Fig. 1. Schematic illustration the mist-CVD system used for α-Ga₂O₃ epitaxy.

Fig. 2. (Color online) X-ray diffraction (XRD) 2θ/ω scan spectrum of the thick α-Ga₂O₃ epilayer. The inset displays the ω-scan rocking curves of (0006) and (10-14) planes under symmetric and skew-symmetric scan configuration, respectively.

Fig. 3. (Color online) XRD Φ-scan measurement for the (10-14) plane of the α-Ga₂O₃ epilayer and α-Al₂O₃ substrate.

Fig. 4. (Color online) (a) Optical microscopic image. (b) Large-scale atomic force microscopic image of the α-Ga₂O₃ epilayer. (c) Cross-sectional profile of grain. (d) AFM image of side facet of grain.

Fig. 5. (Color online) (a) The derived (αhv)^1/2 curve as a function of photon energy and the inset displays the optical transmittance spectrum. (b) Raman scattering spectra of the α-Ga₂O₃ epilayer and α-Al₂O₃ substrate.