Dresden 2011 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 16: Dielectric surfaces and interfaces

DF 16.3: Vortrag

Donnerstag, 17. März 2011, 14:55–15:15, MÜL Elch

UV-induced domain wall conductivity at room temperature in Mg-doped lithium niobate single crystals — •Mathias Schröder, Alexander Haußmann, and Lukas M. Eng — Institute of Applied Photophysics, Technische Universität Dresden, D-01062 Dresden, Germany

Ferroelectric 180° domain walls (DWs) may play an important role in future electronic devices. The size and position of domains and DWs can be easily controlled. In addition, DWs in lithium niobate (LiNbO3: LNO) can be functionalized through depositing metallic and/or molecular nanowires by means of ferroelectric lithography [1,2]. Moreover, the same DWs become conductive under super-bandgap illumination, hence manifesting switchable, tunable, and nanoscale conductive channels that extend across the whole insulating bulk material. However, a detailed understanding of the underlying processes that lead to DW conductivity is still missing to date. Here, we report on conductive-AFM (c-AFM) measurements on 5 mol% Mg-doped congruent LNO single crystals. We compare the c-AFM results with the domain distribution recorded by piezoresponse force microscopy (PFM). Surprisingly, we find an enhanced current flow inside the 180° DWs under super-bandgap UV-illumination even at ambient conditions. The DW conductivity was studied as a function of wavelength, light intensity and doping concentration. Our results suggest a hopping transport being relevant for the reported DW conductivity.

[1] S.V. Kalinin, et al., Nano Lett. 2, 589 (2002).

[2] A. Haussmann et al., Nano Lett. 9, 763 (2009).