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HL: Halbleiterphysik
HL 6: Optische Eigenschaften
HL 6.5: Vortrag
Montag, 26. März 2001, 11:30–11:45, S9/10
Optical Anisotropy of Organic Layers Grown on GaAs(100) — •A.M. Paraian1, U. Rossow2, S. Park1, M. Friedrich1, T.U. Kampen1, and D.R.T. Zahn1 — 1Institut für Physik, TU Chemnitz, 09107 Chemnitz, Germany — 2Institut für Technische Physik, TU Braunschweig, Mendelssohnstr. 2, 38106 Braunschweig, Germany
The application of reflectance-difference/anisotropy-spectroscopy (RDS/RAS) and spectroscopic ellipsometry for the characterization of organic layers will be discussed and results for 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) grown on sulfur passivated GaAs(100) surfaces are presented.
The RDS/RAS spectra for PTCDA layers were taken in situ at room temperature. Spectral features related to GaAs and PTCDA are observed. For GaAs the bulk is optically isotropic and the RDS/RAS signal originates at surfaces, which have reduced symmetry. The PTCDA films have a polycrystalline structure with a monoclinic symmetry. Spectral features due to HOMO-LUMO transitions of PTCDA are observed, while the GaAs features are induced by the reduced symmetry of the interface.
The features attributed to HOMO-LUMO transitions also are very well resolved in the ellipsometric spectra covering the visible and near UV range. The imaginary part of the pseudo-dielectric function varies as a function of the angle of incident light and the azimuthal sample orientation.