1. MOCVD growth and band offsets of κ-phase Ga2O3 on c-plane sapphire, GaN- and AlN-on-sapphire, and (100) YSZ substrates.
- Author
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Bhuiyan, A F M Anhar Uddin, Feng, Zixuan, Huang, Hsien-Lien, Meng, Lingyu, Hwang, Jinwoo, and Zhao, Hongping
- Subjects
SCANNING transmission electron microscopy ,SAPPHIRES ,THIN films ,X-ray photoelectron spectroscopy ,CHEMICAL vapor deposition ,EPITAXY - Abstract
Epitaxial growth of κ-phase Ga
2 O3 thin films is investigated on c-plane sapphire, GaN- and AlN-on-sapphire, and (100) oriented yttria stabilized zirconia (YSZ) substrates via metalorganic chemical vapor deposition. The structural and surface morphological properties are investigated by comprehensive material characterization. Phase pure κ-Ga2 O3 films are successfully grown on GaN-, AlN-on-sapphire, and YSZ substrates through a systematical tuning of growth parameters including the precursor molar flow rates, chamber pressure, and growth temperature, whereas the growth on c-sapphire substrates leads to a mixture of β- and κ-polymorphs of Ga2 O3 under the investigated growth conditions. The influence of the crystalline structure, surface morphology, and roughness of κ-Ga2 O3 films grown on different substrates are investigated as a function of precursor flow rate. High-resolution scanning transmission electron microscopy imaging of κ-Ga2 O3 films reveals abrupt interfaces between the epitaxial film and the sapphire, GaN, and YSZ substrates. The growth of single crystal orthorhombic κ-Ga2 O3 films is confirmed by analyzing the scanning transmission electron microscopy nanodiffraction pattern. The chemical composition, surface stoichiometry, and bandgap energies of κ-Ga2 O3 thin films grown on different substrates are studied by high-resolution x-ray photoelectron spectroscopy (XPS) measurements. The type-II (staggered) band alignments at three interfaces between κ-Ga2 O3 and c-sapphire, AlN, and YSZ substrates are determined by XPS, with an exception of κ-Ga2 O3 /GaN interface, which shows type-I (straddling) band alignment. [ABSTRACT FROM AUTHOR]- Published
- 2022
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