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Tuning Oxide Properties by Oxygen Vacancy Control During Growth and Annealing
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Tailoring the Two Dimensional Electron Gas at Polar ABO3/SrTiO3 Interfaces for Oxide Electronics
Changjian Li1,2, Zhiqi Liu1,3, Weiming Lü1
1NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.
Scientific Reports
|August 27, 2015
Summary
A critical thickness of 4 unit cells drives the metal-insulator transition in polar/non-polar oxide interfaces, enabling novel electronic devices. This transition occurs at a specific growth temperature, offering integration possibilities with silicon.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid State Chemistry
Background:
- The two-dimensional electron gas (2DEG) at polar/non-polar oxide interfaces is crucial for advanced oxide electronic devices.
- Perovskite oxide interfaces, such as ABO3/SrTiO3 (STO), are key platforms for exploring emergent electronic phenomena.
Purpose of the Study:
- Investigate the transport properties of various ABO3/STO interfaces with crystalline and amorphous polar layers.
- Determine the critical thickness for the metal-insulator transition (MIT) in these heterostructures.
- Explore the influence of material composition and growth conditions on 2DEG formation.
Main Methods:
- Fabrication of crystalline and amorphous ABO3/STO heterostructures using techniques like pulsed laser deposition.
- Characterization of transport properties, including conductivity and carrier density.
- Analysis of the relationship between critical thickness, material properties (B-site atom, oxygen affinity), and growth temperature.
Main Results:
- A consistent 4 unit cell critical thickness for MIT was observed at crystalline polar layer/STO interfaces.
- The critical thickness for amorphous interfaces varied significantly based on the B-site atom and its oxygen affinity.
- A sharp transition to a metallic state was achieved at 515°C for crystalline interfaces, linked to a critical relative crystallinity of ~70% for LaAlO3 overlayers.
Conclusions:
- The study establishes a critical thickness for MIT in crystalline ABO3/STO interfaces, crucial for device design.
- Amorphous interface MIT is tunable by selecting appropriate B-site elements, offering material design flexibility.
- The observed low-temperature transition facilitates the integration of oxide heterojunction devices with silicon technology.
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