Solid-Phase Epitaxial Growth of an Alumina Layer Having a Stacking-Mismatched Domain Structure of the Intermediate gamma-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, pp.41487 - 41496
- Journal Title
- ACS APPLIED MATERIALS & INTERFACES
- Volume
- 10
- Number
- 48
- Start Page
- 41487
- End Page
- 41496
- URI
- https://scholarworks.bwise.kr/gachon/handle/2020.sw.gachon/83618
- 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 alpha-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 gamma-Al2O3 phase hinders the expected improved crystallinity of alpha-Al2O3, and thereby further enhancement of LED performance. Herein, we provide a fundamental understanding of the SPE growth mechanism from amorphous to metastable gamma-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 gamma-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 gamma-Al2O3 domains randomly nucleate from the alpha-Al2O3 substrate regardless of the alpha-Al2O3 termination layer, but the large energy requirement for reversal of the gamma-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 gamma- and alpha-Al2O3 films.
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