Persistent photoconductivity in n-type GaN

Results of photoconductivity measurements in undoped n-type and Se-doped GaN epitaxial thin films are presented. Similar to the photoluminescence spectra, the photoconductivity also shows a broad yellow band centered around 2.2 eV. It is found that persistent photoconductivity (PPC) does exist in all the studied thin films. In addition, the PPC effects can be observed for the pumping photon energy down to the yellow band. The results reveal that the origin of the PPC effect and yellow luminescence may arise from the same intrinsic defect. It is shown that the most probable candidate of the intrinsic defect is nitrogen antisite.