| 摘要 |
PROBLEM TO BE SOLVED: To provide a heterojunction bipolar transistor which has base sheet resistance equivalent to InGaAs base DBHT and exhibits ideal characteristic equivalent to GaAsSb base DHBT. SOLUTION: The transistor contains a semiconductor layer which has an n-type as a first conductivity type, in an interface between a base layer and a collector layer. In a heterointerface with the collector layer of the semiconductor layer, energy in a valence band is higher than energy in a valence band of the collector layer, and energy in a conduction band is higher than energy in a conduction band of the collector layer. In a heterointerface with the base layer, energy in a valence band is higher than energy in a valence band of the base layer, and energy in a conduction band is higher than energy in a conduction band of the base layer. The amount of energy discontinuity in a conduction band in the heterointerface with the collector layer is larger than the difference of an energy gap the heterointerfaces with the collector layer and the base layer.
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