The point defects and photoluminescence(PL)spectra of gallium nitride(GaN)epilayers with Mg,Zn,and unintentional doping were investigated in this study.The concentration of point defects(Ga vacancy and its related complexes)in the Zn-doped GaN is consistent with that in the Mg-doped GaN,but lower than that in undoped GaN.It is suggested that Zn(Mg)atoms occupy Ga sites and suppress the formation of Ga vacancies.Comparing the blue luminescence(BL)band intensity of GaN∶Zn with that of GaN:Mg,a factor of 10 strong PL intensity demonstrates that a moderate incorporation of Zn to GaN is likely to improve the structural quality of GaN.Detailed studies on 2.93 eV BL band for GaN∶Zn reveal that the Zn related BL band behaves as a donor-acceptor pairs character.For the acceptor level,isolated ZnGa with the activation energy of 0.386 eV above the valence band is obtained from tem-perature-dependent PL measurements,whereas the deep donor defect responsible for the 2.93 eV band is deduced to be 164 meV below the conduction band.An ON-H com-plex model is suggested to explain the deep donor origin.