PURPOSE: To obtain a bipolar transistor using SiC, which excels in its thermal resistance, by constituting it through using an α-type SiC layer of unilateral conductivity type as its emitter region, polycrystalline silicon carbide layers of the other conductivity type as its base region, and polycrystalline silicon carbide layers of the unilateral conductivity type as its collector region.

CONSTITUTION: A heterojunction bipolar transistor comprises an α-type SiC layer 2 of one conductivity type, polycrystalline silicon carbide layers 3 of the other conductivity type, which are laminated on the α-type SiC layer 2 of the unilateral conductivity type, and many independent polycrystalline silicon carbide layers 4 of the unilateral conductivity type, which are laminated on the polycrystalline silicon carbide layers 3 of the other conductive type. The heterojunction bipolar transistor is constituted using the α-type SiC 2 of the unilateral conductivity type as its emitter region, the polycrystalline silicon carbide layers 3 of the other conductivity type as its base region, and the polycrystalline silicon carbide layers 4 of the unilateral conductivity type as its collector region. Thereby, this bipolar transistor can be used in the place of high temperature, where no conventional device made of silicon and gallium arsenide can be used, as a bipolar transistor which keeps the high-speed quality caused by its heterojunction and excels in its thermal resistance.