Berlin 2008 – wissenschaftliches Programm

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 3: Organic Devices I

SYSA 3.3: Vortrag

Dienstag, 26. Februar 2008, 15:15–15:30, H 2013

Peculiarities of OFET performance due to hopping transport near the gate insulator interface — •Susanne Scheinert¹ and Gernot Paasch² — ¹TU Ilmenau — ²IFW Dresden

The operation of thin film field-effect transistors is determined by the channel at the interface to the gate oxide. There the carrier concentration can be changed from depletion to accumulation and the electric field increases from source to drain. For variable range hopping in disordered organic semiconductors as the active layer, the mobility depends on both the carrier concentration and the field. Our numerical simulation study shows that besides the known dependency of the field-effect mobility on the gate voltage there occur in addition (i) a strong modification of the saturation current, (ii) a shift of the threshold voltage, and (iii) an increase of the inverse threshold slope. In addition, (iv) the influence of the dependency on the mobility is critically determined by the transistor channel length. The origin of all these peculiarities is clarified by analyzing the internal profiles of concentrations and fields. Conclusions are drawn on the possibilities of parameter extraction from measured current characteristics.