LOW VOLTAGE OFETS AND MIS DIODES UTILIZING ANODIZED ALUMINIUM OXIDE
K. Koren, K. Schmoltner, J. Kofler, A. Klug and E. J. W. List
NanoTecCenter Weiz Forschungsgesellschaft mbH, Weiz, Austria & Institute of Solid State Physics, Graz University of Technology, Austria
15:20 - 17:30 Thursday 24 October 2013 Foyer Alte Technik Organic field-effect transistors (OFETs) are highly promising candidates for chemical and biological sensing. Many organic compounds are solution-processable at low temperatures on a variety of substrates, which allows for cost-effective fabrication methods, leading to smart (disposable) sensor tags. Moreover, organic (semiconducting) materials can be tailored with respect to their chemical and physical properties, enhancing the sensitivity and selectivity towards a specific analyte. Concerning the detection of ions in aqueous solutions, a water-stable operation of OFET sensor elements is crucial. Thus low-voltage operation is a prerequisite.
In this context, we investigate OFETs with reduced operating voltages by utilizing a thin high-k dielectric gate insulator. In particular, anodized aluminium oxide Al2O3 was studied thoroughly in capacitor structures, metal-insulator-semiconductor (MIS) diodes as well as bottom-gate OFETs. These different architectures were used to compare bulk and interface properties of the constituting materials in detail. Low-voltage poly(3-hexylthiophene) (P3HT)-based top- and bottom-contact OFETs were investigated in terms of operational stability, field-effect mobility, switch-on voltages and on/off-current ratios. Moreover, information about doping, trapping processes and mobile charges were obtained by characterizing MIS diodes.
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