Thin films structure/morphology

Ostoja, P. et al., FET device performance, morphology and X-ray thin film structure of... 

Similarly, Wang and coworkers [271] reported that hyperbranched dendritic structures possessing poly(3-alkylthiophene) arms self-assemble into thin films with morphological features, as well as electrical and optical properties that reveal a surprising degree of structural order. Typical conductivities varied between 42 and 65 sec/cm. 

The structural picture of ionomer in catalyst layers, unraveled in this section, suggests that extrapolation of bulk membrane properties in terms of water uptake, water binding, and proton transport skews specific properties of ionomer in CLs and is not generally feasible for the purpose of CL modeling. One needs to adapt mechanisms of water and proton transport to the thin-film ionomer morphology, where (i) proton transport is dominated by surface properties of ionomer and (ii) electrocatalytic properties are determined by the interfacial thin-film structure formed by Pt/C surface, ionomer film, and a thin intermediate water layer. 

Phase morphologies of immiscible binary homopolymer blends evolve from circular domains of one phase dispersed in the matrix of another through a bicontinuous domain structure to the inverse case of the former [106], When a blend is deposited in thin films, its morphology is also affected by interactions of the polymers constituting the blend with the film interfaces. 

High resolution electron microscopy has recently demonstrated the capability to directly resolve the atomic structure of surfaces on small particles and thin films. In this paper we briefly review experimental observations for gold (110) and (111) surfacest and analyse how these results when combined with theoretical and experimental morphological studies, influence the interpretation of geometrical catalytic effects and the transfer of bulk surface experimental data to heterogeneous catalysts. 

Blockcopolymer microphase separation [9] Depending on the length of chemically different blocks of monomers in a block copolymer, ordered nanostructures can be obtained in bulk samples and thin films. The film morphology can differ significantly from the bulk morphology, but because the structure is determined by the pair-pair interaction of monomers and/or an interface, and it is a thermodynamically stable structure, it is classified as self-assembly. 

Laser ablation of polymer films has been extensively investigated, both for application to their surface modification and thin-film deposition and for elucidation of the mechanism [15]. Dopant-induced laser ablation of polymer films has also been investigated [16]. In this technique ablation is induced by excitation not of the target polymer film itself but of a small amount of the photosensitizer doped in the polymer film. When dye molecules are doped site-selectively into the nanoscale microdomain structures of diblock copolymer films, dopant-induced laser ablation is expected to create a change in the morphology of nanoscale structures on the polymer surface. 

The case of isotactic polypropylene (iPP) presents some differences with respect to those just discussed. While both sPP and PET adopt in their mesophases disordered, extended, essentially non-helical conformations, iPP is characterized by a unique, relatively well ordered, stable chain structure with three-fold helical symmetry [18,19,36]. More accurately we can state that an iPP chain segment can exist in the mesophase either as a left handed or as the enantiomeric right-handed three-fold helix. The two are isoener-getic and will be able to interconvert only through a rather complex, cooperative process. From a morphological point of view Geil has reported that thin films of mesomorphic iPP quenched from the melt to 0 °C consist of... 

Fig. 29 Fractured morphology of spherulitic objects in a thin film of PET crystallized at 220 °C [36]. On the fractured surface many small particles with a diameter of 0.2 0.3 xm are seen while on the spherulite surface there is a fibril structure 0.2 05 xm thick... 

A systematic comparative study of triblock terpolymers in the bulk and thin-film state was carried out on polystyrene-fo-poly(2-vinyl pyridine)-b-poly(ferf-bulyl methacrylate), PS-fr-P2VP-fr-PfBMA. A diblock precursor with a minority of PS leading to a double gyroid structure was used. Upon increase of PfBMA content this morphology changed from lamellae with... 

The work described here is concerned with the development of electrochemical methodologies to grow compound semiconductors with nanoscale or atomic layer control. That thin-films of some compounds can be formed electrochemically is clear. The questions are how much control over deposit composition, structure and morphology can be obtained What compounds, and of what quality, can be formed ... 

Kale, R. B. Lokhande, C. D. 2005. Influence of air annealing on the structural, morphological, optical and electrical properties of chemically deposited ZnSe thin films. Appl. Surf. Sci. 252 929-938. 

Thin films of metals, alloys and compounds of a few micrometres thickness, which play an important part in microelectronics, can be prepared by the condensation of atomic species on an inert substrate from a gaseous phase. The source of the atoms is, in the simplest circumstances, a sample of the collision-free evaporated beam originating from an elementary substance, or a number of elementary substances, which is formed in vacuum. The condensing surface is selected and held at a pre-determined temperature, so as to affect the crystallographic form of the condensate. If this surface is at room temperature, a polycrystalline film is usually formed. As the temperature of the surface is increased the deposit crystal size increases, and can be made practically monocrystalline at elevated temperatures. The degree of crystallinity which has been achieved can be determined by electron diffraction, while other properties such as surface morphology and dislocation structure can be established by electron microscopy. 

The PL spectra of the PFs show well-resolved structural features with maxima at 420,445, and 475 nm assigned to the 0-0, 0-1, and 0-2 intrachain singlet transition, respectively (the 0-0 transition, the most intense) [247]. Due to the tail emission spectrum of PFs, the thin films emit bright sky-blue light. The QE of the PFs is very high, typically in the range of 40 to 80% and, as shown for PFO 196, it depends substantially on the morphology of the polymer [248]. 

One of the major benefits of the ECALE methodology is that it breaks compound electrodeposition into a series of identical cycles and each cycle into a set of individual steps. Each step is examined and optimized independently, resulting in increased control over deposit structure, composition, and morphology. Better understanding of the individual steps in the deposition mechanism should allow the electrochemical formation of high-quality thin films of compound semiconductors. 

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