The theoretical operating temperature of Silicon Carbide power semiconductors is much higher than that of traditional silicon power semiconductors. Due to mismatched packaging and integration technologies, there is a lack of research on the characteristics of unipolar Silicon Carbide power semiconductor over the wide temperature range, which hinders the development of power electronic technology towards high power density. In this paper, the bipolar characteristics of Silicon Carbide planar MOSFET and Schottky diodes as typical unipolar devices at extremely high temperatures are discovered and investigated, based on the static and dynamic characteristics over a wide temperature range (25 ℃ ~ 400 ℃) using the previously proposed advanced high-temperature silicon carbide power module. Through theoretical analysis and simulations, the mechanism of bipolar characteristics at extremely high temperatures was determined, and preliminary thermal runaway analysis are conducted. This work provides theoretical guidance for the future design of high-temperature power modules, chip manufacturing, and the development of high-power-density and high-temperature power electronic technology.