Effects of dopants and copolymerization on Schottky barriers of polypyrrole and polyindole/metal interfaces |
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Authors: | Samaneh Mozaffari Mohammad Reza Nateghi Abbas Behjat Mahmood Borhani-Zarandi |
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Affiliation: | 1. Department of Physics, University of Yazd, Yazd, P.O. Box 89195-741, Iran 2. Department of Chemistry, Yazd Branch, Islamic Azad University, Yazd, Iran
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Abstract: | Schottky-barrier diode devices were fabricated in a sandwich configuration with poly(pyrrole-co-indole) copolymer semiconducting films prepared by electropolymerization. Effect of different dopants of ClO4 ?, BF4 ?, C7H7SO3 ? and [Fe(CN)6]3? on the electronic properties of the fabricated devices was followed using Ag, In, Al and Cu metal junctions. Current?Cvoltage and capacitance?Cvoltage characteristics were recorded for making a comparative evaluation of the electronic and junction properties of the devices. The electrical characteristics of the junctions were analyzed based on the standard thermionic emission theory. Polymer doped by ClO4 ? showed lower reverse saturation currents and ideality factor but higher potential barriers and rectification ratios. Effect of dopant ions and copolymerization on the optical band gaps (E g) of the films were investigated and the optical transmissions of the doped copolymer films were measured in the wavelength range of 250?C900?nm. It was shown that the energy gap of copolymers laid between those of corresponding homopolymers and polyindole (PIN) doped by [Fe(CN6)]?3 had E g less than that of polymer doped by other anions whereas E g of polypyrrole was independent of dopant ions. Also, the morphology of the polymeric films revealed the surface of the PIN doped with ClO4 ? was very smooth which created a good contact with indium metal. |
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