Dresden 2003 – wissenschaftliches Programm
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DF: Dielektrische Festkörper
DF 7: Poster
DF 7.16: Poster
Mittwoch, 26. März 2003, 14:30–18:00, P2a
Optimization of r.f. magnetron sputtered alumina films for gate insulators in organic field effect transistors — •Michael Voigt1, Moritz Sokolowski1, Lioudmila Knoth2, Andrea Schmid2, Marcel Schneider2, and Eberhard Umbach2 — 1Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstr. 12, D-53115 Bonn — 2Experimentelle Physik II,Universität Würzburg, Am Hubland, D-97074 Würzburg
Thin films (d = 160 nm) of alumina were prepared on ITO at 300 K by r.f. magnetron sputtering from an Al2 O3 ceramic target in pure Ar (pAr = 8 · 10−3 mbar) or in Ar and O2 mixtures. Contacts (area = 6 mm2) were made by evaporation of Au onto the top sides. The aim was to achieve good dielectric films for gate insulators in organic field effect transistors.
The breakdown fields Eb (measured at 10−6 mbar; j < 10−7 A/cm2) depend remarkably on the partial pressure of O2 in the sputter plasma and on the history of the Al2 O3 target. By varying the partial pressure of O2, we found the highest Eb (0.7 MV/cm) at 1% O2. Even higher Eb of 1.2 MV/cm were observed, if the Al2 O3 target was first conditioned by sputtering 30 min in a mixture of Ar + O2 (1:1) and subsequent sputtering of the film in pure argon.
Atomic force microscopy studies show that the surfaces of these films are relatively rough and show typical grain sizes of 0.3-0.5 µm.
This work is supported by the DFG, through the research project "Organic Field Effect TransistorsNo-dq.