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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2405.00299 |
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| _version_ | 1866914778648150016 |
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| author | Tang, J. Jiang, K. Tseng, P. Kurchin, R. C. Porter, L. M. Davis, R. F. |
| author_facet | Tang, J. Jiang, K. Tseng, P. Kurchin, R. C. Porter, L. M. Davis, R. F. |
| contents | Phase transitions in metastable $α$-, $κ(ε)$-, and $γ$-Ga$_2$O$_3$ films to thermodynamically stable $β$-Ga$_2$O$_3$ during annealing in air, N$_2$, and vacuum have been systematically investigated via in-situ high-temperature X-ray diffraction and scanning electron microscopy. These respective polymorphs exhibited thermal stability to around 471-525$^\circ$C, 773-825$^\circ$C, and 490-575$^\circ$C before transforming into $β$-Ga$_2$O$_3$, across all tested ambient conditions. Particular crystallographic orientation relationships were observed before and after the phase transitions, i.e., (0006) $α$-Ga$_2$O$_3$ $\parallel$ $(\overline{4}02)$ $β$-Ga$_2$O$_3$, (004) $κ(ε)$-Ga$_2$O$_3$ $\parallel$ (310) and $(\overline{4}02)$ $β$-Ga$_2$O$_3$, and (400) $γ$-Ga$_2$O$_3$ $\parallel$ (400) $β$-Ga$_2$O$_3$. The phase transition of $α$-Ga$_2$O$_3$ to $β$-Ga$_2$O$_3$ resulted in catastrophic damage to the film and upheaval of the surface. The respective primary and possibly secondary causes of this damage are the +8.6% volume expansion and the dual displacive and reconstructive transformations that occur during this transition. The $κ(ε)$- and $γ$-Ga$_2$O$_3$ films converted to $β$-Ga$_2$O$_3$ via singular reconstructive transformations with small changes in volume and unchanged surface microstructures. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_00299 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Thermal stability and phase transformation of $α$-, $κ(ε)$-, and $γ$-Ga$_2$O$_3$ thin films to $β$-Ga$_2$O$_3$ under various ambient conditions Tang, J. Jiang, K. Tseng, P. Kurchin, R. C. Porter, L. M. Davis, R. F. Materials Science Applied Physics Phase transitions in metastable $α$-, $κ(ε)$-, and $γ$-Ga$_2$O$_3$ films to thermodynamically stable $β$-Ga$_2$O$_3$ during annealing in air, N$_2$, and vacuum have been systematically investigated via in-situ high-temperature X-ray diffraction and scanning electron microscopy. These respective polymorphs exhibited thermal stability to around 471-525$^\circ$C, 773-825$^\circ$C, and 490-575$^\circ$C before transforming into $β$-Ga$_2$O$_3$, across all tested ambient conditions. Particular crystallographic orientation relationships were observed before and after the phase transitions, i.e., (0006) $α$-Ga$_2$O$_3$ $\parallel$ $(\overline{4}02)$ $β$-Ga$_2$O$_3$, (004) $κ(ε)$-Ga$_2$O$_3$ $\parallel$ (310) and $(\overline{4}02)$ $β$-Ga$_2$O$_3$, and (400) $γ$-Ga$_2$O$_3$ $\parallel$ (400) $β$-Ga$_2$O$_3$. The phase transition of $α$-Ga$_2$O$_3$ to $β$-Ga$_2$O$_3$ resulted in catastrophic damage to the film and upheaval of the surface. The respective primary and possibly secondary causes of this damage are the +8.6% volume expansion and the dual displacive and reconstructive transformations that occur during this transition. The $κ(ε)$- and $γ$-Ga$_2$O$_3$ films converted to $β$-Ga$_2$O$_3$ via singular reconstructive transformations with small changes in volume and unchanged surface microstructures. |
| title | Thermal stability and phase transformation of $α$-, $κ(ε)$-, and $γ$-Ga$_2$O$_3$ thin films to $β$-Ga$_2$O$_3$ under various ambient conditions |
| topic | Materials Science Applied Physics |
| url | https://arxiv.org/abs/2405.00299 |