We study the performance of GaN-based p–i–n ultraviolet(UV) photodetectors(PDs) with a 60 nm thin ptype contact layer grown on patterned sapphire substrate(PSS). The PDs on PSS exhibit a low dark current of ~2 pA under a bias of-5 V, a large UV/visible rejection ratio of ~7×103, and a high-quantum efficiency of ~40% at 365 nm under zero bias. The average quantum efficiency of the PDs still remains above 20% in the deep-UV region from 280 to 360 nm. In addition, the noise characteristics of the PDs are also discussed, and the corresponding specific detectivities limited by the thermal noise and the low-frequency 1/f noise are calculated. We study the performance of GaN-based p-i-n ultraviolet (UV) photodetectors (PDs) with a 60 nm thin ptype contact layer grown on patterned sapphire substrate (PSS). The PDs on PSS exhibit a low dark current of ~ 2 pA under a bias of-5 V, a large UV / visible rejection ratio of ~7 × 103, and a high-quantum efficiency of ~ 40% at 365 nm under zero bias. The average quantum efficiency of the PDs still remains above 20 % of the deep-UV region from 280 to 360 nm. In addition, the noise characteristics of the PDs are also discussed, and the corresponding specific detections are limited by the thermal noise and the low-frequency 1 / f noise are calculated.