TY - JOUR
T1 - Interfacial area between hetero-epitaxial γ-Al2O3 and silicon
AU - Liao, Yuanxun
AU - Zhou, Dongyi
AU - Shrestha, Santosh
AU - Huang, Shujuan
AU - Bremner, Stephen
AU - Conibeer, Gavin
PY - 2017/9/8
Y1 - 2017/9/8
N2 - The interfacial region between hetero-epitaxial γ-Al2O3 and Si (111) substrates is studied in detail. The purpose is to address many open questions regarding the growth of γ-Al2O3 grown on Si, such as the atomic stacking orders, strain relaxation modes, and observed thin-film qualities. The cross-sectional atomic stacking order is directly evidenced to be a cubic spinel structure, with a possible in-plane stacking order proposed. A 1.5 nm defect-rich transition layer is found at the interface, in which the lattice structure transitions from Si to γ-Al2O3 arrangement. The thin-film quality, in terms of crystallinity and low film roughness, is observed to improve with increasing thickness up to ≈8 nm. For thicknesses above 8 nm, grain boundaries are observed along with the appearance of pinholes, due to the large lattice constant and thermal expansion coefficient differences between γ-Al2O3 and Si. Polycrystalline islands form in these pinholes and gradually replace the initial layer-by-layer growth of monocrystalline γ-Al2O3, leading to a mainly polycrystalline material at large thicknesses. The insights gained on the hetero-epitaxy of γ-Al2O3 on Si will be useful for future work looking to exploit this hetero-epitaxial materials system.
AB - The interfacial region between hetero-epitaxial γ-Al2O3 and Si (111) substrates is studied in detail. The purpose is to address many open questions regarding the growth of γ-Al2O3 grown on Si, such as the atomic stacking orders, strain relaxation modes, and observed thin-film qualities. The cross-sectional atomic stacking order is directly evidenced to be a cubic spinel structure, with a possible in-plane stacking order proposed. A 1.5 nm defect-rich transition layer is found at the interface, in which the lattice structure transitions from Si to γ-Al2O3 arrangement. The thin-film quality, in terms of crystallinity and low film roughness, is observed to improve with increasing thickness up to ≈8 nm. For thicknesses above 8 nm, grain boundaries are observed along with the appearance of pinholes, due to the large lattice constant and thermal expansion coefficient differences between γ-Al2O3 and Si. Polycrystalline islands form in these pinholes and gradually replace the initial layer-by-layer growth of monocrystalline γ-Al2O3, leading to a mainly polycrystalline material at large thicknesses. The insights gained on the hetero-epitaxy of γ-Al2O3 on Si will be useful for future work looking to exploit this hetero-epitaxial materials system.
KW - γ-Al₂O₃
KW - hetero-epitaxy
KW - oxide-on-silicon
KW - pulsed laser deposition
UR - http://www.scopus.com/inward/record.url?scp=85023176218&partnerID=8YFLogxK
U2 - 10.1002/admi.201700259
DO - 10.1002/admi.201700259
M3 - Article
AN - SCOPUS:85023176218
SN - 2196-7350
VL - 4
JO - Advanced Materials Interfaces
JF - Advanced Materials Interfaces
IS - 17
M1 - 1700259
ER -