Analysis of the forward I–V characteristics of Al-implanted 4H-SiC p-i-n diodes with modeling of recombination and trapping effects due to intrinsic and doping-induced defect states

In this paper the impact of silicon carbide intrinsic defect states, such as Z1/2 and EH6/7 centers, on the forward current-voltage curves of aluminum (Al) implanted 4H-SiC p-i-n diodes is investigated by means of a physics based device simulator. During the simulations, an explicit carrier trap effect due to an electrically active defect concentration produced by the Al+ ion implantation process in the anode region was also taken into account. The obtained current-voltage characteristics are compared with those measured experimentally for several samples at different current levels. It is found that intrinsic defect densities as high as the epilayer doping may lead to undesirable device properties and instability of the forward bias behavior. The diode ideality factor and the series resistance increase with the increase of defects and could be controlled by using high-purity epi wafers. Furthermore, due to their location in the bandgap and capture cross sections, the impact of Z1/2 centers on the device electrical characteristics is more severe than that of EH6/7 centers.