【Epitaxy Papers】The Origin of Enhanced Crystal Quality of Heteroepitaxially Grown (-201) β-Ga₂O₃ on Off-cut Sapphire Substrate by LI-MOCVD

      Researchers from the Slovak Academy of Sciences have published a dissertation titled "The Origin of Enhanced Crystal Quality of Heteroepitaxially Grown (-201) β-Ga₂O₃ on Off-cut Sapphire Substrate by LI-MOCVD" in 2025 IEEE 15th International Conference Nanomaterials: Applications & Properties (NAP).

Abstract

      Monoclinic gallium oxide (β-Ga₂O₃) is an ultrawide bandgap (UWBG) semiconductor material that has attracted significant attention due to its exceptional material properties, rendering it well-suited for a range of device applications, including predominantly power electronic devices but also gas sensors, UV photodetectors or nonlinear optical devices. To address the high cost of native substrates and excessive self-heating of homoepitaxial Ga₂O₃ devices, Ga₂O₃ is often grown heteroepitaxially, for example on sapphire, SiC, Si etc. In the case of foreign substrates exhibiting hexagonal surface symmetry, this can result in the formation of rotational domains (RDs) within the β-Ga₂O₃ layer. This phenomenon is known to compromise the crystal quality and impair the electric properties. To address this issue, the present study investigated the growth of (-201) β-Ga₂O₃ on vicinal c-plane sapphire substrates using the liquid-injection MOCVD technique. Multiple sapphire off-cuts (0°, 4°, 6°, 8°, 10°) towards a-plane were used and explored. A comprehensive structural, electrical, and optical characterisation of grown layers was conducted using a range of analytical techniques, including X-ray diffraction (XRD), atomic force microscopy, van der Pauw and Hall-effect measurements, and room temperature photoluminescence spectroscopy. While the RDs were not suppressed, the quality of the β-Ga₂O₃ crystal was greatly influenced by the use of off-cut substrates.

DOI：

https://doi.org/10.1109/NAP68437.2025.11216261