The electrical and optical characteristics of GaN:Mg irradiated by a pulsed KrF (248 nm) excimer laser have been studied. When an as-grown Mg-doped GaN film was irradiated by an excimer laser at an energy density of 590 mJ/cm(2) in a nitrogen atmosphere, the hole concentration was drastically increased up to 4.42 x 10(17) cm(-3). Furthermore, a GaN:Mg thin film, which was treated by laser irradiation following a conventional rapid thermal annealing process, showed a very high hole concentration of 9.42 x 10(17) cm(-3). The GaN:Mg samples, which were activated in a nitrogen ambient by the KrF excimer laser irradiation, showed two photoluminescence peaks at 2.95 eV and 2.7 eV. The intensities of both photoluminescence peaks were increased wit h increasing laser energy density and number of pulses. The changes in photoluminescence peaks depending on the laser energy density further suggest that the pulsed KrF excimer laser irradiation dissociates the Mg-H complexes and allows the hydrogens to diffuse out, thus significantly enhancing the p-type conductivity of GaN:Mg. (C) 2003 American Vacuum Society.