Regensburg 2002 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 38: Poster 2

HL 38.62: Poster

Donnerstag, 14. März 2002, 16:30–19:00, Poster A

Electronic properties of oxygen exposed 3,4,9,10-perylene-tetracarboxylic dianhydride surfaces — •Gianina Nicoleta Gavrila, Thorsten Ü Kampen, and Dietrich R.T. Zahn — Insitut für Physik,Technische Universität Chemnitz,D-09107

Thin films of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) can be used to decrease the barrier heights of Ag/GaAs(100) from 0.81 eV to 0.64 eV by changing the thickness of the PTCDA interlayer between 0   60 nm [1]. Exposure of Ag/PTCDA/GaAs(100) contacts to oxygen results in an increase in barrier height to a value larger than the one of a bare Ag/GaAs(100) Schottky contact. This behaviour is attributed to an oxygen induced shift of the Fermi level from its original position of 2 eV above the highest occupied molecular orbital towards the middle of the band gap of PTCDA [2]. This effect is investigated in detail by exposing thin films of PTCDA grown on GaAs(100) to oxygen. Ultraviolet photoemission spectroscopy is used to determine changes in the ionisation energy, while changes in the work function are followed with a Kelvin probe. [1] T. U. Kampen, S. Park, and D. R. T. Zahn, Appl. Surf. Sci., in print. [2] T. U. Kampen, S. Park, and D. R. T. Zahn, submitted to J. Vac. Sci