Molecular devices based on conducting polymers

5 Molecular Devices Based on Conducting Polymers 13.5.1 Diodes 

Heterojunctions have recently been fabricated using electrochemically prepared polypyrrole and metal (indium, titanium, aluminium and tin). It has been revealed that carrier concentration, estimated as 1.5 x 10 and 5 x 10 in doped and undoped polypyrrole samples, respectively, plays an important role in controlling the junction 

It has been recently revealed that it is possible to fabricate all vacuum deposited metal (Pb, Al, In, Sn)/polyaniline/metal Schottky devices [101]. It has been shown that the barrier height and the ideality factors determined are dependent on the work function of the metal used in the fabrication of these devices. The improved ideality factor obtained as 1.2 for an Al/polyaniline/Ag device has been attributed to more intimate contact of the metal with the vacuum deposited polyaniline electrode. 

Poly(3-methylthiophene) was prepared using an electrochemical technique to fabricate silicon-based devices [102]. From the results obtained using current-voltage measurements, chronopotentiometery, SEM and FTIR techniques, it has been seen that the rectifying behaviour was induced by covalent bond formation between poly(3-methylthiophene) and the silicon. 

Schottky devices have recently been fabricated by thermal evaporation of indium on polyaniline, poly(o-anisidine) and poly(aniline-co-or oanisidine), respectively [103]. The values of the rectification ratio, the ideality factor and the barrier height of an indium/poly(o-anisidine) have been experimentally determined as 300,4.41 and 0.4972, respectively. The observed deviation from the Schottky behaviour for these devices seen at higher voltages has been explained in terms of either the Poole-Frenkel effect or due to the presence of a large number of defects containing the trapped charges existing at the indium/poly (aniline-co-or oanisidine) interface. 

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See also in sourсe #XX -- [ , , , , , , , , , , , , , , , , , ]

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