Berlin 2015 – scientific programme

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DS: Fachverband Dünne Schichten

DS 36: Poster Session I

DS 36.87: Poster

Thursday, March 19, 2015, 09:30–12:00, Poster A

A Novel Concept of an Oxide Thin Film Sensor for Integrated Filtering and Local Signal Detection — •Aleksandr Markov, Eugen Hollmann, and Roger Wördenweber — Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428, Jülich

Engineering of a frequency dependence of permittivity can be of interest for various sensor application. In this work a strong modification of the frequency dependence of ferroelectric properties is achieved via a controlled deposition process of the metal electrode (Pt) into the ferroelectric layer ((Ba,Sr)TiO3). For this purpose a series of Ba0.5Sr0.5TiO3 layers has been deposited onto Pt coated sapphire at various temperatures range from 660 °C to 760 °C. Additionally a top electrode is deposited at room temperature. The electronic properties of the capacitors are investigated via frequency dependent cryoelectronic measurements, structure and stoichiometry are analyzed via X-ray and RBS measurements, respectively. The analysis of the permittivity and tangent loss show a strong frequency dependence of the permittivity in a small region of the deposition temperatures (680 °C - 710 °C), i.e. the permittivity changes from εeff of 600 at low frequency to εeff of 20 at high frequency. This behavior is caused by a partial diffusion of Pt into the ferroelectric layer and can be explained by the Maxwell-Wagner model. The diffusion is supported by RBS data obtained for the samples deposited at different temperatures. Potential application of these layers for sensors with integrated filtering are sketched.