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/TbScO3interface has yet to be explored. Herein we demonstrate the direct observation of 2DHG and 2DEG at BiFeO3/TbScO3interface 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.
Interfaces play an important role in a variety of devices including transistors, solar cells, and memory components. Atomically sharp interfaces are essential to avoid charge traps that hamper efficient device operation. Sharp interfaces usually require thin‐film fabrication techniques involving ultrahigh vacuum and high substrate temperatures. A new self‐limiting wet chemical process for deposition of epitaxial layers from alkoxide precursors is presented. This method is fast, cheap, and yields perfect interfaces as validated by various analysis techniques. It allows the growth of heterostructures with half‐unit‐cell resolution. The method is demonstrated by designing a hole‐type oxide interface SrTiO3/BaO/LaAlO3. It is shown that transport through this interface exhibits properties of mixed electron–hole contributions with hole mobility exceeding that of electrons.
more » « less- NSF-PAR ID:
- 10042845
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 4
- Issue:
- 22
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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