Regensburg 2002 – wissenschaftliches Programm

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SYOH: Organische Halbleiter

SYOH 3: Organic Field-Effect Transistors

SYOH 3.3: Vortrag

Montag, 11. März 2002, 12:30–12:45, H37

Dynamic measurements on organic field-effect transistors — •Torsten Finnberg, Roland Schmechel, and Heinz von Seggern — TU Darmstadt, Petersenstrasse 23, 64287 Darmstadt

The cut-off-frequency or its equivalent the pulse answer is one of the most important factors determining the practical applicability of organic field-effect transistors since it establishes the maximum switching frequency of the transistor. Considering this, transient pulse measurements were performed on organic thin-film transistors. The organic layers were deposited on lithographically defined gold-contacts on SiO₂ functioning as gate oxide and highly doped Si as gate contact. The active layer consists of the organic semiconductor pentacene which is being deposited by PVD in vacuum. The variation of the drain current during the application of voltage pulses on the gate-source contact while keeping the drain-source voltage constant were measured. Further reports are given on experiments concerning double pulses with variable delay time and at different temperatures and illumination. The results are discussed in reference towards the dynamics and charge transport of the accumulation zone. A current decaying with time after switching the transitor off is connected to localised charge carriers and the dependence of the decay time on the wavelength and intensity of the light and the temperature is being discussed. A simple model for estimating the trap density is presented.