Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 9: Poster 1
HL 9.93: Poster
Montag, 23. März 2009, 14:30–17:00, P2
Switching of drain potential in organic field effect transistor — •Ingo Hörselmann and Susanne Scheinert — TU Ilmenau
An organic field effect transistor (OFET) with source/drain electrodes self-aligned to bottom gate contact was prepared, resulting in a low overlap capacitance CGD of 10pF for a channel width to length ratio of 8000. The gate insulator is a 200nm Si3N4 layer grown by chemical vapor deposition (CVD). As active semiconductor material poly(3-hexylthiophene) (P3HT) was used to produce a p-channel transistor. The drain and gate potential was switched with square-wave pulses and the transient response of the source and drain currents was recorded to investigate the transient behavior. Switching the drain potential between 0 and -10V with a ramptime of 50µs at constant gate-source voltage, which deplets the semiconductor layer, the measured transient source current is 5 orders higher then the expected displacement current originating from the geometry capacitance between source and drain. Numerical 2D simulation affirmed this tendency in case of acceptor-like bulk trap densities of about 5 × 1017cm−3. The simulated decay behavior for switching the drain potential from -10 to 0V showed a strong dependency on the energy of the trap level, which is supported by an observed current decay during the measurements.