| 摘要 |
PURPOSE:To reduce a base current and to improve the current amplification factor of a hetero junction bipolar transistor by forming a section brought into contact with the intrinsic base region of an external base region of a semiconductor material having a wide band gap. CONSTITUTION:At least three layers of a first conductivity type first semiconductor layer 503 to become a collector, a second conductivity type second semiconductor layer 504 to become a base and a first conductivity type third semiconductor layer 506 to become an emitter are laminated on a substrate 501. Then, at least partial forbidden band width of the layer 506 constitutes a hetero junction bipolar transistor larger than that of the layer 504. Further, a base electrode 511 brought into contact with the second conductivity type external base region 504 disposed outside an intrinsic transistor region is provided. A second conductivity type semiconductor region 510 having a wider band gap than that of the intrinsic base region is disposed between the intrinsic base region and the external base region. Thus, the hetero junction bipolar transistor having high current amplification factor can be formed.
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