Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 50: Poster II
HL 50.38: Poster
Donnerstag, 30. März 2006, 16:30–19:00, P3
Ellipsometry on pentacene thin films OFETs. — •Daniel Faltermeier1, Bruno Gompf1, Matthias Fischer1, Ashutosh Tripathi2, Jens Pflaum2, and Martin Dressel1 — 11. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart — 23. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart
Pentacene with its high effective carrier mobility is one of the most promising organic semiconductors, and much work has been done in characterizing the electronic properties of thin pentacene films. Despite these efforts the correlation between morphology and function is still not well understood. We present a systematic approach by spectroscopic ellipsometry on highly purified pentacene thin films, evaporated on silicon wafers with thermal SiO2 in the temperature range between 5 K and 350 K. There a temperature dependent shift of the optical spectra can be observed. The optical data are correlated with x-ray diffraction, atomic force microscopy and field effect measurements performed at room temperature at the same films. By tuning the evaporation parameters like substrate temperature and evaporation rate one can clearly correlate changes in the ellipsometric spectra, especially the influence of the mid-gap states acting effectively as charge-carrier traps, with mobilities extracted from I-V curves. We also compare the thin-film results with spectroscopic ellipsometry measurements obtained on pentacene single crystals, to learn more about the intrinsic properties of the material.