A selectivity study of the etching of lattice‐matched , , and in solutions is reported. Selectivities as high as 500 and 187 are obtained for the etching of on and on , respectively. The selectivity for the etching of on varies from 25 at a solution ratio of 1 to a selectivity of 2.5 at a solution ratio of 10. The activation energies and the etch profiles of and are also reported. The implications of this selectivity variation for the fabrication of heterostructure field‐effect transistors are discussed.