Modified Thermal Model Considering Peltier Effect and Thomson Effect for 4H-SiC GTO Thyristors

Silicon carbide (SiC) gate turn-off thyristors (GTOs), distinguished by their high current density, high blocking voltage, high switching frequency, and excellent thermal resistance, are highly suitable as pulse switches in pulsed power systems. However, their reliability remains a critical issue requiring urgent attention. Existing research on the thermal failure mechanisms of SiC GTOs is limited, partly due to the neglect of p–n junction voltage effects on thermal distribution. In this work, the Seebeck coefficient (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i>) in the thermodynamic model is modified, which considers for the first time the previously neglected Peltier and Thomson heats induced by the Seebeck effect in 4H-SiC GTOs. Simulation analysis reveals that the modified model captures localized heat concentration beneath the GTO anode with enhanced accuracy. The modified model predicts approximately 1 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> W/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sup> more heat generation within the 6-μm region beneath the anode. This result highlights the model’s ability to capture the Seebeck effect, which was omitted in the default TCAD model, providing a more accurate representation of the thermal behavior in 4H-SiC GTOs and other bipolar power devices.