Electrical and Optical Film Properties

In addition to oxidation and reduction there is a change in the electrical properties between neutral state and metal-like conducting behavior. For investigation of the electrical properties electrochemical impedance spectroscopy is used. The principles of this method were described in Chapters 4 and 5. 

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Shanthi E, Dutta V, Baneqee A and Chopra K L 1980 Electrical and optical properties of undoped and antimony-doped tin oxide films J. Appi. Rhys. 51 6243-51... 

Since multiple electrical and optical functionality must be combined in the fabrication of an OLED, many workers have turned to the techniques of molecular self-assembly in order to optimize the microstructure of the materials used. In turn, such approaches necessitate the incorporation of additional chemical functionality into the molecules. For example, the successive dipping of a substrate into solutions of polyanion and polycation leads to the deposition of poly-ionic bilayers [59, 60]. Since the precursor form of PPV is cationic, this is a very appealing way to tailor its properties. Anionic polymers that have been studied include sulfonatcd polystyrene [59] and sulfonatcd polyanilinc 159, 60]. Thermal conversion of the precursor PPV then results in an electroluminescent blended polymer film. 

Ma, H., et al., Electrical and Optical Properties ofF-doped Sn02 Films Deposited by APCVD, Solar Energy Materials and Solar Ce//5,40(4)371-380 (Aug. 1996)... 

In Section 2.4, the main aspects of the nitrogen-induced structural changes are presented, by the discussion of the most important characterization techniques. This presentation is complemented by an overview of a-C(N) H structure. Finally, in Sections 2.5 and 2.6, respectively, results concerning the mechanical properties, and the electrical and optical properties of a-C(N) H films are presented. As long as possible, they will be correlated with the observed structure changes. 

The question as to why the electrical and optical properties of the anodic film change drastically upon proton insertion could be answered in correlation with UPS investigations (Fig. 28). 

T. Nagamoto, Y. Maruta, and O. Omoto, Electrical and optical properties of vacuum-evaporated indium-tin oxide films with high electron mobility, Thin Solid Films, 192 17-25 (1990). 

A. Salehi, The effects of deposition rate and substrate temperature of ITO thin films on electrical and optical properties, Thin Solid Films, 324 214-218, 1998. 

S. Honda, M. Watamori, and K. Oura, The effects of oxygen content on electrical and optical properties of indium tin oxide films fabricated by reactive sputtering, Thin Solid Films, 281-282 206-208, 1996. 

Since one common use of oxide films is for transparent, conducting coatings, the resistivities of these films were usually measured. Table 2.2 shows some basic electrical and optical properties of some of these films. 

Electrical and optical properties as well as adhesion of many metal films including Pt and Au can be markedly improved by annealing at temperatures up to 600°C in air [55]. These changes are probably manifestations of the coalescence of individual islands into a more continuous film. The effects are particularly pronounced for gold, where the resistivity drops by 30-50% and the optical transparency, as shown in Figure 11.3 [55], improves considerably. Similar effects are observed for Pt [55,57],... 

In conclusion, for both AP-CVD and LP-CVD processes, only a narrow range of temperatures can be identified for optimum performance (a range that is typically 40°C-wide). Within this narrow temperature range highly oriented films are obtained that have electrical and optical properties suitable to act as transparent conductors in solar cells. The typical substrate temperature is around 400°C for the AP-CVD process, whereas it is around 160°C for the LP-CVD process. The two processes yield film orientations that are perpendicular to each other. 

As has been discussed above, there is a strong influence of grain size on the electrical and optical properties of ZnO films. Take as a first example, ZnO films grown by the LP-CVD process in the substrate temperature range between 155 and 180°C they have a microstructure as described in Sect. 6.2.2.1 with conical crystallites that form pyramids at the surface (see Fig. 6.6). This microstructure has, via the pyramidal structure of the surface, a pronounced influence on the optoelectronic properties of the films, specifically on their light scattering capability. 

Kim, K. H., Park, K. C. and Ma, D. Y. (1997). Structural, electrical and optical properties of aluminum doped zinc oxide films prepared by radio frequency magnetron sputtering. J. Appl. Phys. 81(12), 7764-7772. 

Orientation consists of a controlled system of stretching TP molecules in unioriented [unidirectional (UD)] or bioriented [biaxial direction (BD)]. UD orientation can be in the machine direction (MD) or transverse direction (TD).207 Orientation improves strength, stiffness, optics, electrical, and/or other properties with the usual result that improved product performance-to-cost occur. This technique is used during the processing of many different products such as films, sheets, pipes, fibers, tapes, etc. 

Nanto H., Minami T., Orito S. and Takata S., Electrical and optical properties of indium tin oxide thin films prepared on low-temperature substrate by rf magnetron sputtering under an applied external magnetic field, J. Appl. Phys. 63 (1988) pp. 2711-2716. 

Zemel, J. N., J. D. Jensen, and R. B. Schoolar (1965). Electrical and optical properties of epitaxial films of PbS, PbSe, PbTe, and SnTe. Phys. Rev. 140, A330 2. 

Table 1. Summary of the Mechanical,Thermal, Electrical, and Optical Properties of ParyleneThin Films Deposited Using...

Intercalation of electroactive polymers such as polyaniline and polypyrrole in mica-type layered silicates leads to metal-insulator nanocomposites. The conductivity of these nanocomposites in the form of films is highly anisotropic, with the in-plane conductivity 10 to 10 times higher than the conductivity in the direction perpendicular to the film. Conductive polymer/oxide bronze nanocomposites have been prepared by intercalating polythiophene in V2O5 layered phase, which is analogous to clays. °° Studies of these composites are expected not only to provide a fundamental understanding of the conduction mechanism in the polymers, but also to lead to diverse electrical and optical properties. 

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