Fast neutron irradiation effects in n-GaN

Abstract

Impact of deep levels on the electrical conductivity and luminescence of gallium nitride codoped with carbon and silicon J. Appl. Phys. 98, 053704 (2005); 10.1063/1.2005379 A method to determine deep level profiles in highly compensated, wide band gap semiconductors J. Appl. Phys. 97, 083529 (2005); 10.1063/1.1862321 Neutron irradiation effect on radio-frequency magnetron-sputtered GaN thin films and Au/GaN Schottky diodes The electrical properties and deep level spectra in undoped n-GaN films irradiated by fast neutrons are reported. The electron removal rate was ϳ5 cm −1 , and the dominant deep states introduced by neutron damage were electron traps with activation energy of 0.75 eV. For high doses of 1.7ϫ 10 17 -10 18 cm −2 the material becomes semi-insulating n-type with the Fermi level pinned near E c − 0.85 eV. Deep level spectra are dominated by electron traps with activation energy of 0.75 eV, close to the energy of the Fermi level pinning in heavily irradiated material. Neutron irradiation also introduces a high density of centers giving rise to strong persistent photocapacitance. The observed phenomena are explained under the assumption that the dominant defects in neutron irradiated GaN are disordered regions produced by high-energy recoil atoms.

Review of using gallium nitride for ionizing radiation detection

“…Due to these induced defects, trapping centers are created, and the Fermi level is pinned within the energy levels of these defects. For example, Polyakov et al 117 found that under a high neutron fluence of $10…”

Radiation Damage in GaN‐Based Materials and Devices

“…With rare exceptions, only for higher electron energies [11], heavier ions (He, N) [15,19], neutron irradiation [20] or higher density of defects in proton implanted samples (as for 150 keV protons with the dose over 5×10 14 cm -2 [21]) are deeper traps commonly detected. Electron traps that are generally observed in these cases show the activation energies of 0.75-0.8 eV, 0.95-1.2 eV [11,15,[19][20][21]. The 0.8 eV traps show decrease of the ionization energy with increasing electric fi eld whereas the 1 eV traps energy does not vary with electric fi eld.…”

“…The fi rst type of behavior is expected for donors because of the PooleFrenkel effect [22], whilst the second type of behavior is characteristic of acceptors that are neutral when they emit an electron [22]. The attribution based mostly on theoretical calculations tends to ascribe the fi rst to Ga i 2+ deep donors and the second to N i 2+ deep acceptors [9,11,15,20]. In addition to these deep centers, implantation of n-GaN with 150 keV protons to doses higher than 5×10 14 cm -2 creates deep electron traps whose energies increased from 0.2 eV at low dose to 0.25 eV, 0.32 eV and 0.45 eV at higher dose suggesting that these centers could be larger complexes produced by addition of new radiation defects to the more simple radiation defects formed at low doses [21].…”

“…In GaN it is located between the levels of N i acceptors and of Ga i donors. Moreover, lattice parameter measurements in heavily neutron irradiated GaN show a measurable increase indicating that the dominant defects could be interstitials [20,35,42]. Rutherford backscattering experiments on neutron irradiated GaN also point to a very high density of interstitials, predominantly Ga i [45].…”

Investigation of gate pulse induced interface trap behaviours and its relationship with threshold voltage instability in Algan/Gan-On-Si MIS-Hemts

“…The main degradation mechanisms such as the current collapse, the permanent increased leakage current, and the instable threshold voltage, are considered to associate with the trapping effect for AlGaN/GaN MIS-HEMTs [2][3][4][5][6]. Deep level Transient Spectroscopy (DLTS) is used to analyse the deep level defects in AlGaN/GaN MIS-HEMTs [7][8][9][10]. However, for a DLTS test, a well-controlled temperature cabinet with a wide temperature scope (dozens of K to hundreds of K) is required.…”