Effect of Radiation-Induced Defects in Gallium and Nitrogen Lattices on n-GaN Conductivity Compensation

A comparative analysis of radiation-induced defect formation in the gallium and nitrogen sublattices of gallium nitride is conducted under irradiation by 15-MeV protons and 0.9-MeV electrons. Numerical modeling using the SRIM software is performed for proton deceleration, while analytical calculations are applied for electrons. The analysis shows that, under proton irradiation, the total vacancy-generation rate in the gallium sublattice η_FP(Ga) is approximately 560 cm^–1, while in the nitrogen sublattice, η_FP(N) is approximately 1340 cm^–1. Detailed numerical calculations using the Full Cascade mode indicate that the vacancy-formation rate due to protons in the gallium sublattice is 110 cm^–1, with an additional 450 cm^–1 generated by cascade processes. In the nitrogen sublattice, this disparity is even more pronounced, with 60 cm^–1 attributed to direct proton interaction and 1280 cm^–1 to cascade processes. Under electron irradiation, the vacancy-generation rate in the gallium sublattice η_FP(Ga) is approximately 4.7 cm^–1, while in the nitrogen sublattice, η_FP(N) is approximately 2.0 cm^–1. For the experimental study of radiation-induced defects in n-GaN, which create deep levels and compensate for the material’s conductivity, the forward current–voltage characteristics of Schottky diodes based on n-GaN are recorded. The analysis demonstrates that the charge-carrier removal rates in n-GaN are 0.47 cm^–1 under electron irradiation and 150 cm^–1 under proton irradiation. A comparison of the calculated and experimental parameters of radiation-induced defect formation provides insights into the compensation mechanism and the radiation-induced defects responsible for this process.