Ionization Damage Effects of Pulse Discharge Circuit Switched by Anode-Short MOS-Controlled Thyristor

Abstract

The MOS-controlled Thyristor (MCT) has been characterized by MOS-gating, high current rise rate, and high blocking capabilities. The anode short MCT (AS-MCT) is distinguished from the conventional MCT by an anode-short structure, which forms an extracting path for the leakage current at the gate-ground and develops a normally-off characteristic. The AS-MCTs are ideal switches for pulse discharge application. As a composite structure made of metal-oxide-silicon and bipolar junction transistors, AS-MCT is susceptible to ionization damage. This work reports the experimental results for the degradation of zero-load (or short) pulse discharge circuit characteristics induced by the ionization damage of its AS-MCT switch following cobalt- $60~\gamma $ -ray dose up to 9160 Gy(SiO2). The radiation-induced leakage current in AS-MCT accounts for the degradations of charging time and peak surging current of the pulse discharge circuit. These degradations show a “tick”-like dependence on the $\gamma $ -ray dose which are recoverable after high dose exposures, thousands of Gy(SiO2). From device and circuit physics perspectives, the damages on pulse discharge circuit are modelled, and then, this article proposes, the mechanism behind the characteristics degradation of pulse discharge circuit from the total ionization dose damage of AS-MCT switch.

Keywords

• Total ionization dose damage
• anode-short MOS-controlled thyristor
• pulse discharge circuit
• surge current