| 摘要 |
PURPOSE:To enable the trapping of light generated in a well layer to be successfully performed by providing a resonance quantum well consisting of InAlAs/ InGaAs/InAlAs, and providing a base layer consisting if InAlGaAs whose Al composition is graded, said base layer being opposed to the emitter layer through the resonance quantum well. CONSTITUTION:There are provided a resonance quantum well 15 provided so as to be contacted with an emitter layer 16 and consisting of respective InA As/InGaAs/InAlAs layers, and a P<+> type InAlGaAs graded base layer 14 provided so as to be contacted with a InAlAs barrier layer 15A in the resonance quantum well, the Al composition of which is graded. With this, even if the barrier layer 15A of InAlAs in the resonance quantum well 15 is thinly formed to an extent which does not prevent the resonance tunneling of carriers, the InGaAs is maintained low as compared with the well layer because the refractive index of the graded base layer 14 which was formed so as to be contacted with the barrier layer is approximately same as that of InAlAs, whereby the light generating in the well layer can fully be trapped.
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