Edge terminations for SiC high voltage Schottky rectifiers

A study of floating metal field rings (FMRs) and resistive Schottky barrier field plate (RESP) edge terminations for high-voltage silicon carbide (SiC) Schottky barrier diodes (SBD) is reported. For a drift region doping of 2×10¹⁶ cm^-3, numerical simulations indicated a breakdown voltage for an unterminated diode of about 225 V as compared to ≈1125 V for a parallel plane structure. For the FMR termination, simulations indicate a breakdown voltage of ≈600 V for a three-ring termination with a ring spacing of 0.8 μm. Experimentally determined breakdown voltages of SiC SBDs fabricated using FMR termination were >400 V as compared to ≈220 V for unterminated diodes. For the RESP termination, an analytical model was developed to study the effect of various design parameters, such as RESP length and sheet-resistance, on the breakdown voltage. This model was used to optimize various design parameters for SBDs fabricated using RESP termination