| Autor: |
Charlotte Wouters, Musbah Nofal, Piero Mazzolini, Jijun Zhang, Thilo Remmele, Albert Kwasniewski, Oliver Bierwagen, Martin Albrecht |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
|
| Zdroj: |
APL Materials, Vol 12, Iss 1, Pp 011110-011110-10 (2024) |
| Druh dokumentu: |
article |
| ISSN: |
2166-532X |
| DOI: |
10.1063/5.0182500 |
| Popis: |
In this paper, we employ in situ transmission electron microscopy to study the disorder–order phase transition from amorphous Ga2O3 to γ-Ga2O3 and then to β-Ga2O3. The in situ studies are complemented by ex situ annealing experiments, of which the results are analyzed by x-ray diffraction and high resolution (scanning) transmission electron microscopy. Amorphous Ga2O3 deposited at 100 °C by molecular beam epitaxy crystallizes at 470 °C in the γ phase (Fd3̄m), which undergoes a phase transition to the β phase above 500 °C. Between 500° and 900 °C, we find a mixture of γ-Ga2O3 and β-Ga2O3 coexisting. Above 950 °C, we find only β-Ga2O3. Through our analyses and by considering symmetry relations, we have constructed a coincidence site lattice of both structures containing a common fcc-type sublattice occupied by oxygen atoms, the cation sites of β-Ga2O3 common to both phases, and partially occupied cation sites in the γ phase corresponding to the interstitial sites in the β phase. We assign the atomic displacements within this lattice responsible for transforming the initially disordered spinel structure with partially occupied cation sites into the well-ordered lattice of β-Ga2O3. We identify this transition as a reconstructive disorder-to-order phase transition, mediated by the exchange of cations to next nearest neighbor sites. Our model not only explains recent observations of the formation of γ-Ga2O3 during implantation for n-type doping and the subsequent recovery of β-Ga2O3 following annealing but also holds potential for inspiring understanding in other materials with similar phase transitions. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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