IN x?Ga 1-x?P STOP-ETCH LAYER FOR SELECTIVE RECESS OF GALLIUM ARSENIDE-BASED EPTITAXIAL FIELD EFFECT TRANSISTORS AND PROCESS THEREFOR

摘要

The present invention is drawn to an InxGa1-xP etch-stop layer for improving the uniformity of devices across an epitaxial wafer incorporating a high-low-high MESFET structure. The range of permissable values of x will vary as a function of the thickness of the etch-stop layer. To this end, preferably x is on the order of 0.5 in order to maintain lattice match with the GaAs substrate. Also, a novel process for selective recess etching of GaAs field-effect transistors is disclosed. The present invention envisions the use of a relatively thin (10-30 Angstrom) layer of the InxGa1-xP material to effect the selective recess etching of the material to a point where a relatively uniform thickness of n material remaining above the channel layer is realized.