AlGaN-based resonant-cavity-enhanced (RCE) p-i-n junction photodetectors (PDs) operating at the wavelength of 330 nm are fabricated by metal organic chemical vapor deposition (MOCVD). The growth and characterization of AlN/Al0.3Ga0.7N distributed Bragg reflectors(DBRs) are investigated firstly. It is shown that with increasing the pairs of the bi-layers, the reflectance of AlN/AlGaN DBR is elevated, but the stop band width is depressed. For grown RCE PDs structure, a 20.5-pair AlN/Al0.3Ga0.7N DBR is selected as the back mirror and 3-pair AlN/Al0.3Ga0.7N DBR as the front one to form an optical micro-cavity. A p-GaN/i-GaN/n-Al0.3Ga0.7N junction structure is used as active layers within the cavity. The optical absorption of the RCE PD structure is approximately 59.8% determined by reflectance measurement. Selectively enhanced by the cavity effect, a response peak of 0.128 A/W at 330 nm with external quantum efficiency of 48% is obtained under zero bias. The peak wavelength shifted 15 nm with the incident angle of light increasing from 0° to 60°, which suggests that the detection wavelength can be tuned by controlling the angle of incoming light (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)