【Epitaxy Papers】Effect of surface offset angle on NiO initial growth on β-Ga₂O₃ by mist chemical vapor deposition

      Researchers from the Kyoto Institute of Technology have published a dissertation titled "Effect of surface offset angle on NiO initial growth on β-Ga₂O₃ by mist chemical vapor deposition" in Applied Surface Science.

Abstract

      We investigated the crystallinity, orientations, and electronic properties of NiO layers grown via mist chemical vapor deposition on two β-Ga₂O₃(-201) substrates with different surface offset angles: an unintentional 0.3° and an intentional 0.7° along the [102] direction. Structural and morphological analyses using scanning electron microscopy, atomic force microscopy, and X-ray diffraction revealed that NiO layers grown on the 0.7° offset-angled substrate exhibited better crystallinity and higher orientation, suggesting that the surface offset angle, that is, terrace width, significantly influences the crystal quality of the grown layer. Band alignments derived from optical transmission spectroscopy and X-ray photoelectron spectroscopy indicated that the valence band maxima and conduction band minima discontinuities were larger for NiO grown on the 0.7° offset substrate. This was attributed to volumetric stress at the interface, which induces interfacial defects. These findings suggest that a surface offset angle between 0.3° and 0.7° significantly affects growth mechanism, with an optimal angle within this range yielding the highest crystallinity and orientation.

DOI：

https://doi.org/10.1016/j.apsusc.2025.163977