Regensburg 2007 – wissenschaftliches Programm
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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.21: Poster
Dienstag, 27. März 2007, 18:00–20:00, Poster B
Improved sheet conductance in pentacene field-effect transistors using thiol and selenol modified electrodes — •Claudia Bock1, Duy Vu Pham1, Ulrich Kunze1, Daniel Käfer2, Gregor Witte2, and Christof Wöll2 — 1Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum — 2Physikalische Chemie I, Ruhr-Universität Bochum, D-44780 Bochum
In this work we demonstrate that a thiol and selenol treatment of the metal electrodes in bottom-contact pentacene field-effect transistors leads to an improved film homogeneity in the channel region, to a reduced trap-density and an improved sheet conductance. The devices consist of Ti/Au (1 nm/20 nm) electrodes prepared on an SiO2 dielectrics (d = 40 nm) which is thermally grown on a highly doped silicon substrate. The channel length was varied from L = 3 µm to L = 100 µm. The electrodes are modified by self-assembled monolayers of anthracene-2-thiol (AnT) and anthracene-2-selenol(AnS). Finally, a thin pentacene film is deposited in a molecular-beam deposition chamber (T = 65 ∘C). An untreated transistor acts as a reference sample. Two-terminal measurements for transistors with different channel length are used to separate the channel from the contact resistance. The contact resistance of the treated transistors are comparable to those of the reference sample, whereas the sheet-resistance of the channel is reduced up to one order of magnitude. The effecitve mobility µeff of the transistors treated in AnT (estimated from the linear region of the output characteristic) is corrected to µcor = 0.25 cm2/Vs by considering the contact resistance.