Compound semiconductor device having an emitter contact structure including an InxGa1-xAs graded-composition layer

摘要

A compound semiconductor device wherein a contact to an n type AlxGa1-xAs layer comprises an InxGa1-xAs graded-composition layer, an InxGa1-xAs contact layer having a constant composition and a metal electrode layer, the InxGa1-xAs graded-composition layer is doped with an n type impurity which concentration is higher than a concentration of an impurity activated as n type, whereby, even when a thickness of the InxGa1-xAs graded-composition layer is made sufficiently small, a reduction in the carrier concentration of the thin graded-composition layer causes no increase of its resistance and a low-resistance contact is realized.