Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 13: Electronic structure II

O 13.5: Talk

Monday, March 23, 2009, 16:00–16:15, SCH A216

Engeneering the band line up of Si(111) and organic semiconductors by -CH3, -H and -GaSe termination — •Thomas Mayer¹, Ralf Hunger², Andreas Klein¹, and Wolfram Jaegermann¹ — ¹TU-Darmstadt Fachbereich Materialwissenschaften — ²now Solibro GmbH Thalheim

We report on the variation of the Si(111) ionization energy induced by surface dipoles of -CH3, -H, and -GaSe terminations. Photoelectron spectroscopy is used to determine the experimental dipoles which are compared to model calculations applying simple geometric and electronegativity arguments. The position of the vacuum level within bulk Si is derived to be 5.12 eV above the valence band maximum. In addition the variation of the band line up of Si(111) towards PTCDA and ZnPc is measured. While for -CH3 and -H terminations the Anderson model applies, for GaSe termination an additional interface dipole is induced. We relate this dipole to a varied molecule orientation.