Contact Resistances at Nano Interfaces of Conducting Polymers, Poly(3-alkylthiophene) and Metals of Al and Au

Keiichi KANETO  Wataru TAKASHIMA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E87-C   No.2   pp.148-151
Publication Date: 2004/02/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress of Organic Molecular Electronics)
Category: Nano-interfacial Properties
Keyword: 
conducting polymers,  diodes,  junctions,  Schottky junction,  potential profile,  

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Summary: 
Electrical properties of contacts between head-tail coupled poly(3-hexylthiophene), PHT and Al (and Au) in planer type and sandwich type diodes of Al/PHT/Au have been studied. The contact resistances are directly evaluated by probing the potential profile of PHT between the metal electrodes using micromanipulators installed in scanning electron microscope. In the potential profile of planer type diode, a large potential cliff is observed at Al/PHT interface and some appreciable potential step is also found at PHT/Au interface. The contact resistance at the Al/PHT interface deduced from the potential profile shows the bias and its polarity dependence, indicating the existing of the Schottky like junction. At forward bias, it is found that the residual resistance at Al/PHT interface limits the diode performance. The residual resistance is supposed to be insulating layer of Al oxide. At larger reversed bias, the contact resistance at Al/PHT decreased abruptly due to the Zener breakdown. The potential profile of sandwich type diode is similar to that of planer type diode. It is found that even the PHT/Au contact shows the ohmic behavior, the contact resistance is significant as to limit the maximum current of the cells.