Solar-blind UV photoelectric properties of pure-phase α-Ga 2 O 3 deposited on m-plane sapphire substrate

α-Ga 2 O 3 film deposited on m-plane sapphire substrate by RF magnetron sputtering method was used to fabricate a solar-blind UV PD with traditional MSM structure. The optimum deposition temperature of the pure-phase (300) α-Ga 2 O 3 film was confirmed to be 775 ℃ from the XRD, AFM and deposition rate analyses. The bandgap of the prepared α-Ga 2 O 3 film was estimated to be 5.3 eV from the optical absorbance measurement. The (300) α-Ga 2 O 3 film based PD exhibited a responsivity of 659.6 A/W and a photo-to-dark ratio of 1554 under 254 nm light illumination. The response time constants at bias voltage of 5 V were estimated to be (0.28, 1.52 s) and (0.04, 0.62 s), respectively.