| 摘要 |
PROBLEM TO BE SOLVED: To provide a heterojunction bipolar transistor having a base layer with a narrow bandgap. SOLUTION: Since Ge is used for the base layer 1, the bandgap in a room temperature can be as small as approximately 0.66 eV. Further, unlike GaInNAs and GaAsSb, which have been used in a conventional heterojunction bipolar transistor, the base layer is a single element crystal, so that composition control is not required and a crystal manufacturing process is easy. For example, when InGaP is used for an emitter layer 2, since selective etching is conducted by hydrochloric acid to expose the base layer 1, a device manufacturing process becomes easy. As a result, the provision of the heterojunction bipolar transistor having the base layer 1 with a narrow bandgap can be achieved. COPYRIGHT: (C)2003,JPO
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