GaN ultraviolet photovoltaic and photoconductive detectors were grown on sapphire substrates by metalorganic chemical vapor deposition. The spectral response was analyzed considering the detector structure of a p-n junction connected back-to-back with a Schottkty barrier. Based on the one-dimensional model of abrupt p-n junctions, the diffusion length of minority carriers was derived to be about 0.1 μm in n-GaN. To further characterize the n-GaN material, photoconductivity experiments have also been realized. The majority carrier lifetime of about 0.1 ms was obtained by analyzing the voltage-dependent responsivity of GaN photoconductors The current-responsivity under a bias of 8 V was about 1 A/W.