Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 70: Devices II

HL 70.4: Vortrag

Mittwoch, 28. März 2012, 18:00–18:15, EW 015

Electrical characterization of C60 molecules embedded in a MOS diode — •Daniel Beckmeier and Hermann Baumgärtner — Universität der Bundeswehr München

Fullerene (C60) molecules were embedded in a SiO2 layer. Around this layer a MOS diode structure was defined to study the charge and discharge of the electronic states caused by the molecules. This structure was formed by evaporating a submonolayer of C60 molecules onto a clean silicon wafer followed by an in situ overgrowth of the molecules with amorphous silicon inside the same UHV system. These samples were then oxidized in a wet atmosphere to achieve a complete encapsulation of the C60 molecules by the thermal oxide without destroying the molecules. Aluminum contacts were defined on these layers to perform capacitance voltage (CV), current voltage (IV) and electrical stress measurements on the diodes. CV measurements showed a shift of the flatband voltage caused by the injected charge carriers. This shift was reversible for small voltages of opposite signs. The IV measurements showed a Fowler-Nordheim tunneling current for diodes without and with C60. For samples with C60 the electron current injected from the silicon into the oxide started at smaller fields and had a smaller slope compared to the metal electrode-injected current. We propose a model including trap assisted current injection to explain this behavior.