Solid-phase epitaxial growth of an alumina layer having a stacking-mismatched domain structure of the intermediate γ-phase
- Authors
- Jang, Jeonghwan; Lee, Seung Yong; Park, Hwanyeol; Yoon, Sangmoon; Park, Gyeong-Su; Lee, Gun-Do; Park, Yongjo; Kim, Miyoung; Yoon, Euijoon
- Issue Date
- Dec-2018
- Publisher
- AMER CHEMICAL SOC
- Keywords
- solid-phase epitaxy; aluminum oxide; double-positioning domains; transmission electron microscopy; density functional theory calculations
- Citation
- ACS APPLIED MATERIALS & INTERFACES, v.10, no.48
- Indexed
- SCIE
SCOPUS
- Journal Title
- ACS APPLIED MATERIALS & INTERFACES
- Volume
- 10
- Number
- 48
- URI
- https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/15214
- DOI
- 10.1021/acsami.8b13818
- ISSN
- 1944-8244
- Abstract
- Solid-phase epitaxy (SPE), a solid-state phase transition of materials from an amorphous to a crystalline phase, is a convenient crystal growing technique. In particular, SPE can be used to grow α-Al₂O₃ epitaxially with a novel structure that provides an effective substrate for improved performance of light-emitting diodes (LEDs). However, the inevitable two-step phase transformation through the γ-Al₂O₃ phase hinders the expected improved crystallinity of α-Al₂O₃ , and thereby further enhancement of LED performance. Herein, we provide a fundamental understanding of the SPE growth mechanism from amorphous to metastable γ-Al₂O₃ using transmission electron microscopy (TEM) and density functional theory (DFT) calculations. The nanobeam precession electron diffraction technique enabled clear visualization of the double-positioning domain distribution in the SPE γ-Al₂O₃ film and emphasized the need for careful selection of the viewing directions for any investigation of double-positioning domains. Void and stacking fault defects further investigated by high-resolution scanning TEM (STEM) analyses revealed how double-positioning domains and other SPE growth behaviors directly influence the crystallinity of SPE films. Additionally, DFT calculations revealed the origins of SPE growth behavior. The double-positioning γ-Al₂O₃ domains randomly nucleate from the α-Al₂O₃ substrate regardless of the α-Al₂O₃ termination layer, but the large energy requirement for reversal of the γ-Al₂O₃ stacking sequence prevents it from switching the domain type during the crystal growth. We expect that this study will be useful to improve the crystallinity of SPE γ- and α-Al₂O₃ films.
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