Performance improvement of SiC n-LTT by semi-through via structure

Compared to Si thyristors, SiC thyristors exhibit superior performance. As an essential category of SiC thyristors, SiC Light-Triggered Thyristors (LTTs) with a blocking voltage of 15 kV or below typically employ a p-type long-base structure. In this work, n-type long-base SiC LTTs were simulated and analyzed, revealing that p-type substrate SiC n-LTT exhibits high conduction resistance, while n-type substrate SiC n-LTT encounters difficulties in turning on. To address these issues, this work proposes a semi-through via structure for n-type long-base SiC LTTs to reduce conduction resistance, with numerical simulations conducted using TCAD software. The proposed structure effectively mitigates the high conduction resistance in p-type substrate SiC n-LTT and resolves the turn-on difficulty in n-type substrate SiC n-LTT, with a detailed analysis of these challenges. Simulation results indicate that the n-type substrate SiC n-LTT with a semi-through via structure can be successfully turned on. At an anode current density of 100 A/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, it exhibits a forward conduction voltage drop of 4.0 V, which is lower than the 4.2 V observed in the p-type substrate SiC n-LTT. In addition, its on-state resistance is lower than that of the p-type long-base SiC LTT, thereby significantly improving the device’s overall conduction performance.