A selectivity study of the etching of lattice matched (LM) InCaAs/InAlAs on InP and metamorphic (MM) InGaAs/InAlAs on GaAs in succinic acid : hydrogen peroxide solutions is reported. Selectivities as high as 70 and 1030 are? respectively, obtained for the LM and MM InGaAs on InAlAs. Observations and measurements with an atomic force microscope of narrow recess and under-resist etch on LM InP materials are also presented. The ability of these solutions for fabrication of InGaAs/InAlAs heterojunction field effect transistors is discussed.