Two-inch Ga2O3 films with ( 201)-orientation are grown on 𝑐-sapphire at 850-1050 ∘ C by hydride vapor phase epitaxy. High-resolution x-ray diffraction shows that pure 𝛽-Ga2O3 with a smooth surface has a higher crystal quality, and the Raman spectra reveal a very small residual strain in 𝛽-Ga2O3 grown by hydride vapor phase epitaxy compared with bulk single crystal. The optical transmittance is higher than 80% in the visible and near-UV regions, and the optical bandgap energy is calculated to be 4.9 eV.

Halide vapor phase epitaxy (HVPE) is widely used in the semiconductor industry for the growth of Si, GaAs, GaN, etc. HVPE is a non-organic chemical vapor deposition (CVD) technique, characterized by high quality growth of epitaxial layers with fast growth rate, which is versatile for the fabrication of both substrates and devices with wide applications. In this paper, we review the usage of HVPE for the growth and device applications of Ga2O3, with detailed discussions on a variety of technological aspects of HVPE. It is concluded that HVPE is a promising candidate for the epitaxy of large-area Ga2O3 substrates and for the fabrication of high power β-Ga2O3 devices.

Hexagonal GaN has been obtained by nitridating β-Ga2O3 film despite structural mismatch between β-Ga2O3 and GaN, and the conversion process has been investigated systematically.

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