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Atomic structures of a liquid-phase bonded metal/nitride heterointerface
Akihito Kumamoto1, Naoya Shibata1, Kei-Ichiro Nayuki1
1Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
Scientific Reports
|March 11, 2016
Summary
Liquid-phase bonding of metal/ceramic heterostructures is key for power electronics. A novel layered structure with MgO and polarity-inverted AlN facilitates bonding between Al alloy and AlN single crystals.
Area of Science:
- Materials Science
- Nanotechnology
- Surface Science
Background:
- Liquid-phase bonding is crucial for fabricating metal/ceramic heterostructures for power electronics.
- Atomic-scale understanding of bonding mechanisms at dissimilar crystal interfaces remains limited.
Purpose of the Study:
- To elucidate the atomic-scale mechanisms governing liquid-phase bonding between Al alloy and AlN single crystals.
- To investigate the role of interfacial layers in facilitating the bonding of these materials.
Main Methods:
- Aberration-corrected scanning transmission electron microscopy (STEM) for atomically-resolved imaging.
- Energy-dispersive X-ray microanalysis in STEM for local chemical analysis.
- Density-functional-theory (DFT) calculations to assess bonding stability.
Main Results:
- A spontaneous monolayer of magnesium oxide (MgO) forms on the aluminum nitride (AlN) substrate.
- A polarity-inverted monolayer of AlN grows on the MgO layer.
- The Al alloy bonds with the polarity-inverted AlN monolayer, forming a complex layered structure.
Conclusions:
- The identified MgO and polarity-inverted AlN interfacial layers are critical for successful liquid-phase bonding.
- Bonding stability is significantly influenced by the polarity and stacking arrangement of these interfacial monolayers.
- Understanding these spontaneous layered structures is essential for developing highly reliable Al alloy/AlN heterostructures for power electronics.
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