High-Voltage Silicon Carbide Thyristors on N-Doped Epi for Pulsed Power

The Army Research Laboratory (ARL) has funded the development of high-voltage silicon carbide (SiC) thyristors and diodes for pulsed power switching, culminating in the novel 1.0 cm2, 15-kV SiC thyristor with n-type doping in the drift layer. N-type thyristors have been predicted to achieve faster switching speeds and lower switching losses, but were only recently realized following the development of novel fabrication techniques. These devices are targeted to reduce volume and increase reliability of pulsed switches in high-energy systems. ARL and Texas Tech University characterized the first fabrication lot of these devices for high-voltage DC-blocking capability (<1 μA leakage at 15 kV), optimal turn-on controls (4 A gate pulse), and on-state resistance at high current densities (up to 3 kA/cm2). This paper presents recent analysis of the turn-on speed and dI/dt capability for low-kHz pulse repetition of the n-type SiC thyristors as compared to previously reported 15-kV p-doped SiC thyristors. The current through the n-thyristor peaks 50 ns earlier, reaches 10% higher amplitude, and has significantly faster dI/dt as compared to the similarly designed p-thyristor.