| 摘要 |
To provide a super high-speed heterojunction bipolar transistor, a semiconductor device including such a heterojunction bipolar transistor has a structure wherein a subcollector layer, collector layer, base layer, emitter layer (InGaP layer) and emitter cap layer are successively formed in predetermined shapes a surface of a semi-insulating GaAs substrate, an inner edge part of a base electrode overlaps a periphery of the emitter layer, and the base electrode is electrically connected to the base layer by an alloy layer formed by alloying the emitter layer under the base electrode. The emitter layer is selectively formed on the base layer. The base electrode extends from the peripheral part of the emitter layer across the base layer, and the alloy layer extends to a midway depth of the base layer. The edge of the base layer is situated further inside than the outer edge of the base electrode.
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