Effect of surface passivation on breakdown voltages of 4H-SiC Schottky barrier diodes

In this paper, the effect of surface passivation on the breakdown voltage of 4H-SiC Schottky barrier diode (SBD) was investigated. The SBDs having various passivation structures were fabricated. The passivation layers consist of 2 different ones: (1) thermal oxide with a post oxidation annealing, or no oxide by removing the oxide, and (2) plasma-enhanced chemical vapor deposited (PECVD) oxide, phosphosilicate glass (PSG), or polyimide (PI). The results show that the SBD having a sacrificial oxide as 1st passivation layer and a PI as 2nd passivation layer exhibited lower leakage current by a factor of more than 2 for the reverse bias above 1000 V than the others and its breakdown voltage (VBR) was 2254 V, which corresponds to 93% VBR of a parallel-plane ideal device.