| 摘要 |
PROBLEM TO BE SOLVED: To achieve enhancement of operational reliability of an HBT and high speed operation simultaneously. SOLUTION: In the HBT, a collector contact layer 12, a collector layer 13, a base layer 14, emitter layers 15 and 16, an emitter contact layer 17, and emitter electrodes 18 and 19 are formed on a semi-insulating substrate 11; and a base electrode 21 and a collector electrode 25 are fixed onto the base layer and the collector contact layer. The emitter layer is formed of a first emitter layer 15 on the base layer side, and a second emitter layer 16 on the emitter contact layer side. A depleted ridge is formed on the extension 23 of the first emitter layer. Furthermore, the second emitter layer, the emitter contact layer, and the emitter electrode form an emitter mesa 22 having an undercut 31 for the emitter electrode and the base electrode is formed to be self-aligned with the emitter mesa. COPYRIGHT: (C)2008,JPO&INPIT
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