Kramer Thilo, Mierwaldt Daniel, Scherff Malte, Kanbach Mike, Jooss Christian
Institute of Material Physics, University of Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen, Germany .
Institute of Material Physics, University of Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen, Germany.
Ultramicroscopy. 2018 Jan;184(Pt A):61-70. doi: 10.1016/j.ultramic.2017.08.012. Epub 2017 Aug 23.
Non-volatile resistance change under electric stimulation in many metal-oxides is a promising path to next generation memory devices. However, the underlying mechanisms are still not fully understood. In situ transmission electron microscopy experiments provide a powerful tool to elucidate these mechanisms. In this contribution, we demonstrate a TEM lamella geometry for in situ biasing with two fixed electrode contacts ensuring low and stable contact resistances. We use PrCaMnO sandwiched by Pt electrodes as model system. The evolution of manganese valence state during electric stimulation in different environments is mapped by means of electron energy loss spectroscopy with high spatial resolution in STEM. Correlation of Mn valence with local oxygen content is found. In addition to electrically driven switching, beam-induced redox reactions in oxygen environment are observed. This effect might be restricted to thin lamellae. In general, our results support that bulk oxygen electromigration is the relevant mechanism for non-volatile resistive switching in PCMO.
许多金属氧化物在电刺激下的非易失性电阻变化是通往下一代存储器件的一条充满前景的途径。然而，其潜在机制仍未被完全理解。原位透射电子显微镜实验为阐明这些机制提供了一个强大的工具。在本论文中，我们展示了一种用于原位偏置的TEM薄片几何结构，其具有两个固定电极触点，可确保低且稳定的接触电阻。我们使用夹在Pt电极之间的PrCaMnO作为模型系统。通过在扫描透射电子显微镜（STEM）中具有高空间分辨率的电子能量损失谱，绘制了在不同环境下电刺激过程中锰价态的演变。发现了锰价与局部氧含量之间的相关性。除了电驱动的开关效应外，还观察到了在氧环境中的束诱导氧化还原反应。这种效应可能仅限于薄片。总体而言，我们的结果支持体氧电迁移是PCMO中非易失性电阻开关的相关机制。
