Fig. 1. (Color online) XRD patterns ofβ-Ga₂O₃ films deposited onc-plane Al₂O₃ substrates with different off-axis angles toward < 112¯0>.

Fig. 2. (Color online) (a) XRD rocking curves of the ( 2¯01) diffraction peaks ofβ-Ga₂O₃ films deposited onc-plane Al₂O₃ substrates with different off-axis angles toward < 112¯0>, (b) FWHM as a function of off-axis angles of Al₂O₃ substrates.

Fig. 3. Cross-sectional TEM of the film deposited on an 8° off-axis sapphire substrate with a thickness of 300 nm. (a) Image of the whole film. (b) HRTEM micrograph of the interface. (c) Selected area electron diffraction (SAED) obtained by Fourier transform of area B. (d) Selected area electron diffraction (SAED) obtained by Fourier transform of area A.

Fig. 4. (Color online) 10 × 10μm² AFM patterns ofβ-Ga₂O₃ films deposited on (a) 0°, (b) 4°, (c) 6° and (d) 8° off-axis Al₂O₃ substrates. All films were annealed in-situ for 10 min under an oxygen atmosphere.

Fig. 5. SEM ofβ-Ga₂O₃ thin films on Al₂O₃ substrates with (a) 0°, (b) 4°, (c) 6°, and (d) 8° off-angles toward < 112¯0>.

Fig. 6. (Color online) (a) Room temperature PL spectra of all films grown on off-angled Al₂O₃ substrates. The broad emission band from ultraviolet to blue of theβ-Ga₂O₃ film deposited on (b) 4°, (c) 6°, and (d) 8° can be divided into two emission peaks near 365 and 410 nm.