Electrical characterization of 4H-SiC Schottky diodes with RuWO_x Schottky contacts before and after irradiation by fast electrons

摘要

The impact of radiation damage on the device Performance of 4H-SiC Schottky barrier diodes (SBDs) with RuWO_x Schottky contacts, which were irradiated at room temperature with 9MeV electrons (absorbed dose of 50 Gy), is studied by current-voltage (Ⅰ-Ⅴ) and capacitance-voltage (C-V) methods measured in the temperature ränge of 85-400 K. We have observed the radiation-induced decrease of the Schottky barrier height (SBH) from original Φ_b= 1.13-1.06eV, increase of the ideality factor from « = 1.14 to 1.39 and the noticeable increase of the Saturation current from I_s = 7.29 to 77.31 pA and the series resistance from R_s = 2.9 to 7.9 Ωcalculated from I-V measurements at T= 300 K. As a result of electron irradiation deep energy levels originated in the structure and caused the increase of serial resistance and leakage current. The DLTS results have shown several deep energy levels, e.g., E_c - 0.637 eV pointing to radiation-induced Z_(1/2) structural defects in SiC. No degradation is observed froin the measured C-V curves. The experimental vatoe of the effective Richardson constant A~* = 50.68 A/cm~2/K~2 for the irradiated sample was calculated from the modüied Richardson plot.