Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 25: Organische Halbleiter II
HL 25.13: Vortrag
Dienstag, 25. März 2003, 18:15–18:30, BEY/81
Study of DiMe-PTCDI molecular orientation on S-GaAs(100) by NEXAFS spectroscopy — •Henry Mendez1, G. Gavrila1, J. Wells2, D.V. Vyalikh3, T.U. Kampen1, W. Braun4, and D.R.T. Zahn1 — 1Institut für Physik, Technische Universität Chemnitz, D-09107, Chemnitz, Germany — 2Trinity College, Dublin, Ireland — 3Russian-German Laboratory at BESSY II, D-12489 Berlin-Adlershof, Germany — 4BESSY GmbH, Albert-Einstein-Strasse 15, D-12489 Berlin-Adlershof, Germany
Dimethyl-3,4,9,10-perylenetetracarboxylic diimide (DiMe-PTCDI) is used for the modification of metal/inorganic semiconductor interfaces. Compared to the extensively studied organic molecule PTCDA, the molecular structure of DiMe-PTCDI differs in the presence of two CH3 groups bonded to nitrogen atoms at both ends of the perylene core. It has been repeatedly reported that this molecule grows coplanar to the substrate surface. From infrared and Raman studies carried out for both organic compounds, it has been found that the tiny difference in molecular structure has a quite pronounced effect on molecular ordering. The purpose of this study is to determine the molecular orientation by simultaneously depositing DiMe-PTCDI on two different oriented S-GaAs(100) substrates. The difference between the substrates corresponds to an in-plane rotation of the substrate by 90o. Angular dependent NEXAFS spectra in the C K-edge region were performed for 10nm thick DiMe-PTCDI layer grown on both substrates in RGBL beamline at BESSY II. The results show that the molecular plane of DiMe-PTCDI lies almost perpendicular respect to the 2x1 reconstructed surface of S-GaAs.