Direct observation of polarization-induced two-dimensional electron/hole gases at ferroelectric-insulator interface
Direct observation of polarization-induced two-dimensional electron/hole gases at ferroelectric-insulator interface
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DOI：
10.1038/s41535-021-00389-4
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发表时间：
2021-10-20
影响因子：
5.7
通讯作者：
Pan, Xiaoqing
中科院分区：
文献类型：
--
作者：
Huyan, Huaixun;Addiego, Christopher;Pan, Xiaoqing
近年来，二维电子气或空穴气（2DEG或2DHG）及其在人工异质结构界面上的功能引起了广泛的关注。许多理论计算和最近的实验研究表明，根据不同的极化状态，在铁电/绝缘体界面（例如 BiFeO3/TbScO3）会形成交替的 2DEG 和 2DHG。然而，基于 BiFeO3/TbScO3 界面局部电荷分布的直接观察仍有待探索。在此，我们展示了使用四维扫描透射电子显微镜和 Bader 电荷分析在 BiFeO3/TbScO3 界面直接观察 2DHG 和 2DEG。结果表明，测量到的界面处每个 Fe/O 柱的电荷态对于指向远离/朝向界面的偏振态发生了显着的增加/减少，表明 2DHG/2DEG 的存在。该方法开辟了一条在原子尺度上直接观察电荷的途径，并为未来电子纳米器件的设计提供了新的见解。
Two-dimensional electron gas or hole gas (2DEG or 2DHG) and their functionalities at artificial heterostructure interfaces have attracted extensive attention in recent years. Many theoretical calculations and recent experimental studies have shown the formation of alternating 2DEG and 2DHG at ferroelectric/insulator interfaces, such as BiFeO3/TbScO3, depending on the different polarization states. However, a direct observation based on the local charge distribution at the BiFeO3/TbScO3 interface has yet to be explored. Herein we demonstrate the direct observation of 2DHG and 2DEG at BiFeO3/TbScO3 interface using four-dimensional scanning transmission electron microscopy and Bader charge analysis. The results show that the measured charge state of each Fe/O columns at the interface undergoes a significant increase/reduction for the polarization state pointing away/toward the interface, indicating the existence of 2DHG/2DEG. This method opens up a path of directly observing charge at atomic scale and provides new insights into the design of future electronic nanodevices.