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Plasma-Assisted Molecular Beam Epitaxy Growth of Mg3N2 and Zn3N2 Thin Films
Published on: May 11, 2019
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MnO(001) thin films on MgO(001) grown by reactive MBE using supersonic molecular beams
Andrew J Pedersen1, Junchen Liu1, Fanxing Li1
1Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, USA.
The Journal of Chemical Physics
|April 17, 2024
Summary
Epitaxial manganese oxide (MnO) thin films were grown using supersonic molecular beams. Different radio frequency plasma conditions altered film morphology and composition, leading to Mn3O4 formation or specific surface features in MnO films.
Area of Science:
- Materials Science
- Thin Film Growth
- Surface Science
Background:
- Manganese oxide (MnO) thin films are crucial for various electronic applications.
- Controlling the growth and properties of MnO films is essential for device performance.
- Epitaxial growth on MgO substrates offers a pathway to high-quality oxide films.
Purpose of the Study:
- To investigate the growth of epitaxial MnO(001) thin films on MgO(001) substrates using reactive molecular beam epitaxy (MBE).
- To explore the effects of radio frequency (RF) plasma excitation and oxygen atom exposure on MnO film growth and surface morphology.
- To characterize the structural and chemical properties of the synthesized MnO films.
Main Methods:
- Reactive molecular beam epitaxy (MBE) with Mn vapor and O2-seeded supersonic molecular beams (SMBs).
- Radio frequency (RF) plasma excitation and RF-discharge (RFD) SMB source for oxygen atom generation.
- X-ray photoelectron spectroscopy (XPS) for chemical state analysis.
- Reflection high-energy electron diffraction (RHEED) and X-ray diffraction (XRD) for structural characterization.
- High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) with energy-dispersive X-ray spectroscopy (EDS) for interface analysis.
- Atomic force microscopy (AFM) for surface morphology evaluation.
Main Results:
- Epitaxial MnO(001) films with strong (001) orientation were successfully grown on MgO(001) substrates.
- XPS confirmed Mn2+ oxidation state with slight excess oxygen.
- HAADF-STEM revealed abrupt MnO/MgO interfaces with epitaxial alignment.
- Post-growth exposure to RFD-SMB converted MnO to Mn3O4 with (110) orientation and surface pits.
- Growth using RFD-SMB resulted in MnO films with characteristic surface pits and hillocks.
Conclusions:
- Supersonic molecular beam epitaxy is effective for growing epitaxial MnO(001) films.
- RF plasma excitation and oxygen atom exposure significantly influence MnO film growth pathways and surface morphology.
- Controlled conversion to Mn3O4 or specific surface structuring of MnO is achievable through post-growth treatment or modified growth conditions.
