| 摘要 |
PURPOSE:To prevent a thin InGaAs base layer from being damaged in such a way that a dry etching method is applied at a selective etching process of the InGaAs layer and that a barrier layer is used as an etching stopper. CONSTITUTION:When an In(AlxGa1-x)As(0<x<=1) layer (e.g. a barrier layer 5 at the side of an AlGaAs emitter) and an InGaAs layer (e.g. an n<+> type InGaAs emitter layer 6), both being laminated in succession in order to create a heterojunction, are etched selectively, the InGaAs layer is first etched by means of a dry etching method (e.g. a reactive ion etching method using CCl2F2 as an etching gas), and this etching process is stopped as soon as it reaches the In(AlxGa1-x)As(0<x<=1) layer. Then, the In(AlxGa1-x)As (0<x<=1) layer is etched by means of a wet etching method. Through this constitution, it is possible to selectively expose the surface with high accuracy without causing damage to the InGaAs layer which is a substrate for a barrier layer. |
