Method of manufacturing a field effect transistor with improved isolation between electrode

摘要

A field effect transistor has (a) a channel layer formed by a non-doped first semiconductor material (b) an electron supply layer formed by a doped second semiconductor material having an electron affinity which is lower than the affinity of the first semiconductor material, and (c) a contact layer formed by a doped third semiconductor material having an electron affinity which is higher than the affinity of the second semiconductor material. These layers are successively formed on a substrate of semi-insulating semiconductor material. Ions are implanted and a surface side portion of the contact layer is removed in a region other than at active portions in order to retain at least a part at a substrate side of the contact layer. By this arrangement, an excellent isolation can be achieved without producing large steps due to the mesa shape. Leakage current is not produced. There is no deterioration of the pinch off characteristic and withstand voltage. Noise characteristics and output efficiencies are excellent. There are no interruptions at electrode forming portions and the yield of fabrication is improved.