Electrically Active Defects in Neutron-Irradiated HPSI 4H-SiC X-Ray Detectors Investigated by ZB-TSC Technique

Electrically active defects in high-purity semi-insulating (HPSI) 4H-silicon carbide (4H-SiC) X-ray detectors have been characterized before and after neutron irradiation by zero-bias thermally stimulated current (ZB-TSC) and high-temperature resistivity measurements. The ZB-TSC measurements prior t...

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Veröffentlicht in:IEEE transactions on nuclear science 2017-08, Vol.64 (8), p.2377-2385
Hauptverfasser: Raja, P. Vigneshwara, Narasimha Murty, N. V. L.
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Sprache:eng
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Zusammenfassung:Electrically active defects in high-purity semi-insulating (HPSI) 4H-silicon carbide (4H-SiC) X-ray detectors have been characterized before and after neutron irradiation by zero-bias thermally stimulated current (ZB-TSC) and high-temperature resistivity measurements. The ZB-TSC measurements prior to irradiation reveal nine hole traps in the energy range of 0.22-1.16 eV and two electron traps at E c - 0.35 eV and E c - 0.44 eV. For the same case, high-temperature resistivity measurements yield thermal activation energy in the range of 1-1.3 eV. It is considered that the hole traps at E v +0.83 eV and E v +1.16 eV along with defects located near the activation energies are possibly responsible for the substrate compensation. A poor resolution of 11.8-keV full-width at half-maximum (at 40 keV of 152 Eu) with un-irradiated HPSI 4H-SiC detectors is attributed to the charge trapping and polarization effects. After neutron irradiation at the fluence of 10 11 n/cm 2 , seven new traps (E v + 0.68 eV, E v + 1.08 eV, E v + 1.22 eV, E c - 0.72 eV, E c - 0.9 eV, E c - 1.04 eV, and E c - 1.1 eV) are identified with no significant changes in the activation energies. This indicates that the substrate resistivity is unaffected by the neutron-irradiation-induced defects. No considerable changes in the X-ray spectral response are noted at 10 11 n/cm 2 .
ISSN:0018-9499
1558-1578
DOI:10.1109/TNS.2017.2720192