Atomic scale investigation of aluminum incorporation, defects, and phase stability in β-(AlxGa1−x)2O3 films
In: APL Materials ; volume 9, issue 5 ; ISSN 2166-532X, 2021
academicJournal
Zugriff:
The development of novel ultra-wide bandgap (UWBG) materials requires precise understanding of the atomic level structural origins that give rise to their important properties. We study the aluminum atom incorporation, defect formation, and their relationships with phase stability in β-(AlxGa1−x)2O3 films, a promising candidate for UWBG applications, to explain atomic scale structural characteristics and properties using a combination of quantitative scanning transmission electron microscopy (STEM) and density functional theory (DFT). Our STEM analysis indicates that ∼54% of the incorporated Al substitutes on the octahedrally coordinated Ga2 site in a series of films grown with different techniques and alloy concentrations. DFT calculations show that, while Al energetically prefers the octahedral site, surface reconstructions and kinetic limitations during the epitaxial growth are responsible for Al occupying both octahedral and tetrahedral sites in (AlxGa1−x)2O3, ultimately limiting the stability of the β-phase at x < ∼50%. Local heterogeneity of composition results in the formation of a planar defect, affecting the stability of the β-phase. The similarity of such inclusions to the metastable γ-phase is discussed.
Titel: |
Atomic scale investigation of aluminum incorporation, defects, and phase stability in β-(AlxGa1−x)2O3 films
|
---|---|
Autor/in / Beteiligte Person: | Johnson, Jared M. ; Huang, Hsien-Lien ; Wang, Mengen ; Mu, Sai ; Varley, Joel B. ; Uddin Bhuiyan, A F M Anhar ; Feng, Zixuan ; Kalarickal, Nidhin Kurian ; Rajan, Siddharth ; Zhao, Hongping ; Van de Walle, Chris G. ; Hwang, Jinwoo ; Air Force Office of Scientific Research ; National Science Foundation ; U.S. Department of Energy |
Link: | |
Zeitschrift: | APL Materials ; volume 9, issue 5 ; ISSN 2166-532X, 2021 |
Veröffentlichung: | AIP Publishing, 2021 |
Medientyp: | academicJournal |
DOI: | 10.1063/5.0039769 |
Sonstiges: |
|