Regensburg 2019 – scientific programme

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DS: Fachverband Dünne Schichten

DS 3: Layer Properties: Electronic, Optical and Mechanical Properties

DS 3.8: Talk

Monday, April 1, 2019, 11:30–11:45, H39

Binding mechanism of fluorine-containing ketones on zinc oxide surfaces for thin film transistor passivation — •Jonas Köhling, Nataliya Kalinovich, Gerd-Volker Röschenthaler, and Veit Wagner — Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany

Solution processed metal-oxide thin film transistors are used in optical, mechanical and electrical applications. Oxygen and moisture induced surface traps cause instability and unreliability under electrical operation. For application purposes it is necessary to passivate surface traps. Tailored organic molecules can be effectively used for this task. For optimal functionality trap mechanisms and binding properties of these organic molecules have to be investigated.

In this work, the binding of fluorine-containing organic molecules on zinc oxide surfaces is monitored and the effect on electrical performance in thin film transistors was studied. Zinc oxide thin film transistors (12 nm thickness) were fabricated by aqueous spray pyrolysis. In order to overcome their instability against oxygen and moisture tailored organic fluorine-containing molecules with ketone groups as anchors sites were employed as passivation. Chemical binding of the molecules to hydroxide groups at the surface of zinc oxide is tracked by XPS and UV-Vis. The exact binding situation is elucidated by NMR. After passivation of the zinc oxide surface transistors exhibit almost vanished hysteresis, increased mobility and much better stability against electrical bias stress. Electrical results were correlated with the effective charge of the anchor atoms calculated by density functional theory.