiazonium salts appears to have limited the use of these systems to thin film applications such as container coatings and photoresists (23). Other efficient photoinitiators that do not produce highly volatile products have been disclosed (24-27). These systems are based on the photolysis of diaryliodonium and triarylsulfonium salts. Structures I and II, respectively. These salts are highly thermally stable salts that upon irradiation liberate strong Bronsted acids of the HX type (Reactions 43 and 44) that subsequently initiate cationic polymerization of the oxirane rings ... 

Investigations have been made of the photodecomposition of thin films of ( 3)2 [95, 96, 120, 121]. In the following discussion the salient results and conclusions of such investigations are presented and compared with those already presented for single crystals. Included is a brief discussion of the structure and perfection of films. The primary emphasis is again on optical studies with only peripheral mention made of the gas-evolution phenomena which are discussed in Section E. 

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