Vacuum exposure, film structures

In order to demonstrate the importance of the barrier layer for the layer exchange process, an initial glass/Al/a-Si stack without a barrier layer was prepared [50]. To prevent the formation of a barrier layer the a-Si was deposited directly onto the A1 (without vacuum break). The SEM images in Fig. 12.11 make the influence of the barrier layer clear. Two samples are shown - one with barrier layer (by exposure to air for 2 h) (left hand side) and one without barrier layer (right hand side). Both samples were annealed for 45 min at 480° C. After the annealing step, the A1 was etched off chemically. To show the cross section as well as the surface, the samples were tilted by 30° for the SEM measurements. The sample with barrier layer (left) shows a continuous poly-Si film with Si islands on top (similar to what is shown in Fig. 12.5), whereas the sample without barrier layer (right) does not show a continuous poly-Si film but a porous film structure. The former interface between the A1 layer and the a-Si layer is not visible. In some parts, the... 

The panel was produced as follows (Fig. 10.5). A donor film with the structure previously described and coated with a 1-pm DNNSA-PANI/SWNT composite [15] was used to print all conducting circuit elements. First, the large donor film was held by vacuum on the flexible receiver. The gate layer was then printed by selectively exposing the DNNSA-PANI/SWNT donor film as previously described. When exposure was complete the receiver was removed and a l-pm dielectric layer was applied over the whole area. The receiver is then repositioned on to the drum in registry for laser printing of the source/drains and interconnects. The widths of... 

Structural properties. The structure of metallic films can be conveniently determined using x-ray diffraction with a surface reflection pinhole technique in a vacuum camera as indicated in Fig. 20. This device resulted from extensive efforts to develop a camera that could be used to determine the surface orientation of thin metal films with a minimum of manipulation of the instrument, of exposure time and of calculation required to obtain the data on orientation from the diffraction pattern. The film (6) mounted with a Lucite spacer (7) onto the turn table (8) is activated by the shaft (10). The beam (3) enters through the... 

Our experiments show, unambigously, that a pure carbon film rich with sp linear chains can be formed by assembling carbon clusters at room temperature under ultra-high vacuum. Polyyne and polycumulene species are present and stabilized in all-carbon metastable structures without the need of hetero-atom terminal groups. Under He, N2, and H2 exposure the amount of sp species reduces exponentially with time depending upon the mass of the gas. For the investigated gases no chemical interactions have been observed. 

XRD studies show that synthesized composites do not contain any crystal phase, just an amorphous phase. Optical absorption measurements prove that synthesized nanocomposites are containing Ti02 and Ti phases. For comparative analysis the pure Ti containing thin film was deposited onto the cold substrate (77 K) and onto the substrate at room temperature. The same result was obtained XRD analysis shows that the synthesized films only contain the amorphous phase. Kinetics of the electrical resistance increase with the air exposure of Ti/PPX nanocomposites (after synthesis under vacuum) is similar to that of the Al/PPX ones. For a metal content below the percolation threshold the metal particles became insulator within several seconds, whereas for the samples beyond the threshold the observed resistance increase is per cents within several hours. DTA analysis revealed that the heating of amorphous Ti02 nanoparticles up to a temperature of 480°C leads to a phase transformation to anatase, whereas heating up to 580°C results in the anatase transformation to the mtile structure. 

Further, conductivity measurements were carried out at Covion Organic Semiconductors on specially designed substrates with interdigital structures. Film thicknesses were in the order of 100 nm. The resistance was measured under vacuum to avoid exposure of the somewhat hygroscopic films to humidity. The current was measured for voltages of —10—hlO V, the resistivity was then calculated from the slope of the straight lines. The reproducibility was very good. 

In a UPS study by Fujimoto et al,[8I], the effects of air and temperature on the electronic structure of chemically and electrochemically prepared solution-cast poly(3-alkylthiophene) films were investigated. It was found that the threshold energy was almost identical for the different solution-cast films. However, electrochemically, as-prepared films had a smaller threshold value by about 0.3 eV. Changes in the work functions (of about 0.2 eV) of the samples were observed upon heating in vacuum. Subsequent recovery upon exposure to air was attributed to dedoping and doping effects caused by oxygen. 

Perylenes are microcrystalline solids and polymorphism has been reported. For instance, depending on the sample history, XXa was shown to form four different polymorphs as powders [235]. Perylene XlXm forms an amorphous thin film when prepared by die vacuum deposition technique. Upon exposure of the amorphous thin film to solvent vapor, a crystalline thin film is obtained [246]. Detailed structural characterization of these polymorphs and the connectivity of the structural changes to the photoconductivity have yet to be detailed. 

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