Different ion implanted edge terminations for Schottky diodes on SiC

In this paper, we report on the fabrication and electrical characterization of ion implanted guard rings for Schottky diodes on 4H SiC. For improving the performance of the devices, lowering the leakage current, and increasing the breakdown voltage, ion implanted guard rings seem to be the best choice. Two different methods, the resistive guard ring and the counter doped guard ring are investigated. Therefore, ion implantation of carbon and aluminum with different doses and annealing steps has been carried out. The implanted areas has been used as edge termination for Tungsten, Molybdenum, and Nickel Schottky diodes. The diodes has been electrical characterised at different temperatures. The influence of deep traps in the guard ring area on the electrical behavior is explained. The implantation dose varied from 1.2·10¹² cm^-2 to 1·10¹⁵ cm^-2. Different annealing processes were applied to minimize reverse leakage currents. The diodes showed a barrier height and a ideality factor of φ_B = 0.91 eV and n = 1.026 for Molybdenum and φ_B = 1.12 eV and n = 1.028 for Tungsten, respectively. The diodes showed a R_on in the range of 1.8 mΩcm² up to 2.4 mΩcm² at 1.5 V.