Performance degradation and defect characterization of Ni/4H-SiC Schottky diode neutron detector in high fluence rate neutron irradiation

Abstract

A long-standing objective in neutron detection is to develop high-quality detectors with good radiation resistance; silicon carbide (SiC) detectors are considered to be good options. Although SiC neutron detectors have been successfully developed, the performance of SiC detectors leave much to be desired: performance degradation is inevitable in neutron irradiation and becomes serious above the neutron fluence of 1014 n/cm2 (Dulloo et al., 1999, 1997; Wu et al., 2014; Nava et al., 2006; Sze and Ng, n.d.; Liu et al., 2017). The defects induced in the depletion region of SiC detector were generally considered to be responsible for it, but after analyzing performance degradation and characterizing radiation defects of Ni/4H-SiC Schottky diode detectors, which were irradiated in Xi'an pulsed reactor with a fluence rate of 2.05 × 1013 n/cm2 s and a total radiation fluence of 2.1 × 1016 n/cm2 (mixture of thermal and fast neutrons), it is found that interface performance degradation of nickel electrode and SiC epitaxial layer induced by neutron irradiation can also influence its performance. Thus the design of SiC neutron detectors should not only pay attention to the quality of the detector's sensitive layer (SiC epitaxial layer) but also consider radiation effects on the interface between electrode and SiC epitaxial layer, which has significant importance for improving performance of SiC neutron detectors and extend their application to intense radiation fields.