Berlin 2008 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 11: Dielectric and ferroelectric thin films and nanostructures I

DF 11.5: Vortrag

Mittwoch, 27. Februar 2008, 15:20–15:40, EB 107

Electron emission from ferroelectric thin films induced by polarization switching — •Oliver Mieth¹, Hannes Klumbies¹, Günter Milde², Gerald Gerlach², and Lukas Eng¹ — ¹Institut für Angewandte Physik, Technische Universität Dresden — ²Institut für Festkörperelektronik, Technische Universität Dresden

Ferroic materials are promising candidates for high-efficient electron emission in various applications. However, most work in this research field so far did focus on electron emission from bulk ferroelectric materials.

Here we present studies on electron emission under ultra-high vacuum conditions (base pressure < 10⁻⁹ mbar) using PZT and other thin ferroelectric films as the emitter source that measure some hundred nanometer in thickness. Electron emission is collected through 10 - 20 µm-sized apertures lithographically manufactured into the top electrode. We show that current densities of up to 10⁻¹¹ A/cm² are measurable by simply switching the thin film in the 10 Volt regime. The count rates measured as a function of applied switching voltage showed an almost linear behavior, in contrast to bulk PMN-PT single crystals which exhibited an exponential relationship. For correlating these results to known ferroelectric properties, e.g., coercive field and local imprint effects, local hysteresis loops were recorded simultaneously using Piezoresponse Force Microscopy. We are able to demonstrate that polarization switching induces the onset of electron emission. These experimental findings were consistently interpreted using Finite Element Method (FEM) modeling of the investigated structure.