| 摘要 |
PURPOSE: To evade element characteristics deterioration due to the band gap contraction effect of a heavily doped base layer, and obtain excellent characteristics, by constituting a first-a sixth semiconductor layers which are individually specified. CONSTITUTION: Semiconductor layers 2-4 are made a collector. A semiconductor layer 5 is made a base. Semiconductor layers 6, 7 are made an emitter. The semiconductor layer 5 has an electrically neutral region in the state of operation, which region contains second conductivity type charge carriers and impurities of 5×10<-18> cm<-3> or more which supply the charge carriers. The semiconductor layer 6 contains impurities which supply first conductivity type charge carriers to restrain the tunnel current of a PN junction which is formed between the semiconductor layers 5 and 6. The semiconductor layer 4 has the thickness and impurities for supplying first conductivity type charge carriers, in order that the first conductivity type charge carriers may be able to permeate a potential barrier by the tunneling effect which barrier is generated by the band gap contraction effect of the semiconductor layer 5 and obstructs the flow of the first conductivity type charge carriers to the semiconductor layer 4.
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