| 摘要 |
PROBLEM TO BE SOLVED: To provide a wafer for semiconductor devices wherein the life of a heterobipolar transistor can be improved by blocking defects appearing in a collector contact layer fromn propagating to upper layers than this layer. SOLUTION: As for a wafer for semiconductor devices which has an n-type conductivity collector contact layer 2, an n-type conductivity collector layer 3, a p-type conductivity GaAs crystal or InGaAs crystal or AlGaAs crystal base layer 4, an n-type conductivity AlGaAs crystal or InGaP crystal emitter layer 5 forming a heterojunction with the base layer 4, and an n-type conductivity emitter contact layer 6 on a GaAs substrate 1; an In planar doped layer 10 is formed between the collector contact layer 2 and the collector layer 3.
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