[en] Ga_2−x Sn_x O₃ thin films on m-plane (300) sapphire substrates were deposited by laser molecular beam epitaxy technology. Corundum-structured α -phase Ga_2−x Sn_x O₃ thin films with different Sn content were obtained at 850 °C in vacuum pressure of 5 × 10⁻⁵ Pa. The band-gap energy of the  α -phase Ga_2−x Sn_x O₃ thin films, determined from the absorption spectrum, decreases linearly with increasing Sn content. A metal–semiconductor–metal structured solar-blind photodetector based α -phase Ga_2−x Sn_x O₃ thin films was fabricated, and excellent solar-blind ultraviolet characteristics were demonstrated. The ratio of I₂₅₄/ I _dark was up to 1.40 × 10² and the responsivity increased to 9.55 × 10⁻² A W⁻¹. The results suggest that α -phase Ga_2−x Sn_x O₃ thin films are promising candidates for use in solar-blind photodetectors. (paper)