The effects of magnesium ion implantation and post-annealing on the photoelectric performance of a β-G a 2 O 3-based vertical structural Schottky photodetector (PD) were thoroughly investigated. After implantation and post-annealing, the Schottky barrier height and bandgap of the G a 2 O 3 surface can be slightly increased, while the dark current is significantly reduced, and the light-to-dark current ratio is immensely improved. The PD exhibited a photo-to-dark current ratio of 1733, responsivity of 5.04 mA/W, and specific detectivity of 3.979×1011 Jones under -2.6V bias, and the rise and decay times are 0.157 were 0.048 s, respectively. The large left shift of the open-circuit voltage is feasibly explained by applying the thermionic-emission diffusion theory.