| 摘要 |
PURPOSE:To improve the rapidity of a hetero junction bipolar transistor by forming an in layer between a GaAs layer and an InAs layer, and heat treating it in an As atmosphere to form a very preferable grading layer, thereby remarkably reducing a contact resistance. CONSTITUTION:A grading layer of an extremely thin In layer 107 is formed on an AlGaAs/GaAs layer 105 which constitutes an emitter layer, the layer is heated in an As atmosphere, an InGaAs layer 108 in which the molar ratio of InAs or In exceeds 0.5 is grown, and an ohmic contact is formed of a Ti/Au thin film on the layer 108. Thus, since its contact resistance is remarkably reduced, its rapidity can be enhanced.
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