| 摘要 |
PURPOSE:To form a recess with accuracy, by forming on a contact layer a mask and contact layer containing aluminium which is distributed therein such that the concentration of aluminium is lower toward the contact layer and higher toward the surface, and then forming the recess by means of etching. CONSTITUTION:A GaAS active layer 2 and an N<+> type GaAs contact layer 3 are formed on a semi-insulating GaAs substrate 1. An N<+> type AlGaAs layer 5 is formed thereon for serving both as mask and contact layers such that a concentration of aluminium it contains becomes lower toward the the layer 3 and higher toward the surface. A photoresist film provided so as to form an aperture 6a. Subsequently, the layers 5, 3 and 2 are partially etched to form a recess 7. By this etching, the layer 5 is provided with a tapered aperture 5A which is enlarged toward the layer 3, and therefore the recess 7 following this aperture is formed to have a pattern corresponding to the enlarged pattern of the aperture. Subsequently, the film 6 is removed and a source electrode 8S, a drain electrode 8D and a gate electrode 8G are provided. |
