Berlin 2005 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 23: Postersitzung I
DS 23.42: Poster
Freitag, 4. März 2005, 16:00–18:30, Poster TU B
Growth mode analysis of thiophene based OFETs by atomic force microscopy — •T. Muck, J. Fritz, and V. Wagner — School of Engineering and Science, International University Bremen, D-28759 Bremen, Germany
Charge transport in organic field-effect transistors takes place at the
organic/insulator interface. Thereby, only the first monolayers of the
organic molecules have been found to be important for the device
performance. Properties like growth mode, number and size of grains
influence the transport behavior. Furthermore, optimized growth
conditions are modified by the presence of source and drain electrodes
in bottom configuration.
In this study we analyzed the growth of the thiophene derivatives
dihexylquaterthiophene (DH4T) and dihexylsexithiophene (DH6T) on
SiO2/Si-transistor templates with gold electrodes in bottom
configuration by atomic force microscopy (AFM). The organic films were
deposited by organic molecular beam deposition (OMBD) in ultra high
vacuum. Film thickness gradients from sub-monolayer to several
monolayers were produced on the same sample via a motor driven shutter.
At elevated substrate temperatures a layer-by-layer growth was observed.
We found, that in the region close to the gold contacts the organic
molecules do not form an homogenous film due to a transport of molecules
from the channel region towards the electrodes. Furthermore, on gold we
observe upright standing molecules which implies an additional
structural disturbance at the channel/electrode interface.