Characterization of Zn-doped GaN grown by metal–organic vapor phase epitaxy

Abstract

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 temperature-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 complex model is suggested to explain the deep donor origin.