Electronic properties and deep traps in electron-irradiated n-GaN

The study is concerned with the effect of electron irradiation (with the energies E = 7 and 10 MeV and doses D = 1016−1018 cm−2) and subsequent heat treatments in the temperature range 100–1000°C on the electrical properties and the spectrum of deep traps of undoped (concentration of electrons n = 1 × 1014−1 × 1016 cm−3), moderately Si-doped (n = (1.2−2) × 1017 cm−3), and heavily Si-doped (n = (2−3.5) × 1018 cm−3) epitaxial n-GaN layers grown on Al2O3 substrates by metal-organic chemical vapor deposition. It is found that, on electron irradiation, the resistivity of n-GaN increases, this is due to a shift of the Fermi level to the limiting position close to E c −0.91 eV. The spectrum of deep traps is studied for the initial and electron-irradiated n-GaN. It is shown that the initial properties of the irradiated material are restored in the temperature range 100–1000°C, with the main stage of the annealing of radiation defects at about 400°C.