Dresden 2011 – scientific programme

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DS: Fachverband Dünne Schichten

DS 63: Organic Thin Films II

DS 63.2: Talk

Friday, March 18, 2011, 12:15–12:30, GER 38

Trapping analysis of polythiophene based field-effect transistors with modified gate oxide — •Steve Pittner and Veit Wagner — School of Engineering, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany

Organic semiconductors have proven to be suitable materials for electronic devices like organic field effect ransistors (OFET). But their charge mobility, an important parameter for technical applications, is very sensitive to the semiconductor-insulator interface, especially to unintended interface states.

We have investigated the influence of different interface state concentrations on the charge transport at the silicon oxide / poly(3-hexylthiophene) (P3HT) interface. Different surface treatments were applied to the silicon oxide layer covering a highly doped silicon wafer to modify the density of surface states. On this surface the P3HT was deposited. The carrier density in the P3HT was determined optically by charge modulation spectroscopy (CMS). This allows to map the carrier concentration spatially and energetically next to the electrodes. Parallel analysis by Impedance spectroscopy allowed to determine the doping profile of the whole semiconductor layer via analysis of the change of the depletion capacitance. This analysis allowed to correlate residual carrier density with high doping concentration close to the interface.