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 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
.