Simulation Study of a Novel Current-Limiting Device: A Vertical α-SiC JFET - Controlled Current Limiter

Abstract

Keyword : Current limiter, JFET, serial protection device, high voltage. Abstract : Considering fault current limiters for serial protection, a lot of structures exist, from regulation to other complex systems such as circuit breakers, mechanical switches or more conventional system : fuses. Up to now, only few semiconductor current limiter structures were described in papers [1]. Although Current Regulative Diode components exist [2, 3], the voltage and current capabilities (V BR =100 V, I max =10 mA), do not allow to use them in power systems. A comparison of a silicon Current Regulative Diode (CRD) and an equivalent SiC one demonstrates the thermal and electrical limitations of silicon. This paper deals with a novel bi-directional current limiter structure based on a vertical α-SiC VJFET, with both buried gate and source. This device was designed for short circuit protections. Simulations were performed with ISE-TCAD [4] to evaluate static and transient electrical characteristics of the VJFET, according to several specifications : voltage capability, current rating, time during which the device can sustain a short circuit. Simulations allow geometrical design and doping profile estimation as well as the technological process to realize such a component. Both 6H and 4H-SiC Controlled Current Limiter (CCL) have been realized. Electrical characterizations of fabricated devices underline the limiting effect and the command ability.