Electron Spin Resonance and Photoluminescence Studies of Carbon‐Induced Point Defects in GaN: Influence of Doping Concentration and Method

The potential to modify the substitution of carbon (C) atom for gallium (Ga) or nitrogen (N) or the occupancy of the interstitial site for the different methods of C doping in gallium nitride is investigated. Herein, two types of samples with C doping concentrations of 1 × 10 17 , 1 × 10 18 , and 1 × 10 19 cm −3 are prepared by supplying acetylene (C 2 H 2 ) gas during growth and C autodoping. Based on the analysis of electron spin resonance and photoluminescence, it appears that the point defect generated by C substitution for the N site (C N ) is formed in the C‐doped sample with C 2 H 2 gas at C concentration of 1 × 10 17 cm −3 , and the defect changes to the C interstitial (C i ) at C concentrations of 1 × 10 18 –1 ×10 19 cm −3 . In contrast, the C i defect is formed in the C autodoped samples at C concentrations of 1 × 10 17 –1 × 10 18 cm −3 and changed to the C N defect at C concentration of 1 × 10 19 cm −3 . These results indicate the possibility that the formation mechanism of yellow luminescence band is different depending on the C doping method even at the same C concentration.