| 摘要 |
PROBLEM TO BE SOLVED: To provide a hetero junction bipolar transistor, which has a base layer of GaAsSb, and can realize a high current gain cut-off frequency (fT). SOLUTION: The hetero junction bipolar transistor comprises a collector layer 3 of at least InP, a base layer 4 of p-type GaAsSb, and an n-type layer of group III-V compound semiconductor having a larger band gap than that of the base layer 4, stacked in this order on a semiconductor substrate 1, where the collector layer 3 comprises an undoped InP layer 3c, p-type InP layer, and n-type InP layer, stacked in this order from the base layer 4.
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