Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 39: Oxide und Isolatoren II

O 39.3: Vortrag

Freitag, 28. März 2003, 11:45–12:00, FOE/ORG

Investigating the Local Electrical Conductivity of Polycrystalline BaTiO₃ with Conductive AFM — •A. Kindlein, H. Neddermeyer, H.-Th. Langhammer, and K.-M. Schindler — Martin-Luther-Universität Halle-Wittenberg, FB Physik, D-06099 Halle

In order to understand the electrical properties of polycrystalline BaTiO₃ samples it is necessary to investigate local differences in the electrical conductivity in the nanometer range. For this purpose we used an atomic force microscope with a conductive tip in contact mode and simultaneously recorded topography and conductivity maps by applying a voltage between tip and sample and measuring the tip current. The character of the conductivity was further investigated by I-U spectroscopy. As a result of changes in the contact area between tip and sample, surfaces terraces and facets of individual grains are imaged. In addition, distinct areas of extremely low conductivity are found, which were assigned to Ti rich phases. In addition to topography related contrasts on single grains, the conductivity maps of polished samples show major differences between grains. On La-doped ceramics the ferroelectric domains could be imaged, which wasn’t possible using other methods. Finally, we found that repeated imaging of an area leads to a long lasting (> 48 h) reduction in conductivity. I-U spectroscopy shows that these conductivity changes are not reversible by applying an inverse voltage. The utilisation of this effect as a write-once process will be discussed.