Regensburg 2004 – scientific programme

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.68: Poster

Thursday, March 11, 2004, 18:00–21:00, B

Morphology-performance relationship in pentacene-based thin film transistors — •Wolfgang Kalb¹, Philippe Lang², Mohammad Motaghi², Matthias Wuttig¹, and Gilles Horowitz² — ¹1. Physikalisches Institut der RWTH Aachen, Germany — ²ITODYS / Universite Paris 7, France

Pentacene-based thin film transistors were fabricated on Si/alumina substrates with gold top-contact source and drain electrodes. On some devices, the alumina surface was modified with fatty acid self-assembled monolayers prior to pentacene deposition. Pentacene layers were grown by vacuum evaporation at various deposition rates ranging from 0.003A/s to 3A/s and various film thicknesses. The gate voltage dependent mobility was extracted from the transfer characteristics with correction for contact resistance. We find that treating the alumina with fatty acid leads to a substancial increase in the mobility. The mobility furthermore depends upon the film thickness. An intermediate deposition rate of 0.1A/s is found to lead to optimal transistor performance. The growth mechanism of the pentacene layers was followed by atomic force microscopy. It is found that the primary growth-stage of pentacene-films leading to transistors of best performance is characterised by a high nucleation rate. The size of the grains tends to drastically increase during the deposition process.