IFW-Dresden, Helmholtzstr. 20, 01069 Dresden, Germany.
Nanoscale. 2017 Aug 3;9(30):10933-10939. doi: 10.1039/c7nr00217c.
Conducting domain walls (CDWs) in ferroelectric materials are promising candidates for applications in a manifold of nanoscale, optoelectronic devices. Characterization of their microscopic properties, however, remains challenging due to their small dimension and highly insulating environment. Here, we inspect individual CDWs in single-crystalline LiNbO by the combination of photoemission electron microscopy (PEEM) and second harmonic generation (SHG) microscopy. While SHG unveils the overall domain wall inclination angle α, PEEM is sensitive to local conductance variations, both at and away from the domain wall. Thus, the two imaging techniques deliver complementary information over a large field of view. In agreement with earlier theoretical predictions we find that the local conductance is dictated by α and reveal a quantitative connection between them. Our results help to elucidate the electronic structure of CDWs and underline the value of PEEM as a non-contact characterization tool for mapping local conductance variations in highly resistive environments.
铁电材料中的导带壁（CDWs）是在多种纳米、光电设备中应用的有前途的候选材料。然而，由于其小尺寸和高绝缘环境，对其微观特性的表征仍然具有挑战性。在这里，我们通过光电发射电子显微镜（PEEM）和二次谐波产生（SHG）显微镜的组合，检查了单晶 LiNbO 中的单个 CDW。虽然 SHG 揭示了整个畴壁倾斜角α，但 PEEM 对畴壁处和远离畴壁的局部电导变化都很敏感。因此，这两种成像技术在很大的视场中提供互补的信息。根据早期的理论预测，我们发现局部电导率由α决定，并揭示了它们之间的定量关系。我们的结果有助于阐明 CDW 的电子结构，并强调了 PEEM 作为在高电阻环境中映射局部电导变化的非接触特性化工具的价值。
