High-power 4H-SiC JBS rectifiers

This paper reports the detailed design, fabrication, and characterization of two sets of high-power 4H-silicon carbide (4H-SiC) junction barrier Schottky (JBS) diodes - one with a 1500-V, 4-A capability and another with 1410-V, 20-A capability. Two-dimensional (2-D) device simulations show that a grid spacing of 4 μm results in the most optimum trade-off between the on-state and off-state characteristics for these device ratings. JBS diodes with linear and honeycombed p⁺ grids, Schottky diodes and implanted p-i-n diodes fabricated alongside show that while 4H-SiC JBS diodes behave similar to,Schottky diodes in the on-state and switching characteristics, they show reverse characteristics similar to p-i-n diodes. Measurements on 4H-SiC JBS diodes indicate that the reverse-recovery time (τ_rr) and associated losses are near-zero even at a high reverse dI/dt of 75 A/μs. A dc/dc converter efficiency improvement of 3-6% was obtained over the fastest, lower blocking voltage silicon (Si) diode when operated in the 100-200 kHz range.