Effect of Proton and Electron Irradiation on Current-Voltage Characteristics of Rectifying Diodes Based on 4H-SiC Structures with Schottky Barrier

摘要

Forward and reverse current-voltage (I-V) characteristics of commercial rectifying Schottky diodes (SDs) based on silicon carbide (4H-SiC, base layer doping level 3×10~(15) cm~(-3)) have been studied under irradiation with 0.9 MeV electrons and 15 MeV protons. The starting diodes were characterized by a barrier height of about 1.5 eV and nearly ideal forward and reverse I-V characteristics. It was found that, at doses exceeding the threshold dose D_th, the series differential resistance R_s of the diodes grows as R_s ~ D~m (m = 10-15) and shows no tendency toward saturation. D_(th)=7×10~(15) cm~(-2) under electron irradiation, and D_th=4×10~(13) cm~(-2) in the case of irradiation with protons. Heating to 200°C results in that R_s decreases with activation energy of about 1.1 eV and R_s is partly annealed-out with activation energy of ~0.7 eV. The barrier height of the starting SDs changes only slightly under irradiation, but, possibly, the irradiation leads to an over-compensation of the n-type layer and formation of an additional barriers in the form of a pn junction.