A Surge Current Stable and Avalanche Rugged SiC Merged pn Schottky Diode Blocking 600V Especially Suited for PFC Applications

Abstract

Today silicon carbide (SiC) Schottky diodes are mainly used in the power factor control (PFC) unit of high end switched mode power supplies, due to their outstanding switching performance compared to Si pn diodes. In the case of the PFC it is required that the diodes are capable of handling surge currents up to several times the current of normal operation. The paper shows the surge current capability of a merged pn Schottky diode where the p-areas are optimized as efficient emitters. During normal operation the diode is behaving like a normal Schottky diode whereas during surge current condition the diode is behaving like a pn diode. For a sine half wave of 10 ms we achieved a non repetitive peak forward current capability of about 3700 A/cm2 which is about ten times rated current (for comparison: destructive current density of a standard Schottky diode ~ 1650 A/cm²). Additionally the device shows a stable avalanche and is able to withstand a single shot avalanche of 9.5 3s and 12.5 mJ.