| 摘要 |
PROBLEM TO BE SOLVED: To provide a heterojunction bipolar transistor where the reliability is improved by preventing such a problem that beryllium atoms diffuse from a base to an emitter, and its formation method. SOLUTION: A heterojunction bipolar transistor is doped with phosphor (24) within its sub collector layer (20). The existence of phosphor couples any interlattice gallium with phosphor (24) and shifts the gallium to other lattice section. As a result, the interlattice gallium ceases to diffuse to the base layer, consequently the gallium arranges the beryllium to cease to be replaced and diffused. In place of the doping with phosphor, a layer including phosphor can be used.
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