Impacts of oxygen source on band alignment of ALD Al2O3/(α-, ε-)Ga2O3 interface

• Published in: Journal of crystal growth 2022-02, Vol.580, p.126462, Article 126462
• Main Authors: Zuo, Yan, Feng, Qian, Zhang, Tao, Luo, HaiFeng, Tian, Xusheng, Cai, Yuncong, Gao, Yangyang, Zhang, Jincheng, Zhang, Chunfu, Zhou, Hong, Hao, Yue
• Format: Article
• Language: English
• Subjects: A1. Band alignment; A1. X-ray diffraction; A3. Oxygen source; Aluminum oxide; Atomic force microscopes; Atomic force microscopy; Atomic layer epitaxy; B1. Gallium compounds; B2. Dielectric materials; Chemical vapor deposition; Conduction bands; Electronic devices; Energy bands; Epitaxial growth; Gallium oxides; High resolution; High resolution electron microscopy; Microscopes; Offsets; Oxidizing agents; Oxygen plasma; Photoelectrons; Plasma; Pulsed laser deposition; Pulsed lasers; Sapphire; Spectrum analysis; Substrates; Valence band; X ray photoelectron spectroscopy
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2021.126462

•The Al2O3 films were deposited on (α-, ε-)Ga2O3 films by ALD with H2O, O3, O2 plasma.•The (α-, ε-)Ga2O3 films were epitaxially grown on α-Al2O3 by Mist-CVD and PLD.•The energy band diagrams of Al2O3/(α-,ε-)Ga2O3 were studied utilizing the XPS.•The ΔEC of Al2O3/(α-, ε-)Ga2O3 with different oxygen precursors are compared. Al2O3 films were deposited on α- and ε-Ga2O3 films by atomic layer deposition (ALD) in different plasma oxygen source (H2O, O3, O2 plasma). The α- and ε-Ga2O3 films were epitaxially grown on sapphire substrates by mist chemical vapor deposition (Mist-CVD) and pulsed laser deposition (PLD), respectively. The epilayer characteristics were investigated by high resolution X-ray diffraction (HRXRD), atomic force microscope (AFM) and high resolution transmission electron microscopy (HRTEM). Furthermore, the energy band diagrams of Al2O3/α-Ga2O3 and Al2O3/ε-Ga2O3 were investigated by X-ray photoelectron spectroscopy (XPS). On the basis of Ga 3d and Al 2p core-level spectra as well as α- and ε-Ga2O3 valence band spectra, the energy band diagrams of Al2O3/α-Ga2O3 and Al2O3/ε-Ga2O3 interface were determined. And the conduction band offset of Al2O3/α-Ga2O3 interfaces were estimated to be 1.21/1.31/1.27 eV for oxidant of H2O, O3 and O2 plasma, respectively, while that of Al2O3/ε-Ga2O3 were 1.61/1.72/1.7 eV, the conduction band offsets of Al2O3 grown by O3 and O2 plasma were higher than those grown by H2O. And, the conduction band offsets of all samples were greater than 1 eV, indicating that Al2O3 grown by ALD can be used as gate dielectric in (α-, ε-) Ga2O3 power device.