Radiation Resistance of High-Voltage Silicon and 4H-SiC Power p-i-n Diodes

Abstract

The different effect of displacement damage produced by neutron irradiation on the static characteristics of 4.5-kV silicon and 4H silicon carbide (SiC) p-i-n power diodes is explained using deep level transient spectroscopy (DLTS), <inline-formula> <tex-math notation= LaTeX >${C}$ </tex-math></inline-formula>–<inline-formula> <tex-math notation= LaTeX >${V}$ </tex-math></inline-formula> profiling, and open-circuit voltage decay (OCVD) measurements. The number of introduced defects in SiC is higher, also the degradation of carrier lifetime and carrier removal proceeds more swiftly in SiC than those in silicon. However, smaller dimensions and a higher doping level of the n-base of the SiC diode compensate for these negative effects. As a result, the SiC p-i-n diode exhibits substantially higher resistance to neutron irradiation at higher fluences when the diode loses its ON-state carrier modulation capability. SiC also shows a negligible effect of irradiation on leakage current due to the wider bandgap. One may assume a better reliability of SiC bipolar devices over the silicon in a high neutron radiation environment.