Fig. 1. XPS spectra of Ga₂O₃，TiO₂ and TGO films

Fig. 2. XPS core level spectra of TiO₂ film

Fig. 3. XPS core level spectra of Ga₂O₃ film

Fig. 4. O 1s core level spectra of Ga₂O₃ and TGO films

Fig. 5. GIXRD spectra of Ga₂O₃ and TGO films

Fig. 6. AFM morphology of TGO film with Ga（3）Ti（1）

Fig. 7. Refractive index and extinction coefficient of Ti-doped Ga₂O₃ films deposited on silicon

Fig. 8. Optical transmittance of Ga₂O₃，TiO₂ and TGO thin films deposited on quartz

Fig. 9. Optical band gap of Ga₂O₃，TGO and TiO₂ films

Fig. 10. The O 1s peak and E_g for Ga₂O₃ and TGO films

Fig. 11. Comparison of the band gap of Ga₂O₃ and TGO films by SP and XPS methods