GaN-based metal-insulator-semiconductor (MIS) AlGaN/GaN ultraviolet (UV) photodetectors with photo-chemical vapor deposition (Photo-CVD) SiO2 insulator and AR-coating layer were fabricated. It was found that with a 5 V applied bias, photocurrent to dark current contrast ratio was 1.27 x 10(4) for the MIS photodetector with AR-coating. It was also found that UV-to-visible rejection ratio of such MIS photodetector with AR-coating was more than 3 orders of magnitude while the responsivity was 0.144 A/W with a 5 V applied bias and a 3 50 nm incident light wavelength. (c) 2005 Elsevier B.V. All rights reserved.