We report successful development of both discrete ultraviolet (UV) photodiodes and UV imagers consisting of 8 X 8 backside-illuminated AlGaN p-i-n photodiode arrays. The discrete AlGaN p-i-n photodiodes showed a responsivity of 0.1 A/W, a cutoff wavelength of 350 nm, an external quantum efficiency of 35%, and a response time of 4.1 ns. Then, 8 X 8 AlGaN p-i-n photodiode arrays were fabricated, followed by hybridizations with readout integrated circuits manufactured using a 0.5 mu m 2poly-3metal N-well complementary metal-oxide semiconductor process by gold stud bumping. The 8 X 8 focal plane array UV imagers operated successfully by sensing radiation in the 300-350 nm spectral bands. (c) 2006 American Vacuum Society.