Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 19: Organische Halbleiter I
HL 19.4: Vortrag
Dienstag, 25. März 2003, 11:45–12:00, BEY/81
Surface charge carrier mobility in organic single crystals — •Bruno Gompf1, Andreas Schön1, Norbert Karl2, and Martin Dressel1 — 11.Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 705550 Stuttgart — 23.Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 705550 Stuttgart
Electronic transport in organic thin films is usually limited by grain boundaries, imperfections and traps. To learn more about the intrinsic properties of organic semiconductors it is necessary to use good single crystals. Space Charge Limited Current measurements (SCLC) are a powerful tool for the characterization of wide band gap materials and were widely used for the determination of bulk mobilities and bulk trap concentrations in organic semiconductors. But for electronic devices the surface is as important as the bulk. SCLC measurements in surface electrode geometry allow us to investigate the mobility parallel to and the trap concentratuion close to the surface. On well-prepared surfaces of highly purified perylene single crystals we found SCLC mobilities and trap concentrations that compare well to the bulk values obtained from time-of-flight measurements. Therefore these organic surfaces appear to have no additional surface states or traps. The influences of different growth methods and of the preparation conditions, such as as annealing (in argon or hydrogen), or polishing, on the quality of the crystal surface will be analysed.