| 摘要 |
PROBLEM TO BE SOLVED: To reduce variation range of current amplification factor accompanying aging change by raising current amplification factor through the formation of a semiconductor layer comprising an n-AlGaAs emitter layer doped with Si and Se on a substrate. SOLUTION: An n+-GaAs sub-collector layer 2 is formed on a semi-insulating substrate 1 and an n-GaAs collector layer 3 is formed thereon, and the layers 2, 3 are doped with Si which is an n-type impurity. Then, a P+-GaAs based layer 4 is formed thereon and doped with C which is a p-type impurity. Thereafter, an emitter layer 6 by n-AlGaAs having n-AlGaAs graded layers 5, 7 in upper and lower part each is deposited. Compound doping is performed for it together with each of the graded layers 5, 7 by using both Si and Se, n-type impurities.
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