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 = 10 16 −10 18 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 × 10 14 −1 × 10 16 cm −3 ), moderately Si-doped ( n = (1.2−2) × 10 17 cm −3 ), and heavily Si-doped ( n = (2−3.5) × 10 18 cm −3 ) epitaxial n -GaN layers grown on Al 2 O 3 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.