Electrical stability semiconductor devices

The problem that remains in all cases is the mechanical and electrical stability of the contact achieved between the metal oxide and the metal. To obtain very stable devices, there must be a good and reliable electrical contact, with a low and stable contact resistance. This is because the metal semiconductor junction that forms at the interface between the metal oxide... 

There are, however, several fields of current research in which a corresponding level of understanding would be of interest also for large molecular adsorbates. For example, adsorbate-substrate interactions are relevant in the general areas of biocompatibility [51] and chemical sensors [52]. The requirement of dye-sensitization of metal oxide semiconductors also makes this an important aspect of many molecular photovoltaic devices. In fact, a good interfacial contact between dye and substrate, characterized by long-term stability and intimate electric contact, is vital for the efficiency of e.g. the dye-sensitized solar cells which have been at the center of our attention for the last five years. 

The success of polymer semiconductors in the marketplace, however, depends critically on the ability of these materials to sustain their electrical performance under operation - unstable devices are of little practical use. In this chapter we will describe known issues in the stability of polymer TFTs and point out some of the challenges that must be addressed in the future development of these materials. 

Aromatic hydrocarbon pentacene is important for application in OTFTs as it has superior field effect mobility, good semiconducting behavior, and stability [153], The chemical structure is shown in Fig. 6.10. Pentacene semiconductor films can be fabricated by sublimation in a vacuum deposition system. Optimization of the fabrication parameters, such as the substrate temperature and deposition rate, can yield a highly ordered pentacene film with improved device performance. Oriented films have optical and electrical anisotropies. 

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