Abstract:
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$^\circ$C on the electrical properties and the spectrum of deep traps of undoped (concentration of electrons $n$ = 1 $\times$ 10$^{14}$–1 $\times$ 10$^{16}$ cm$^{-3}$), moderately Si-doped ($n$ = (1.2–2) $\times$ 10$^{17}$ cm$^{-3}$), and heavily Si-doped ($n$ = (2–3.5) $\times$ 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$^\circ$C, with the main stage of the annealing of radiation defects at about 400$^\circ$C.
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