R2D2 -- An equivalent-circuit model that quantitatively describes domain wall conductivity in ferroelectric LiNbO${}_3$

Abstract

Ferroelectric domain wall (DW) conductivity (DWC) can be attributed to two separate mechanisms: (a) the injection/ejection of charge carriers across the Schottky barrier formed at the (metal-) electrode-DW junction and (b) the transport of those charge carriers along the DW. Current-voltage (IU) characteristics, recorded at variable temperatures from LiNbO${}_3$ (LNO) DWs, are clearly able to differentiate between these two contributions. Practically, they allow us here to directly quantify the physical parameters relevant for the two mechanisms (a) and (b) mentioned above. These are, e.g., the resistance of the DW, the saturation current, the ideality factor, and the Schottky barrier height of the electrode/DW junction. Furthermore, the activation energies needed to initiate the thermally-activated electronic transport along the DWs, can be extracted. In addition, we show that electronic transport along LiNbO${}_3$ DWs can be elegantly viewed and interpreted in an adapted semiconductor picture based on a double-diode/double-resistor equivalent circuit model, the R2D2 model. Finally, our R2D2 model was checked for its universality by fitting the DWC data not only to z-cut LNO bulk DWs, but equally to z-cut thin-film LNO DWs, and DWC from x-cut DWs as reported in literature.

arXiv comment10 pages, 7 figures; with included supporting information (6 pages, 4 figures)

References in corpus (3)

• Static conductivity of charged domain wall in uniaxial ferroelectric-semiconductors
• Ultra-High Carrier Mobilities in Ferroelectric Domain Wall Corbino Cones at Room Temperature
• Hall mobilities and sheet carrier densities in a single LiNbO${}_3$ conductive ferroelectric domain wall

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• Demonstration of domain wall current in MgO-doped lithium niobate single crystals up to 400 °C
• In-situ SHG microscopy investigation of the domain-wall-conductivity enhancement procedure in lithium niobate
• Dynamics of Conducting Ferroelectric Domain Walls
• The domain-wall/metal-electrode injection barrier in lithium niobate: Which electrical transport model fits best?