Detailed deep trap analysis in Mg-doped p-type GaN layers grown by MOVPE

p-Type Mg-doped GaN layers grown by metal organic vapor phase epitaxy on undoped GaN buffer layers on (0001) sapphire substrates were investigated by thermal admittance spectroscopy, temperature dependence conductivity and thermally stimulated currents. A detailed trap characterization in the p-type GaN:Mg as well as in the undoped buffer layers shows that the TAS peaks observed from the p-type samples are caused by Mg-defects. Furthermore, the undoped buffer layer mainly dominates the optical induced deep defect-to-band transitions as measured by photoelectrical optical admittance spectroscopy. An increasing Mg-doping level introduces an enhancement of a deep defect signal at about EG-(280–360) meV. These results show the complex nature of the Mg defect and the introduction of further deep defects by the doping process.