In-situ SHG microscopy investigation of the domain-wall-conductivity enhancement procedure in lithium niobate

Fuente: arXiv
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Autori principali: Kiseleva, Iuliia, Koppitz, Boris, Beyreuther, Elke, Roeper, Matthias, Seddon, Samuel D., Eng, Lukas M.
Natura: Preprint
Pubblicazione: 2025
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author Kiseleva, Iuliia
Koppitz, Boris
Beyreuther, Elke
Roeper, Matthias
Seddon, Samuel D.
Eng, Lukas M.
author_facet Kiseleva, Iuliia
Koppitz, Boris
Beyreuther, Elke
Roeper, Matthias
Seddon, Samuel D.
Eng, Lukas M.
contents Conductive domain walls (CDWs) in the uniaxial ferroelectric lithium niobate (LiNbO$_3$, LN) have attracted a lot of interest as potential elements in 2D nanoelectronics, due to their orders-of-magnitude larger electronic AC and DC conductivities as compared to the host material. On the way towards generating standardized CDWs into z-cut bulk LN crystals with controllable geometry and electrical properties, we have encountered setbacks recently: Although the first preparation step, i.e., the established UV-light-assisted liquid-electrode poling, reliably creates fully penetrating hexagonal domains with the DWs being aligned almost parallel to the polarization axis, the second step in the DW 'conductivity-enhancement' process through post-growth voltage ramping, resulted in randomly-shaped DWs as reflected in their different current-voltage (I-V) characteristics even after having applied the same process parameters. To clarify this phenomenon, we present here an \textit{in-situ} and time-resolved second-harmonic-generation (SHG) microscopy investigation of DW samples of different sizes, monitoring the DW evolution during that critical voltage ramping, which allowed us to reconstruct the 3D DW shapes both prior to and after the enhancement process. As a result, we are able to map the temporal changes of the local DW inclination angle $α$, and to quantify the DW velocity. As a consequence, we need to re-assess and re-think the origin of the DW conductivity (DWC) in LN: The hitherto assumed simple connection between $α$ and the DWC can not be generalized, since point defects accumulating along DWs act as extra sources for charge carrier trapping/release, significantly contributing to the DW current.
format Preprint
id arxiv_https___arxiv_org_abs_2507_07466
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle In-situ SHG microscopy investigation of the domain-wall-conductivity enhancement procedure in lithium niobate
Kiseleva, Iuliia
Koppitz, Boris
Beyreuther, Elke
Roeper, Matthias
Seddon, Samuel D.
Eng, Lukas M.
Materials Science
Conductive domain walls (CDWs) in the uniaxial ferroelectric lithium niobate (LiNbO$_3$, LN) have attracted a lot of interest as potential elements in 2D nanoelectronics, due to their orders-of-magnitude larger electronic AC and DC conductivities as compared to the host material. On the way towards generating standardized CDWs into z-cut bulk LN crystals with controllable geometry and electrical properties, we have encountered setbacks recently: Although the first preparation step, i.e., the established UV-light-assisted liquid-electrode poling, reliably creates fully penetrating hexagonal domains with the DWs being aligned almost parallel to the polarization axis, the second step in the DW 'conductivity-enhancement' process through post-growth voltage ramping, resulted in randomly-shaped DWs as reflected in their different current-voltage (I-V) characteristics even after having applied the same process parameters. To clarify this phenomenon, we present here an \textit{in-situ} and time-resolved second-harmonic-generation (SHG) microscopy investigation of DW samples of different sizes, monitoring the DW evolution during that critical voltage ramping, which allowed us to reconstruct the 3D DW shapes both prior to and after the enhancement process. As a result, we are able to map the temporal changes of the local DW inclination angle $α$, and to quantify the DW velocity. As a consequence, we need to re-assess and re-think the origin of the DW conductivity (DWC) in LN: The hitherto assumed simple connection between $α$ and the DWC can not be generalized, since point defects accumulating along DWs act as extra sources for charge carrier trapping/release, significantly contributing to the DW current.
title In-situ SHG microscopy investigation of the domain-wall-conductivity enhancement procedure in lithium niobate
topic Materials Science
url https://arxiv.org/abs/2507.07466