HEMT with etch-stop

摘要

A compound semiconductor device comprises an enhancement-mode transistor and a depletion-mode transistor, each of which has a heterojunction and utilizes a two-dimensional electron gas. The method of producing the device comprises the steps of: forming an undoped GaAs channel layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs electron-supply layer so as to form the heterojunction; forming an N-type GaAs layer; forming an AlGaAs layer; selectively etching the AlGaAs layer to form a recess; performing an etching treatment using an etchant which can etch rapidly GaAs and etch slowly AlGaAs to form simultaneously grooves for gate electrodes of the enhancement-mode transistor and the depletion-mode transistor, the bottoms of the grooves being in the N-type AlGaAs layer and the distance between the bottoms being equal to the thickness of the AlGaAs layer; and forming simultaneously the gate electrodes in the grooves.