Berlin 2005 – wissenschaftliches Programm

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SYOO: Organic Optoelectronics and Photonics

SYOO 1: Organic Field-Effect Transistors

SYOO 1.1: Vortrag

Montag, 7. März 2005, 09:45–10:00, TU C130

A pentacene ambipolar transistor: experiment and theory — •Roland Schmechel, Marcus Ahles, and Heinz von Seggern — TU-Darmstadt, Institut für Materialwissenschaft, Petersenstr. 23, D-64287 Darmstadt, (Germany)

A pentacene ambipolar transistor with top-gold and top-calcium contacts is realized by utilizing a parallactic effect of the shadow mask during vapor deposition. The pentacene has been deposited on top of a silicon dioxide gate-insulator, while the pentace/SiO2 interface has been Ca-doped to compensate electron traps. An equivalent circuit model based on a resistor-capacitor network is used to describe the basic electrical properties of the transistor. Shockley-like analytical expressions for the output and transfer characteristics as well as analytical expressions for the potential and charge distributions in the channel are derived under the assumption of a high electron - hole recombination probability. The model is fitted to the experimental results and yields comparable hole and electron mobilities, both in the order of 0.1 cm²/Vs. The increasing threshold voltages with increasing gate voltages are discussed as an indication for an increasing amount of captured charge carriers in the channel.