Epitaxial Growth of δ‐Ga2O3 Thin Films Grown on YSZ and Sapphire Substrates Using β‐Fe2O3 Buffer Layers via Mist Chemical Vapor Deposition

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2024-07, Vol.221 (13), p.n/a
• Main Authors: Kato, Takahiro, Nishinaka, Hiroyuki, Shimazoe, Kazuki, Yoshimoto, Masahiro
• Format: Article
• Language: English
• Subjects: Buffer layers; Chemical vapor deposition; Crystal growth; Crystal lattices; Crystal structure; Epitaxial growth; Ga2O3; Gallium oxides; Grain size; Indium oxides; mist chemical vapor deposition; Sapphire; Substrates; Thermal instability; Thin films; X-ray diffraction; Yttria-stabilized zirconia; Yttrium oxide; Zirconium dioxide; β-Fe2O3; δ-epitaxial growths
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.202300582

Herein, epitaxial δ‐Ga2O3 thin films are successfully grown on various planes of yttria‐stabilized zirconia (YSZ) and c‐plane sapphire substrates by inserting the same crystal‐structured β‐Fe2O3 and bcc‐In2O3 buffer layers via mist chemical vapor deposition. X‐ray diffraction (XRD) measurements reveal that various planes of δ‐Ga2O3 thin films are grown in both the out‐of‐plane and in‐plane orientations using the same crystal‐structured buffer layers to reduce the lattice mismatch. δ‐Ga2O3 (111) is demonstrated to grow on the YSZ (111) in the narrow growth temperature range of 575–675 °C due to thermal instability of β‐Fe2O3 buffer layers. Next, a c‐plane sapphire wafer as a substrate using two buffer layers for the growth of δ‐Ga2O3 is investigated. XRD 2θ–ω scan reveals that the mixture of α‐ and δ‐Ga2O3 thin films is grown on Fe2O3/In2O3/c‐plane sapphire. This is because the Fe2O3 buffer layers are phase separated into α and β phases due to the large grain size of the In2O3 buffer layer. XRD φ‐scan profiles indicate that the δ‐Ga2O3 thin film grown on sapphire is composed of a twin domain. This study contributes to our understanding of the growth mechanism of δ‐Ga2O3 and its future applications in devices. Herein, the δ‐Ga2O3 epitaxial thin films are fabricated on various planes of YSZ and c‐plane sapphire substrates using β‐Fe2O3 and bcc‐In2O3 buffer layers via mist chemical vapor deposition. The β‐Fe2O3 buffer layer with small lattice mismatch for δ‐Ga2O3 (≈1.6%) plays an important role in the growth of δ‐Ga2O3 thin films.