Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 61: Organische Halbleiter

HL 61.5: Vortrag

Mittwoch, 9. März 2005, 11:45–12:00, TU P270

Electronic Properties of a Metal/Organic/GaAs Heteroestructure — •Henry Méndez, Ilja Thurzo, Mihaela Gorgoi, Cristian Iacovita, Gianina Gavrila, and Dietrich R.T. Zahn — Institut für Physik, Reihenheiner Str.70 D-09107 Chemnitz, Germany

Devices based on a metal/organic/GaAs heterostructure were prepared under UHV conditions and their electrical properties studied in situ. Hydrogen plasma treated GaAs(100) (H⁺GaAs) and the perylene derivative dimethyl-3,4,9,10-perylenetetracarboxylic diimide (DiMe-PTCDI) were used as inorganic substrate and organic material, respectively. Silver contacts were then deposited through a shadow mask. The electronic transport properties were investigated by UPS, IV, CV and QTS techniques. A barrier height of (0.83 ± 0.05) eV for the reference Ag/H⁺GaAs diode was deduced from IV characteristics. Organic modification of the reference diode with DiMe-PTCDI leads to a decrease in the effective barrier height with increasing thickness of the molecular film. The electrical measurements show that at the interface LUMO of DiMe-PTCDI lies below the CBM of GaAs(100). This is confirmed by IPES measurements on a DiMe-PTCDI layer deposited on H⁺GaAs. The transport mechanism through the device is discussed considering the Fermi level alignment at the organic/inorganic interface and the role of interfacial and bulk trap levels. All the information is taken into account when simulating IV characteristics of the organic modified device.