Electrical Properties of Junctions between Aluminium and POLY (3-(2,5-Dioctylphenyl)-Thiophene) (PDOPT)
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Date
1998-06
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Addis Ababa University
Abstract
This thesis is based on the study of interface properties between a reactive metal and a neutral
conjugated polymer. The polymer used is poly(3-(2,5-dioctylphenyl)-thiophene) (PDOPT).
The techniques employed are absorption spectroscopy, current-voltage and complex
impedance spectroscopy measurements.
The absorption measurement reveals that the polymer, PDOPT, has an energy gap of about
2.02 eV and hence it belongs to the class of semiconducting materials. The I-V characteristic
of AVPDOPTIITO structure shows symmetrical but non-ohmic curves. The complex
impedance analysis exhibits a single semicircle whose diameter depends on the magnitude of
the applied voltage. For smaller values of the applied voltage, both for the reverse and forward
biases, the extrapolated diameter of the semicircle is larger. This value is consistent with the
result of the I-V measurements. So this device, AVPDOPTIITO, may be considered as a
metal-semiconductor device with no rectifying Schottky barrier formation at the AVPDOPT
interface. The small value of current may be due to high bulk resistance of the polymer, as
well as the probable formation of thick oxides of aluminium
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Keywords
Electrical Properties of Junctions between Aluminium