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HL: Halbleiterphysik

HL 25: Organische Halbleiter II

HL 25.11: Talk

Tuesday, March 25, 2003, 17:45–18:00, BEY/81

Raman Monitoring of In and Ag Growth on PTCDA and DiMe-PTCDI Thin Films — •Beynor A. Paez, G. Salvan, S. Silaghi, T.U. Kampen, and D.R.T. Zahn — Insitut für Physik, Technische Universität Chemnitz, D-09107, Germany

Formation of In and Ag interfaces on 3,4,9,10- perylene-tetracarboxylic dianhydride (PTCDA) and dimethylperylene 3,4,9,10-dicarboximide (DiMe-PTCDI), were investigated in situ by means of Raman spectroscopy. A significant enhancement of internal vibrational modes is observed in all cases, clearly indicating the presence of surface enhanced Raman scattering. The molecules having direct contact with the metal are involved in a weak ground state dynamical charge transfer, resulting in a breakdown of selection rules. This contradicts previous models of covalent bond formation between In and O atoms in PTCDA [1]. The Raman scattering of molecules away form metal interface is enhanced via dipole plasmon resonances. This indicates a high roughness of the metallic film. The enhancement factors can be used to extract information on interdiffusion and morphology of the metal film.

[1] Satoshi Kera, Hiroyuki Setoyama, Miki Onoue, Koji K. Okudaira, Yoshiya Harada, and Nobuo Ueno. Phys. Rev. B 63, 115204 (2001)