High-Voltage 4H-SiC Schottky Diodes with Field-Plate Edge Termination

High-voltage (2000V) 4H-SiC Schottky diodes are fabricated. To suppress the premature breakdown at the edge of diode structures, a field plate is formed as the edge termination. In this plate, an insulator layer is formed via the self-aligned implantation of high-energy (53 MeV) argon ions into 4H-SiC. To mask the active region of the diodes, 10–12-μm-thick nickel columns with vertical walls are grown on Schottky contacts by local electrochemical deposition. A comparison of the current–voltage characteristics of terminated and nonterminated diodes shows that the forward current–voltage characteristics barely degrade after implantation, whereas the reverse current–voltage characteristics are greatly improved. Both the forward and reverse current–voltage characteristics of terminated diodes are well described in terms of the classical thermionic emission model if lowering of the Schottky-barrier height with increasing bending of energy bands is taken into account.