Thermal neutron irradiation effects on structural and electrical properties of n-type 4H-SiC

In this article, the thermal neutron irradiation (NI) effects on the structural properties of n-4H-SiC and electrical properties of Al/n-4H-SiC Schottky contacts have been reported. The noticeable modifications observed in the irradiated samples were studied by using different techniques. The X-ray diffraction studies revealed a decrease in the lattice parameter of the irradiated samples due to isotopic modifications and irradiation-induced defects in the material. As a result, the energy bandgap, Urbach energy, longitudinal optical phonon-plasmon coupling mode, free carrier concentration, defect related photoluminescence and nitrogen bound exciton photoluminescence bands were prominently affected in the irradiated samples. The current-voltage characteristics of neutron irradiated Al/n-4H-SiC Schottky contacts were also strikingly affected in terms of zero-bias offset as well as decrease in the forward current. These modifications along with the increase in the Schottky junction parameters (such as ideality factor, Schottky barrier height and series resistance) were attributed to neutron-induced isotopic effects and decrease in the free carrier concentration due to induced defect states.