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 ηFP(Ga) is approximately 560 cm–1, while in the nitrogen sublattice, ηFP(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 ηFP(Ga) is approximately 4.7 cm–1, while in the nitrogen sublattice, ηFP(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.